text: /**
  * matter-js 0.9.0 by @liabru 2016-01-16
  * http://brm.io/matter-js/
  * License MIT
  */
  
  /**
   * The MIT License (MIT)
   * 
   * Copyright (c) 2014 Liam Brummitt
   * 
   * Permission is hereby granted, free of charge, to any person obtaining a copy
   * of this software and associated documentation files (the "Software"), to deal
   * in the Software without restriction, including without limitation the rights
   * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   * copies of the Software, and to permit persons to whom the Software is
   * furnished to do so, subject to the following conditions:
   * 
   * The above copyright notice and this permission notice shall be included in
   * all copies or substantial portions of the Software.
   * 
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
   * THE SOFTWARE.
   */
  
  (function(f){if(typeof exports==="object"&&typeof module!=="undefined"){module.exports=f()}else if(typeof define==="function"&&define.amd){define([],f)}else{var g;if(typeof window!=="undefined"){g=window}else if(typeof global!=="undefined"){g=global}else if(typeof self!=="undefined"){g=self}else{g=this}g.Matter = f()}})(function(){var define,module,exports;return (function e(t,n,r){function s(o,u){if(!n[o]){if(!t[o]){var a=typeof require=="function"&&require;if(!u&&a)return a(o,!0);if(i)return i(o,!0);var f=new Error("Cannot find module '"+o+"'");throw f.code="MODULE_NOT_FOUND",f}var l=n[o]={exports:{}};t[o][0].call(l.exports,function(e){var n=t[o][1][e];return s(n?n:e)},l,l.exports,e,t,n,r)}return n[o].exports}var i=typeof require=="function"&&require;for(var o=0;o<r.length;o++)s(r[o]);return s})({1:[function(require,module,exports){
  /**
  * The `Matter.Body` module contains methods for creating and manipulating body models.
  * A `Matter.Body` is a rigid body that can be simulated by a `Matter.Engine`.
  * Factories for commonly used body configurations (such as rectangles, circles and other polygons) can be found in the module `Matter.Bodies`.
  *
  * See the included usage [examples](https://github.com/liabru/matter-js/tree/master/examples).
  
  * @class Body
  */
  
  var Body = {};
  
  module.exports = Body;
  
  var Vertices = require('../geometry/Vertices');
  var Vector = require('../geometry/Vector');
  var Sleeping = require('../core/Sleeping');
  var Render = require('../render/Render');
  var Common = require('../core/Common');
  var Bounds = require('../geometry/Bounds');
  var Axes = require('../geometry/Axes');
  
  (function() {
  
      Body._inertiaScale = 4;
      Body._nextCollidingGroupId = 1;
      Body._nextNonCollidingGroupId = -1;
      Body._nextCategory = 0x0001;
  
      /**
       * Creates a new rigid body model. The options parameter is an object that specifies any properties you wish to override the defaults.
       * All properties have default values, and many are pre-calculated automatically based on other properties.
       * See the properties section below for detailed information on what you can pass via the `options` object.
       * @method create
       * @param {} options
       * @return {body} body
       */
      Body.create = function(options) {
          var defaults = {
              id: Common.nextId(),
              type: 'body',
              label: 'Body',
              parts: [],
              angle: 0,
              vertices: Vertices.fromPath('L 0 0 L 40 0 L 40 40 L 0 40'),
              position: { x: 0, y: 0 },
              force: { x: 0, y: 0 },
              torque: 0,
              positionImpulse: { x: 0, y: 0 },
              constraintImpulse: { x: 0, y: 0, angle: 0 },
              totalContacts: 0,
              speed: 0,
              angularSpeed: 0,
              velocity: { x: 0, y: 0 },
              angularVelocity: 0,
              isStatic: false,
              isSleeping: false,
              motion: 0,
              sleepThreshold: 60,
              density: 0.001,
              restitution: 0,
              friction: 0.1,
              frictionStatic: 0.5,
              frictionAir: 0.01,
              collisionFilter: {
                  category: 0x0001,
                  mask: 0xFFFFFFFF,
                  group: 0
              },
              slop: 0.05,
              timeScale: 1,
              render: {
                  visible: true,
                  sprite: {
                      xScale: 1,
                      yScale: 1,
                      xOffset: 0,
                      yOffset: 0
                  },
                  lineWidth: 1.5
              }
          };
  
          var body = Common.extend(defaults, options);
  
          _initProperties(body, options);
  
          return body;
      };
  
      /**
       * Returns the next unique group index for which bodies will collide.
       * If `isNonColliding` is `true`, returns the next unique group index for which bodies will _not_ collide.
       * See `body.collisionFilter` for more information.
       * @method nextGroup
       * @param {bool} [isNonColliding=false]
       * @return {Number} Unique group index
       */
      Body.nextGroup = function(isNonColliding) {
          if (isNonColliding)
              return Body._nextNonCollidingGroupId--;
  
          return Body._nextCollidingGroupId++;
      };
  
      /**
       * Returns the next unique category bitfield (starting after the initial default category `0x0001`).
       * There are 32 available. See `body.collisionFilter` for more information.
       * @method nextCategory
       * @return {Number} Unique category bitfield
       */
      Body.nextCategory = function() {
          Body._nextCategory = Body._nextCategory << 1;
          return Body._nextCategory;
      };
  
      /**
       * Initialises body properties.
       * @method _initProperties
       * @private
       * @param {body} body
       * @param {} options
       */
      var _initProperties = function(body, options) {
          // init required properties (order is important)
          Body.set(body, {
              bounds: body.bounds || Bounds.create(body.vertices),
              positionPrev: body.positionPrev || Vector.clone(body.position),
              anglePrev: body.anglePrev || body.angle,
              vertices: body.vertices,
              parts: body.parts || [body],
              isStatic: body.isStatic,
              isSleeping: body.isSleeping,
              parent: body.parent || body
          });
  
          Vertices.rotate(body.vertices, body.angle, body.position);
          Axes.rotate(body.axes, body.angle);
          Bounds.update(body.bounds, body.vertices, body.velocity);
  
          // allow options to override the automatically calculated properties
          Body.set(body, {
              axes: options.axes || body.axes,
              area: options.area || body.area,
              mass: options.mass || body.mass,
              inertia: options.inertia || body.inertia
          });
  
          // render properties
          var defaultFillStyle = (body.isStatic ? '#eeeeee' : Common.choose(['#556270', '#4ECDC4', '#C7F464', '#FF6B6B', '#C44D58'])),
              defaultStrokeStyle = Common.shadeColor(defaultFillStyle, -20);
          body.render.fillStyle = body.render.fillStyle || defaultFillStyle;
          body.render.strokeStyle = body.render.strokeStyle || defaultStrokeStyle;
          body.render.sprite.xOffset += -(body.bounds.min.x - body.position.x) / (body.bounds.max.x - body.bounds.min.x);
          body.render.sprite.yOffset += -(body.bounds.min.y - body.position.y) / (body.bounds.max.y - body.bounds.min.y);
      };
  
      /**
       * Given a property and a value (or map of), sets the property(s) on the body, using the appropriate setter functions if they exist.
       * Prefer to use the actual setter functions in performance critical situations.
       * @method set
       * @param {body} body
       * @param {} settings A property name (or map of properties and values) to set on the body.
       * @param {} value The value to set if `settings` is a single property name.
       */
      Body.set = function(body, settings, value) {
          var property;
  
          if (typeof settings === 'string') {
              property = settings;
              settings = {};
              settings[property] = value;
          }
  
          for (property in settings) {
              value = settings[property];
  
              if (!settings.hasOwnProperty(property))
                  continue;
  
              switch (property) {
  
              case 'isStatic':
                  Body.setStatic(body, value);
                  break;
              case 'isSleeping':
                  Sleeping.set(body, value);
                  break;
              case 'mass':
                  Body.setMass(body, value);
                  break;
              case 'density':
                  Body.setDensity(body, value);
                  break;
              case 'inertia':
                  Body.setInertia(body, value);
                  break;
              case 'vertices':
                  Body.setVertices(body, value);
                  break;
              case 'position':
                  Body.setPosition(body, value);
                  break;
              case 'angle':
                  Body.setAngle(body, value);
                  break;
              case 'velocity':
                  Body.setVelocity(body, value);
                  break;
              case 'angularVelocity':
                  Body.setAngularVelocity(body, value);
                  break;
              case 'parts':
                  Body.setParts(body, value);
                  break;
              default:
                  body[property] = value;
  
              }
          }
      };
  
      /**
       * Sets the body as static, including isStatic flag and setting mass and inertia to Infinity.
       * @method setStatic
       * @param {body} body
       * @param {bool} isStatic
       */
      Body.setStatic = function(body, isStatic) {
          for (var i = 0; i < body.parts.length; i++) {
              var part = body.parts[i];
              part.isStatic = isStatic;
  
              if (isStatic) {
                  part.restitution = 0;
                  part.friction = 1;
                  part.mass = part.inertia = part.density = Infinity;
                  part.inverseMass = part.inverseInertia = 0;
  
                  part.positionPrev.x = part.position.x;
                  part.positionPrev.y = part.position.y;
                  part.anglePrev = part.angle;
                  part.angularVelocity = 0;
                  part.speed = 0;
                  part.angularSpeed = 0;
                  part.motion = 0;
              }
          }
      };
  
      /**
       * Sets the mass of the body. Inverse mass and density are automatically updated to reflect the change.
       * @method setMass
       * @param {body} body
       * @param {number} mass
       */
      Body.setMass = function(body, mass) {
          body.mass = mass;
          body.inverseMass = 1 / body.mass;
          body.density = body.mass / body.area;
      };
  
      /**
       * Sets the density of the body. Mass is automatically updated to reflect the change.
       * @method setDensity
       * @param {body} body
       * @param {number} density
       */
      Body.setDensity = function(body, density) {
          Body.setMass(body, density * body.area);
          body.density = density;
      };
  
      /**
       * Sets the moment of inertia (i.e. second moment of area) of the body of the body. 
       * Inverse inertia is automatically updated to reflect the change. Mass is not changed.
       * @method setInertia
       * @param {body} body
       * @param {number} inertia
       */
      Body.setInertia = function(body, inertia) {
          body.inertia = inertia;
          body.inverseInertia = 1 / body.inertia;
      };
  
      /**
       * Sets the body's vertices and updates body properties accordingly, including inertia, area and mass (with respect to `body.density`).
       * Vertices will be automatically transformed to be orientated around their centre of mass as the origin.
       * They are then automatically translated to world space based on `body.position`.
       *
       * The `vertices` argument should be passed as an array of `Matter.Vector` points (or a `Matter.Vertices` array).
       * Vertices must form a convex hull, concave hulls are not supported.
       *
       * @method setVertices
       * @param {body} body
       * @param {vector[]} vertices
       */
      Body.setVertices = function(body, vertices) {
          // change vertices
          if (vertices[0].body === body) {
              body.vertices = vertices;
          } else {
              body.vertices = Vertices.create(vertices, body);
          }
  
          // update properties
          body.axes = Axes.fromVertices(body.vertices);
          body.area = Vertices.area(body.vertices);
          Body.setMass(body, body.density * body.area);
  
          // orient vertices around the centre of mass at origin (0, 0)
          var centre = Vertices.centre(body.vertices);
          Vertices.translate(body.vertices, centre, -1);
  
          // update inertia while vertices are at origin (0, 0)
          Body.setInertia(body, Body._inertiaScale * Vertices.inertia(body.vertices, body.mass));
  
          // update geometry
          Vertices.translate(body.vertices, body.position);
          Bounds.update(body.bounds, body.vertices, body.velocity);
      };
  
      /**
       * Sets the parts of the `body` and updates mass, inertia and centroid.
       * Each part will have its parent set to `body`.
       * By default the convex hull will be automatically computed and set on `body`, unless `autoHull` is set to `false.`
       * Note that this method will ensure that the first part in `body.parts` will always be the `body`.
       * @method setParts
       * @param {body} body
       * @param [body] parts
       * @param {bool} [autoHull=true]
       */
      Body.setParts = function(body, parts, autoHull) {
          var i;
  
          // add all the parts, ensuring that the first part is always the parent body
          parts = parts.slice(0);
          body.parts.length = 0;
          body.parts.push(body);
          body.parent = body;
  
          for (i = 0; i < parts.length; i++) {
              var part = parts[i];
              if (part !== body) {
                  part.parent = body;
                  body.parts.push(part);
              }
          }
  
          if (body.parts.length === 1)
              return;
  
          autoHull = typeof autoHull !== 'undefined' ? autoHull : true;
  
          // find the convex hull of all parts to set on the parent body
          if (autoHull) {
              var vertices = [];
              for (i = 0; i < parts.length; i++) {
                  vertices = vertices.concat(parts[i].vertices);
              }
  
              Vertices.clockwiseSort(vertices);
  
              var hull = Vertices.hull(vertices),
                  hullCentre = Vertices.centre(hull);
  
              Body.setVertices(body, hull);
              Vertices.translate(body.vertices, hullCentre);
          }
  
          // sum the properties of all compound parts of the parent body
          var total = _totalProperties(body);
  
          body.area = total.area;
          body.parent = body;
          body.position.x = total.centre.x;
          body.position.y = total.centre.y;
          body.positionPrev.x = total.centre.x;
          body.positionPrev.y = total.centre.y;
  
          Body.setMass(body, total.mass);
          Body.setInertia(body, total.inertia);
          Body.setPosition(body, total.centre);
      };
  
      /**
       * Sets the position of the body instantly. Velocity, angle, force etc. are unchanged.
       * @method setPosition
       * @param {body} body
       * @param {vector} position
       */
      Body.setPosition = function(body, position) {
          var delta = Vector.sub(position, body.position);
          body.positionPrev.x += delta.x;
          body.positionPrev.y += delta.y;
  
          for (var i = 0; i < body.parts.length; i++) {
              var part = body.parts[i];
              part.position.x += delta.x;
              part.position.y += delta.y;
              Vertices.translate(part.vertices, delta);
              Bounds.update(part.bounds, part.vertices, body.velocity);
          }
      };
  
      /**
       * Sets the angle of the body instantly. Angular velocity, position, force etc. are unchanged.
       * @method setAngle
       * @param {body} body
       * @param {number} angle
       */
      Body.setAngle = function(body, angle) {
          var delta = angle - body.angle;
          body.anglePrev += delta;
  
          for (var i = 0; i < body.parts.length; i++) {
              var part = body.parts[i];
              part.angle += delta;
              Vertices.rotate(part.vertices, delta, body.position);
              Axes.rotate(part.axes, delta);
              Bounds.update(part.bounds, part.vertices, body.velocity);
              if (i > 0) {
                  Vector.rotateAbout(part.position, delta, body.position, part.position);
              }
          }
      };
  
      /**
       * Sets the linear velocity of the body instantly. Position, angle, force etc. are unchanged. See also `Body.applyForce`.
       * @method setVelocity
       * @param {body} body
       * @param {vector} velocity
       */
      Body.setVelocity = function(body, velocity) {
          body.positionPrev.x = body.position.x - velocity.x;
          body.positionPrev.y = body.position.y - velocity.y;
          body.velocity.x = velocity.x;
          body.velocity.y = velocity.y;
          body.speed = Vector.magnitude(body.velocity);
      };
  
      /**
       * Sets the angular velocity of the body instantly. Position, angle, force etc. are unchanged. See also `Body.applyForce`.
       * @method setAngularVelocity
       * @param {body} body
       * @param {number} velocity
       */
      Body.setAngularVelocity = function(body, velocity) {
          body.anglePrev = body.angle - velocity;
          body.angularVelocity = velocity;
          body.angularSpeed = Math.abs(body.angularVelocity);
      };
  
      /**
       * Moves a body by a given vector relative to its current position, without imparting any velocity.
       * @method translate
       * @param {body} body
       * @param {vector} translation
       */
      Body.translate = function(body, translation) {
          Body.setPosition(body, Vector.add(body.position, translation));
      };
  
      /**
       * Rotates a body by a given angle relative to its current angle, without imparting any angular velocity.
       * @method rotate
       * @param {body} body
       * @param {number} rotation
       */
      Body.rotate = function(body, rotation) {
          Body.setAngle(body, body.angle + rotation);
      };
  
      /**
       * Scales the body, including updating physical properties (mass, area, axes, inertia), from a world-space point (default is body centre).
       * @method scale
       * @param {body} body
       * @param {number} scaleX
       * @param {number} scaleY
       * @param {vector} [point]
       */
      Body.scale = function(body, scaleX, scaleY, point) {
          for (var i = 0; i < body.parts.length; i++) {
              var part = body.parts[i];
  
              // scale vertices
              Vertices.scale(part.vertices, scaleX, scaleY, body.position);
  
              // update properties
              part.axes = Axes.fromVertices(part.vertices);
  
              if (!body.isStatic) {
                  part.area = Vertices.area(part.vertices);
                  Body.setMass(part, body.density * part.area);
  
                  // update inertia (requires vertices to be at origin)
                  Vertices.translate(part.vertices, { x: -part.position.x, y: -part.position.y });
                  Body.setInertia(part, Vertices.inertia(part.vertices, part.mass));
                  Vertices.translate(part.vertices, { x: part.position.x, y: part.position.y });
              }
  
              // update bounds
              Bounds.update(part.bounds, part.vertices, body.velocity);
          }
  
          if (!body.isStatic) {
              var total = _totalProperties(body);
              body.area = total.area;
              Body.setMass(body, total.mass);
              Body.setInertia(body, total.inertia);
          }
      };
  
      /**
       * Performs a simulation step for the given `body`, including updating position and angle using Verlet integration.
       * @method update
       * @param {body} body
       * @param {number} deltaTime
       * @param {number} timeScale
       * @param {number} correction
       */
      Body.update = function(body, deltaTime, timeScale, correction) {
          var deltaTimeSquared = Math.pow(deltaTime * timeScale * body.timeScale, 2);
  
          // from the previous step
          var frictionAir = 1 - body.frictionAir * timeScale * body.timeScale,
              velocityPrevX = body.position.x - body.positionPrev.x,
              velocityPrevY = body.position.y - body.positionPrev.y;
  
          // update velocity with Verlet integration
          body.velocity.x = (velocityPrevX * frictionAir * correction) + (body.force.x / body.mass) * deltaTimeSquared;
          body.velocity.y = (velocityPrevY * frictionAir * correction) + (body.force.y / body.mass) * deltaTimeSquared;
  
          body.positionPrev.x = body.position.x;
          body.positionPrev.y = body.position.y;
          body.position.x += body.velocity.x;
          body.position.y += body.velocity.y;
  
          // update angular velocity with Verlet integration
          body.angularVelocity = ((body.angle - body.anglePrev) * frictionAir * correction) + (body.torque / body.inertia) * deltaTimeSquared;
          body.anglePrev = body.angle;
          body.angle += body.angularVelocity;
  
          // track speed and acceleration
          body.speed = Vector.magnitude(body.velocity);
          body.angularSpeed = Math.abs(body.angularVelocity);
  
          // transform the body geometry
          for (var i = 0; i < body.parts.length; i++) {
              var part = body.parts[i];
  
              Vertices.translate(part.vertices, body.velocity);
              
              if (i > 0) {
                  part.position.x += body.velocity.x;
                  part.position.y += body.velocity.y;
              }
  
              if (body.angularVelocity !== 0) {
                  Vertices.rotate(part.vertices, body.angularVelocity, body.position);
                  Axes.rotate(part.axes, body.angularVelocity);
                  if (i > 0) {
                      Vector.rotateAbout(part.position, body.angularVelocity, body.position, part.position);
                  }
              }
  
              Bounds.update(part.bounds, part.vertices, body.velocity);
          }
      };
  
      /**
       * Applies a force to a body from a given world-space position, including resulting torque.
       * @method applyForce
       * @param {body} body
       * @param {vector} position
       * @param {vector} force
       */
      Body.applyForce = function(body, position, force) {
          body.force.x += force.x;
          body.force.y += force.y;
          var offset = { x: position.x - body.position.x, y: position.y - body.position.y };
          body.torque += offset.x * force.y - offset.y * force.x;
      };
  
      /**
       * Returns the sums of the properties of all compound parts of the parent body.
       * @method _totalProperties
       * @private
       * @param {body} body
       * @return {}
       */
      var _totalProperties = function(body) {
          // https://ecourses.ou.edu/cgi-bin/ebook.cgi?doc=&topic=st&chap_sec=07.2&page=theory
          // http://output.to/sideway/default.asp?qno=121100087
  
          var properties = {
              mass: 0,
              area: 0,
              inertia: 0,
              centre: { x: 0, y: 0 }
          };
  
          // sum the properties of all compound parts of the parent body
          for (var i = body.parts.length === 1 ? 0 : 1; i < body.parts.length; i++) {
              var part = body.parts[i];
              properties.mass += part.mass;
              properties.area += part.area;
              properties.inertia += part.inertia;
              properties.centre = Vector.add(properties.centre, 
                                             Vector.mult(part.position, part.mass !== Infinity ? part.mass : 1));
          }
  
          properties.centre = Vector.div(properties.centre, 
                                         properties.mass !== Infinity ? properties.mass : body.parts.length);
  
          return properties;
      };
  
      /*
      *
      *  Events Documentation
      *
      */
  
      /**
      * Fired when a body starts sleeping (where `this` is the body).
      *
      * @event sleepStart
      * @this {body} The body that has started sleeping
      * @param {} event An event object
      * @param {} event.source The source object of the event
      * @param {} event.name The name of the event
      */
  
      /**
      * Fired when a body ends sleeping (where `this` is the body).
      *
      * @event sleepEnd
      * @this {body} The body that has ended sleeping
      * @param {} event An event object
      * @param {} event.source The source object of the event
      * @param {} event.name The name of the event
      */
  
      /*
      *
      *  Properties Documentation
      *
      */
  
      /**
       * An integer `Number` uniquely identifying number generated in `Body.create` by `Common.nextId`.
       *
       * @property id
       * @type number
       */
  
      /**
       * A `String` denoting the type of object.
       *
       * @property type
       * @type string
       * @default "body"
       */
  
      /**
       * An arbitrary `String` name to help the user identify and manage bodies.
       *
       * @property label
       * @type string
       * @default "Body"
       */
  
      /**
       * An array of bodies that make up this body. 
       * The first body in the array must always be a self reference to the current body instance.
       * All bodies in the `parts` array together form a single rigid compound body.
       * Parts are allowed to overlap, have gaps or holes or even form concave bodies.
       * Parts themselves should never be added to a `World`, only the parent body should be.
       * Use `Body.setParts` when setting parts to ensure correct updates of all properties.
       *
       * @property parts
       * @type body[]
       */
  
      /**
       * A self reference if the body is _not_ a part of another body.
       * Otherwise this is a reference to the body that this is a part of.
       * See `body.parts`.
       *
       * @property parent
       * @type body
       */
  
      /**
       * A `Number` specifying the angle of the body, in radians.
       *
       * @property angle
       * @type number
       * @default 0
       */
  
      /**
       * An array of `Vector` objects that specify the convex hull of the rigid body.
       * These should be provided about the origin `(0, 0)`. E.g.
       *
       *     [{ x: 0, y: 0 }, { x: 25, y: 50 }, { x: 50, y: 0 }]
       *
       * When passed via `Body.create`, the vertices are translated relative to `body.position` (i.e. world-space, and constantly updated by `Body.update` during simulation).
       * The `Vector` objects are also augmented with additional properties required for efficient collision detection. 
       *
       * Other properties such as `inertia` and `bounds` are automatically calculated from the passed vertices (unless provided via `options`).
       * Concave hulls are not currently supported. The module `Matter.Vertices` contains useful methods for working with vertices.
       *
       * @property vertices
       * @type vector[]
       */
  
      /**
       * A `Vector` that specifies the current world-space position of the body.
       *
       * @property position
       * @type vector
       * @default { x: 0, y: 0 }
       */
  
      /**
       * A `Vector` that specifies the force to apply in the current step. It is zeroed after every `Body.update`. See also `Body.applyForce`.
       *
       * @property force
       * @type vector
       * @default { x: 0, y: 0 }
       */
  
      /**
       * A `Number` that specifies the torque (turning force) to apply in the current step. It is zeroed after every `Body.update`.
       *
       * @property torque
       * @type number
       * @default 0
       */
  
      /**
       * A `Number` that _measures_ the current speed of the body after the last `Body.update`. It is read-only and always positive (it's the magnitude of `body.velocity`).
       *
       * @readOnly
       * @property speed
       * @type number
       * @default 0
       */
  
      /**
       * A `Number` that _measures_ the current angular speed of the body after the last `Body.update`. It is read-only and always positive (it's the magnitude of `body.angularVelocity`).
       *
       * @readOnly
       * @property angularSpeed
       * @type number
       * @default 0
       */
  
      /**
       * A `Vector` that _measures_ the current velocity of the body after the last `Body.update`. It is read-only. 
       * If you need to modify a body's velocity directly, you should either apply a force or simply change the body's `position` (as the engine uses position-Verlet integration).
       *
       * @readOnly
       * @property velocity
       * @type vector
       * @default { x: 0, y: 0 }
       */
  
      /**
       * A `Number` that _measures_ the current angular velocity of the body after the last `Body.update`. It is read-only. 
       * If you need to modify a body's angular velocity directly, you should apply a torque or simply change the body's `angle` (as the engine uses position-Verlet integration).
       *
       * @readOnly
       * @property angularVelocity
       * @type number
       * @default 0
       */
  
      /**
       * A flag that indicates whether a body is considered static. A static body can never change position or angle and is completely fixed.
       * If you need to set a body as static after its creation, you should use `Body.setStatic` as this requires more than just setting this flag.
       *
       * @property isStatic
       * @type boolean
       * @default false
       */
  
      /**
       * A flag that indicates whether the body is considered sleeping. A sleeping body acts similar to a static body, except it is only temporary and can be awoken.
       * If you need to set a body as sleeping, you should use `Sleeping.set` as this requires more than just setting this flag.
       *
       * @property isSleeping
       * @type boolean
       * @default false
       */
  
      /**
       * A `Number` that _measures_ the amount of movement a body currently has (a combination of `speed` and `angularSpeed`). It is read-only and always positive.
       * It is used and updated by the `Matter.Sleeping` module during simulation to decide if a body has come to rest.
       *
       * @readOnly
       * @property motion
       * @type number
       * @default 0
       */
  
      /**
       * A `Number` that defines the number of updates in which this body must have near-zero velocity before it is set as sleeping by the `Matter.Sleeping` module (if sleeping is enabled by the engine).
       *
       * @property sleepThreshold
       * @type number
       * @default 60
       */
  
      /**
       * A `Number` that defines the density of the body, that is its mass per unit area.
       * If you pass the density via `Body.create` the `mass` property is automatically calculated for you based on the size (area) of the object.
       * This is generally preferable to simply setting mass and allows for more intuitive definition of materials (e.g. rock has a higher density than wood).
       *
       * @property density
       * @type number
       * @default 0.001
       */
  
      /**
       * A `Number` that defines the mass of the body, although it may be more appropriate to specify the `density` property instead.
       * If you modify this value, you must also modify the `body.inverseMass` property (`1 / mass`).
       *
       * @property mass
       * @type number
       */
  
      /**
       * A `Number` that defines the inverse mass of the body (`1 / mass`).
       * If you modify this value, you must also modify the `body.mass` property.
       *
       * @property inverseMass
       * @type number
       */
  
      /**
       * A `Number` that defines the moment of inertia (i.e. second moment of area) of the body.
       * It is automatically calculated from the given convex hull (`vertices` array) and density in `Body.create`.
       * If you modify this value, you must also modify the `body.inverseInertia` property (`1 / inertia`).
       *
       * @property inertia
       * @type number
       */
  
      /**
       * A `Number` that defines the inverse moment of inertia of the body (`1 / inertia`).
       * If you modify this value, you must also modify the `body.inertia` property.
       *
       * @property inverseInertia
       * @type number
       */
  
      /**
       * A `Number` that defines the restitution (elasticity) of the body. The value is always positive and is in the range `(0, 1)`.
       * A value of `0` means collisions may be perfectly inelastic and no bouncing may occur. 
       * A value of `0.8` means the body may bounce back with approximately 80% of its kinetic energy.
       * Note that collision response is based on _pairs_ of bodies, and that `restitution` values are _combined_ with the following formula:
       *
       *     Math.max(bodyA.restitution, bodyB.restitution)
       *
       * @property restitution
       * @type number
       * @default 0
       */
  
      /**
       * A `Number` that defines the friction of the body. The value is always positive and is in the range `(0, 1)`.
       * A value of `0` means that the body may slide indefinitely.
       * A value of `1` means the body may come to a stop almost instantly after a force is applied.
       *
       * The effects of the value may be non-linear. 
       * High values may be unstable depending on the body.
       * The engine uses a Coulomb friction model including static and kinetic friction.
       * Note that collision response is based on _pairs_ of bodies, and that `friction` values are _combined_ with the following formula:
       *
       *     Math.min(bodyA.friction, bodyB.friction)
       *
       * @property friction
       * @type number
       * @default 0.1
       */
  
      /**
       * A `Number` that defines the static friction of the body (in the Coulomb friction model). 
       * A value of `0` means the body will never 'stick' when it is nearly stationary and only dynamic `friction` is used.
       * The higher the value (e.g. `10`), the more force it will take to initially get the body moving when nearly stationary.
       * This value is multiplied with the `friction` property to make it easier to change `friction` and maintain an appropriate amount of static friction.
       *
       * @property frictionStatic
       * @type number
       * @default 0.5
       */
  
      /**
       * A `Number` that defines the air friction of the body (air resistance). 
       * A value of `0` means the body will never slow as it moves through space.
       * The higher the value, the faster a body slows when moving through space.
       * The effects of the value are non-linear. 
       *
       * @property frictionAir
       * @type number
       * @default 0.01
       */
  
      /**
       * An `Object` that specifies the collision filtering properties of this body.
       *
       * Collisions between two bodies will obey the following rules:
       * - If the two bodies have the same non-zero value of `collisionFilter.group`,
       *   they will always collide if the value is positive, and they will never collide
       *   if the value is negative.
       * - If the two bodies have different values of `collisionFilter.group` or if one
       *   (or both) of the bodies has a value of 0, then the category/mask rules apply as follows:
       *
       * Each body belongs to a collision category, given by `collisionFilter.category`. This
       * value is used as a bit field and the category should have only one bit set, meaning that
       * the value of this property is a power of two in the range [1, 2^31]. Thus, there are 32
       * different collision categories available.
       *
       * Each body also defines a collision bitmask, given by `collisionFilter.mask` which specifies
       * the categories it collides with (the value is the bitwise AND value of all these categories).
       *
       * Using the category/mask rules, two bodies `A` and `B` collide if each includes the other's
       * category in its mask, i.e. `(categoryA & maskB) !== 0` and `(categoryB & maskA) !== 0`
       * are both true.
       *
       * @property collisionFilter
       * @type object
       */
  
      /**
       * An Integer `Number`, that specifies the collision group this body belongs to.
       * See `body.collisionFilter` for more information.
       *
       * @property collisionFilter.group
       * @type object
       * @default 0
       */
  
      /**
       * A bit field that specifies the collision category this body belongs to.
       * The category value should have only one bit set, for example `0x0001`.
       * This means there are up to 32 unique collision categories available.
       * See `body.collisionFilter` for more information.
       *
       * @property collisionFilter.category
       * @type object
       * @default 1
       */
  
      /**
       * A bit mask that specifies the collision categories this body may collide with.
       * See `body.collisionFilter` for more information.
       *
       * @property collisionFilter.mask
       * @type object
       * @default -1
       */
  
      /**
       * A `Number` that specifies a tolerance on how far a body is allowed to 'sink' or rotate into other bodies.
       * Avoid changing this value unless you understand the purpose of `slop` in physics engines.
       * The default should generally suffice, although very large bodies may require larger values for stable stacking.
       *
       * @property slop
       * @type number
       * @default 0.05
       */
  
      /**
       * A `Number` that allows per-body time scaling, e.g. a force-field where bodies inside are in slow-motion, while others are at full speed.
       *
       * @property timeScale
       * @type number
       * @default 1
       */
  
      /**
       * An `Object` that defines the rendering properties to be consumed by the module `Matter.Render`.
       *
       * @property render
       * @type object
       */
  
      /**
       * A flag that indicates if the body should be rendered.
       *
       * @property render.visible
       * @type boolean
       * @default true
       */
  
      /**
       * An `Object` that defines the sprite properties to use when rendering, if any.
       *
       * @property render.sprite
       * @type object
       */
  
      /**
       * An `String` that defines the path to the image to use as the sprite texture, if any.
       *
       * @property render.sprite.texture
       * @type string
       */
       
      /**
       * A `Number` that defines the scaling in the x-axis for the sprite, if any.
       *
       * @property render.sprite.xScale
       * @type number
       * @default 1
       */
  
      /**
       * A `Number` that defines the scaling in the y-axis for the sprite, if any.
       *
       * @property render.sprite.yScale
       * @type number
       * @default 1
       */
  
       /**
        * A `Number` that defines the offset in the x-axis for the sprite (normalised by texture width).
        *
        * @property render.sprite.xOffset
        * @type number
        * @default 0
        */
  
       /**
        * A `Number` that defines the offset in the y-axis for the sprite (normalised by texture height).
        *
        * @property render.sprite.yOffset
        * @type number
        * @default 0
        */
  
      /**
       * A `Number` that defines the line width to use when rendering the body outline (if a sprite is not defined).
       * A value of `0` means no outline will be rendered.
       *
       * @property render.lineWidth
       * @type number
       * @default 1.5
       */
  
      /**
       * A `String` that defines the fill style to use when rendering the body (if a sprite is not defined).
       * It is the same as when using a canvas, so it accepts CSS style property values.
       *
       * @property render.fillStyle
       * @type string
       * @default a random colour
       */
  
      /**
       * A `String` that defines the stroke style to use when rendering the body outline (if a sprite is not defined).
       * It is the same as when using a canvas, so it accepts CSS style property values.
       *
       * @property render.strokeStyle
       * @type string
       * @default a random colour
       */
  
      /**
       * An array of unique axis vectors (edge normals) used for collision detection.
       * These are automatically calculated from the given convex hull (`vertices` array) in `Body.create`.
       * They are constantly updated by `Body.update` during the simulation.
       *
       * @property axes
       * @type vector[]
       */
       
      /**
       * A `Number` that _measures_ the area of the body's convex hull, calculated at creation by `Body.create`.
       *
       * @property area
       * @type string
       * @default 
       */
  
      /**
       * A `Bounds` object that defines the AABB region for the body.
       * It is automatically calculated from the given convex hull (`vertices` array) in `Body.create` and constantly updated by `Body.update` during simulation.
       *
       * @property bounds
       * @type bounds
       */
  
  })();
  
  },{"../core/Common":14,"../core/Sleeping":20,"../geometry/Axes":23,"../geometry/Bounds":24,"../geometry/Vector":26,"../geometry/Vertices":27,"../render/Render":29}],2:[function(require,module,exports){
  /**
  * The `Matter.Composite` module contains methods for creating and manipulating composite bodies.
  * A composite body is a collection of `Matter.Body`, `Matter.Constraint` and other `Matter.Composite`, therefore composites form a tree structure.
  * It is important to use the functions in this module to modify composites, rather than directly modifying their properties.
  * Note that the `Matter.World` object is also a type of `Matter.Composite` and as such all composite methods here can also operate on a `Matter.World`.
  *
  * See the included usage [examples](https://github.com/liabru/matter-js/tree/master/examples).
  *
  * @class Composite
  */
  
  var Composite = {};
  
  module.exports = Composite;
  
  var Events = require('../core/Events');
  var Common = require('../core/Common');
  var Body = require('./Body');
  
  (function() {
  
      /**
       * Creates a new composite. The options parameter is an object that specifies any properties you wish to override the defaults.
       * See the properites section below for detailed information on what you can pass via the `options` object.
       * @method create
       * @param {} [options]
       * @return {composite} A new composite
       */
      Composite.create = function(options) {
          return Common.extend({ 
              id: Common.nextId(),
              type: 'composite',
              parent: null,
              isModified: false,
              bodies: [], 
              constraints: [], 
              composites: [],
              label: 'Composite'
          }, options);
      };
  
      /**
       * Sets the composite's `isModified` flag. 
       * If `updateParents` is true, all parents will be set (default: false).
       * If `updateChildren` is true, all children will be set (default: false).
       * @method setModified
       * @param {composite} composite
       * @param {boolean} isModified
       * @param {boolean} [updateParents=false]
       * @param {boolean} [updateChildren=false]
       */
      Composite.setModified = function(composite, isModified, updateParents, updateChildren) {
          composite.isModified = isModified;
  
          if (updateParents && composite.parent) {
              Composite.setModified(composite.parent, isModified, updateParents, updateChildren);
          }
  
          if (updateChildren) {
              for(var i = 0; i < composite.composites.length; i++) {
                  var childComposite = composite.composites[i];
                  Composite.setModified(childComposite, isModified, updateParents, updateChildren);
              }
          }
      };
  
      /**
       * Generic add function. Adds one or many body(s), constraint(s) or a composite(s) to the given composite.
       * Triggers `beforeAdd` and `afterAdd` events on the `composite`.
       * @method add
       * @param {composite} composite
       * @param {} object
       * @return {composite} The original composite with the objects added
       */
      Composite.add = function(composite, object) {
          var objects = [].concat(object);
  
          Events.trigger(composite, 'beforeAdd', { object: object });
  
          for (var i = 0; i < objects.length; i++) {
              var obj = objects[i];
  
              switch (obj.type) {
  
              case 'body':
                  // skip adding compound parts
                  if (obj.parent !== obj) {
                      Common.log('Composite.add: skipped adding a compound body part (you must add its parent instead)', 'warn');
                      break;
                  }
  
                  Composite.addBody(composite, obj);
                  break;
              case 'constraint':
                  Composite.addConstraint(composite, obj);
                  break;
              case 'composite':
                  Composite.addComposite(composite, obj);
                  break;
              case 'mouseConstraint':
                  Composite.addConstraint(composite, obj.constraint);
                  break;
  
              }
          }
  
          Events.trigger(composite, 'afterAdd', { object: object });
  
          return composite;
      };
  
      /**
       * Generic remove function. Removes one or many body(s), constraint(s) or a composite(s) to the given composite.
       * Optionally searching its children recursively.
       * Triggers `beforeRemove` and `afterRemove` events on the `composite`.
       * @method remove
       * @param {composite} composite
       * @param {} object
       * @param {boolean} [deep=false]
       * @return {composite} The original composite with the objects removed
       */
      Composite.remove = function(composite, object, deep) {
          var objects = [].concat(object);
  
          Events.trigger(composite, 'beforeRemove', { object: object });
  
          for (var i = 0; i < objects.length; i++) {
              var obj = objects[i];
  
              switch (obj.type) {
  
              case 'body':
                  Composite.removeBody(composite, obj, deep);
                  break;
              case 'constraint':
                  Composite.removeConstraint(composite, obj, deep);
                  break;
              case 'composite':
                  Composite.removeComposite(composite, obj, deep);
                  break;
              case 'mouseConstraint':
                  Composite.removeConstraint(composite, obj.constraint);
                  break;
  
              }
          }
  
          Events.trigger(composite, 'afterRemove', { object: object });
  
          return composite;
      };
  
      /**
       * Adds a composite to the given composite.
       * @private
       * @method addComposite
       * @param {composite} compositeA
       * @param {composite} compositeB
       * @return {composite} The original compositeA with the objects from compositeB added
       */
      Composite.addComposite = function(compositeA, compositeB) {
          compositeA.composites.push(compositeB);
          compositeB.parent = compositeA;
          Composite.setModified(compositeA, true, true, false);
          return compositeA;
      };
  
      /**
       * Removes a composite from the given composite, and optionally searching its children recursively.
       * @private
       * @method removeComposite
       * @param {composite} compositeA
       * @param {composite} compositeB
       * @param {boolean} [deep=false]
       * @return {composite} The original compositeA with the composite removed
       */
      Composite.removeComposite = function(compositeA, compositeB, deep) {
          var position = Common.indexOf(compositeA.composites, compositeB);
          if (position !== -1) {
              Composite.removeCompositeAt(compositeA, position);
              Composite.setModified(compositeA, true, true, false);
          }
  
          if (deep) {
              for (var i = 0; i < compositeA.composites.length; i++){
                  Composite.removeComposite(compositeA.composites[i], compositeB, true);
              }
          }
  
          return compositeA;
      };
  
      /**
       * Removes a composite from the given composite.
       * @private
       * @method removeCompositeAt
       * @param {composite} composite
       * @param {number} position
       * @return {composite} The original composite with the composite removed
       */
      Composite.removeCompositeAt = function(composite, position) {
          composite.composites.splice(position, 1);
          Composite.setModified(composite, true, true, false);
          return composite;
      };
  
      /**
       * Adds a body to the given composite.
       * @private
       * @method addBody
       * @param {composite} composite
       * @param {body} body
       * @return {composite} The original composite with the body added
       */
      Composite.addBody = function(composite, body) {
          composite.bodies.push(body);
          Composite.setModified(composite, true, true, false);
          return composite;
      };
  
      /**
       * Removes a body from the given composite, and optionally searching its children recursively.
       * @private
       * @method removeBody
       * @param {composite} composite
       * @param {body} body
       * @param {boolean} [deep=false]
       * @return {composite} The original composite with the body removed
       */
      Composite.removeBody = function(composite, body, deep) {
          var position = Common.indexOf(composite.bodies, body);
          if (position !== -1) {
              Composite.removeBodyAt(composite, position);
              Composite.setModified(composite, true, true, false);
          }
  
          if (deep) {
              for (var i = 0; i < composite.composites.length; i++){
                  Composite.removeBody(composite.composites[i], body, true);
              }
          }
  
          return composite;
      };
  
      /**
       * Removes a body from the given composite.
       * @private
       * @method removeBodyAt
       * @param {composite} composite
       * @param {number} position
       * @return {composite} The original composite with the body removed
       */
      Composite.removeBodyAt = function(composite, position) {
          composite.bodies.splice(position, 1);
          Composite.setModified(composite, true, true, false);
          return composite;
      };
  
      /**
       * Adds a constraint to the given composite.
       * @private
       * @method addConstraint
       * @param {composite} composite
       * @param {constraint} constraint
       * @return {composite} The original composite with the constraint added
       */
      Composite.addConstraint = function(composite, constraint) {
          composite.constraints.push(constraint);
          Composite.setModified(composite, true, true, false);
          return composite;
      };
  
      /**
       * Removes a constraint from the given composite, and optionally searching its children recursively.
       * @private
       * @method removeConstraint
       * @param {composite} composite
       * @param {constraint} constraint
       * @param {boolean} [deep=false]
       * @return {composite} The original composite with the constraint removed
       */
      Composite.removeConstraint = function(composite, constraint, deep) {
          var position = Common.indexOf(composite.constraints, constraint);
          if (position !== -1) {
              Composite.removeConstraintAt(composite, position);
          }
  
          if (deep) {
              for (var i = 0; i < composite.composites.length; i++){
                  Composite.removeConstraint(composite.composites[i], constraint, true);
              }
          }
  
          return composite;
      };
  
      /**
       * Removes a body from the given composite.
       * @private
       * @method removeConstraintAt
       * @param {composite} composite
       * @param {number} position
       * @return {composite} The original composite with the constraint removed
       */
      Composite.removeConstraintAt = function(composite, position) {
          composite.constraints.splice(position, 1);
          Composite.setModified(composite, true, true, false);
          return composite;
      };
  
      /**
       * Removes all bodies, constraints and composites from the given composite.
       * Optionally clearing its children recursively.
       * @method clear
       * @param {composite} composite
       * @param {boolean} keepStatic
       * @param {boolean} [deep=false]
       */
      Composite.clear = function(composite, keepStatic, deep) {
          if (deep) {
              for (var i = 0; i < composite.composites.length; i++){
                  Composite.clear(composite.composites[i], keepStatic, true);
              }
          }
          
          if (keepStatic) {
              composite.bodies = composite.bodies.filter(function(body) { return body.isStatic; });
          } else {
              composite.bodies.length = 0;
          }
  
          composite.constraints.length = 0;
          composite.composites.length = 0;
          Composite.setModified(composite, true, true, false);
  
          return composite;
      };
  
      /**
       * Returns all bodies in the given composite, including all bodies in its children, recursively.
       * @method allBodies
       * @param {composite} composite
       * @return {body[]} All the bodies
       */
      Composite.allBodies = function(composite) {
          var bodies = [].concat(composite.bodies);
  
          for (var i = 0; i < composite.composites.length; i++)
              bodies = bodies.concat(Composite.allBodies(composite.composites[i]));
  
          return bodies;
      };
  
      /**
       * Returns all constraints in the given composite, including all constraints in its children, recursively.
       * @method allConstraints
       * @param {composite} composite
       * @return {constraint[]} All the constraints
       */
      Composite.allConstraints = function(composite) {
          var constraints = [].concat(composite.constraints);
  
          for (var i = 0; i < composite.composites.length; i++)
              constraints = constraints.concat(Composite.allConstraints(composite.composites[i]));
  
          return constraints;
      };
  
      /**
       * Returns all composites in the given composite, including all composites in its children, recursively.
       * @method allComposites
       * @param {composite} composite
       * @return {composite[]} All the composites
       */
      Composite.allComposites = function(composite) {
          var composites = [].concat(composite.composites);
  
          for (var i = 0; i < composite.composites.length; i++)
              composites = composites.concat(Composite.allComposites(composite.composites[i]));
  
          return composites;
      };
  
      /**
       * Searches the composite recursively for an object matching the type and id supplied, null if not found.
       * @method get
       * @param {composite} composite
       * @param {number} id
       * @param {string} type
       * @return {object} The requested object, if found
       */
      Composite.get = function(composite, id, type) {
          var objects,
              object;
  
          switch (type) {
          case 'body':
              objects = Composite.allBodies(composite);
              break;
          case 'constraint':
              objects = Composite.allConstraints(composite);
              break;
          case 'composite':
              objects = Composite.allComposites(composite).concat(composite);
              break;
          }
  
          if (!objects)
              return null;
  
          object = objects.filter(function(object) { 
              return object.id.toString() === id.toString(); 
          });
  
          return object.length === 0 ? null : object[0];
      };
  
      /**
       * Moves the given object(s) from compositeA to compositeB (equal to a remove followed by an add).
       * @method move
       * @param {compositeA} compositeA
       * @param {object[]} objects
       * @param {compositeB} compositeB
       * @return {composite} Returns compositeA
       */
      Composite.move = function(compositeA, objects, compositeB) {
          Composite.remove(compositeA, objects);
          Composite.add(compositeB, objects);
          return compositeA;
      };
  
      /**
       * Assigns new ids for all objects in the composite, recursively.
       * @method rebase
       * @param {composite} composite
       * @return {composite} Returns composite
       */
      Composite.rebase = function(composite) {
          var objects = Composite.allBodies(composite)
                          .concat(Composite.allConstraints(composite))
                          .concat(Composite.allComposites(composite));
  
          for (var i = 0; i < objects.length; i++) {
              objects[i].id = Common.nextId();
          }
  
          Composite.setModified(composite, true, true, false);
  
          return composite;
      };
  
      /**
       * Translates all children in the composite by a given vector relative to their current positions, 
       * without imparting any velocity.
       * @method translate
       * @param {composite} composite
       * @param {vector} translation
       * @param {bool} [recursive=true]
       */
      Composite.translate = function(composite, translation, recursive) {
          var bodies = recursive ? Composite.allBodies(composite) : composite.bodies;
  
          for (var i = 0; i < bodies.length; i++) {
              Body.translate(bodies[i], translation);
          }
  
          Composite.setModified(composite, true, true, false);
  
          return composite;
      };
  
      /**
       * Rotates all children in the composite by a given angle about the given point, without imparting any angular velocity.
       * @method rotate
       * @param {composite} composite
       * @param {number} rotation
       * @param {vector} point
       * @param {bool} [recursive=true]
       */
      Composite.rotate = function(composite, rotation, point, recursive) {
          var cos = Math.cos(rotation),
              sin = Math.sin(rotation),
              bodies = recursive ? Composite.allBodies(composite) : composite.bodies;
  
          for (var i = 0; i < bodies.length; i++) {
              var body = bodies[i],
                  dx = body.position.x - point.x,
                  dy = body.position.y - point.y;
                  
              Body.setPosition(body, {
                  x: point.x + (dx * cos - dy * sin),
                  y: point.y + (dx * sin + dy * cos)
              });
  
              Body.rotate(body, rotation);
          }
  
          Composite.setModified(composite, true, true, false);
  
          return composite;
      };
  
      /**
       * Scales all children in the composite, including updating physical properties (mass, area, axes, inertia), from a world-space point.
       * @method scale
       * @param {composite} composite
       * @param {number} scaleX
       * @param {number} scaleY
       * @param {vector} point
       * @param {bool} [recursive=true]
       */
      Composite.scale = function(composite, scaleX, scaleY, point, recursive) {
          var bodies = recursive ? Composite.allBodies(composite) : composite.bodies;
  
          for (var i = 0; i < bodies.length; i++) {
              var body = bodies[i],
                  dx = body.position.x - point.x,
                  dy = body.position.y - point.y;
                  
              Body.setPosition(body, {
                  x: point.x + dx * scaleX,
                  y: point.y + dy * scaleY
              });
  
              Body.scale(body, scaleX, scaleY);
          }
  
          Composite.setModified(composite, true, true, false);
  
          return composite;
      };
  
      /*
      *
      *  Events Documentation
      *
      */
  
      /**
      * Fired when a call to `Composite.add` is made, before objects have been added.
      *
      * @event beforeAdd
      * @param {} event An event object
      * @param {} event.object The object(s) to be added (may be a single body, constraint, composite or a mixed array of these)
      * @param {} event.source The source object of the event
      * @param {} event.name The name of the event
      */
  
      /**
      * Fired when a call to `Composite.add` is made, after objects have been added.
      *
      * @event afterAdd
      * @param {} event An event object
      * @param {} event.object The object(s) that have been added (may be a single body, constraint, composite or a mixed array of these)
      * @param {} event.source The source object of the event
      * @param {} event.name The name of the event
      */
  
      /**
      * Fired when a call to `Composite.remove` is made, before objects have been removed.
      *
      * @event beforeRemove
      * @param {} event An event object
      * @param {} event.object The object(s) to be removed (may be a single body, constraint, composite or a mixed array of these)
      * @param {} event.source The source object of the event
      * @param {} event.name The name of the event
      */
  
      /**
      * Fired when a call to `Composite.remove` is made, after objects have been removed.
      *
      * @event afterRemove
      * @param {} event An event object
      * @param {} event.object The object(s) that have been removed (may be a single body, constraint, composite or a mixed array of these)
      * @param {} event.source The source object of the event
      * @param {} event.name The name of the event
      */
  
      /*
      *
      *  Properties Documentation
      *
      */
  
      /**
       * An integer `Number` uniquely identifying number generated in `Composite.create` by `Common.nextId`.
       *
       * @property id
       * @type number
       */
  
      /**
       * A `String` denoting the type of object.
       *
       * @property type
       * @type string
       * @default "composite"
       */
  
      /**
       * An arbitrary `String` name to help the user identify and manage composites.
       *
       * @property label
       * @type string
       * @default "Composite"
       */
  
      /**
       * A flag that specifies whether the composite has been modified during the current step.
       * Most `Matter.Composite` methods will automatically set this flag to `true` to inform the engine of changes to be handled.
       * If you need to change it manually, you should use the `Composite.setModified` method.
       *
       * @property isModified
       * @type boolean
       * @default false
       */
  
      /**
       * The `Composite` that is the parent of this composite. It is automatically managed by the `Matter.Composite` methods.
       *
       * @property parent
       * @type composite
       * @default null
       */
  
      /**
       * An array of `Body` that are _direct_ children of this composite.
       * To add or remove bodies you should use `Composite.add` and `Composite.remove` methods rather than directly modifying this property.
       * If you wish to recursively find all descendants, you should use the `Composite.allBodies` method.
       *
       * @property bodies
       * @type body[]
       * @default []
       */
  
      /**
       * An array of `Constraint` that are _direct_ children of this composite.
       * To add or remove constraints you should use `Composite.add` and `Composite.remove` methods rather than directly modifying this property.
       * If you wish to recursively find all descendants, you should use the `Composite.allConstraints` method.
       *
       * @property constraints
       * @type constraint[]
       * @default []
       */
  
      /**
       * An array of `Composite` that are _direct_ children of this composite.
       * To add or remove composites you should use `Composite.add` and `Composite.remove` methods rather than directly modifying this property.
       * If you wish to recursively find all descendants, you should use the `Composite.allComposites` method.
       *
       * @property composites
       * @type composite[]
       * @default []
       */
  
  })();
  
  },{"../core/Common":14,"../core/Events":16,"./Body":1}],3:[function(require,module,exports){
  /**
  * The `Matter.World` module contains methods for creating and manipulating the world composite.
  * A `Matter.World` is a `Matter.Composite` body, which is a collection of `Matter.Body`, `Matter.Constraint` and other `Matter.Composite`.
  * A `Matter.World` has a few additional properties including `gravity` and `bounds`.
  * It is important to use the functions in the `Matter.Composite` module to modify the world composite, rather than directly modifying its properties.
  * There are also a few methods here that alias those in `Matter.Composite` for easier readability.
  *
  * See the included usage [examples](https://github.com/liabru/matter-js/tree/master/examples).
  *
  * @class World
  * @extends Composite
  */
  
  var World = {};
  
  module.exports = World;
  
  var Composite = require('./Composite');
  var Constraint = require('../constraint/Constraint');
  var Common = require('../core/Common');
  
  (function() {
  
      /**
       * Creates a new world composite. The options parameter is an object that specifies any properties you wish to override the defaults.
       * See the properties section below for detailed information on what you can pass via the `options` object.
       * @method create
       * @constructor
       * @param {} options
       * @return {world} A new world
       */
      World.create = function(options) {
          var composite = Composite.create();
  
          var defaults = {
              label: 'World',
              gravity: {
                  x: 0,
                  y: 1,
                  scale: 0.001
              },
              bounds: { 
                  min: { x: -Infinity, y: -Infinity }, 
                  max: { x: Infinity, y: Infinity } 
              }
          };
          
          return Common.extend(composite, defaults, options);
      };
  
      /*
      *
      *  Properties Documentation
      *
      */
  
      /**
       * The gravity to apply on the world.
       *
       * @property gravity
       * @type object
       */
  
      /**
       * The gravity x component.
       *
       * @property gravity.x
       * @type object
       * @default 0
       */
  
      /**
       * The gravity y component.
       *
       * @property gravity.y
       * @type object
       * @default 1
       */
  
      /**
       * The gravity scale factor.
       *
       * @property gravity.scale
       * @type object
       * @default 0.001
       */
  
      // World is a Composite body
      // see src/module/Outro.js for these aliases:
      
      /**
       * An alias for Composite.clear
       * @method clear
       * @param {world} world
       * @param {boolean} keepStatic
       */
  
      /**
       * An alias for Composite.add
       * @method addComposite
       * @param {world} world
       * @param {composite} composite
       * @return {world} The original world with the objects from composite added
       */
      
       /**
        * An alias for Composite.addBody
        * @method addBody
        * @param {world} world
        * @param {body} body
        * @return {world} The original world with the body added
        */
  
       /**
        * An alias for Composite.addConstraint
        * @method addConstraint
        * @param {world} world
        * @param {constraint} constraint
        * @return {world} The original world with the constraint added
        */
  
  })();
  
  },{"../constraint/Constraint":12,"../core/Common":14,"./Composite":2}],4:[function(require,module,exports){
  /**
  * The `Matter.Contact` module contains methods for creating and manipulating collision contacts.
  *
  * @class Contact
  */
  
  var Contact = {};
  
  module.exports = Contact;
  
  (function() {
  
      /**
       * Creates a new contact.
       * @method create
       * @param {vertex} vertex
       * @return {contact} A new contact
       */
      Contact.create = function(vertex) {
          return {
              id: Contact.id(vertex),
              vertex: vertex,
              normalImpulse: 0,
              tangentImpulse: 0
          };
      };
      
      /**
       * Generates a contact id.
       * @method id
       * @param {vertex} vertex
       * @return {string} Unique contactID
       */
      Contact.id = function(vertex) {
          return vertex.body.id + '_' + vertex.index;
      };
  
  })();
  
  },{}],5:[function(require,module,exports){
  /**
  * The `Matter.Detector` module contains methods for detecting collisions given a set of pairs.
  *
  * @class Detector
  */
  
  // TODO: speculative contacts
  
  var Detector = {};
  
  module.exports = Detector;
  
  var SAT = require('./SAT');
  var Pair = require('./Pair');
  var Bounds = require('../geometry/Bounds');
  
  (function() {
  
      /**
       * Finds all collisions given a list of pairs.
       * @method collisions
       * @param {pair[]} broadphasePairs
       * @param {engine} engine
       * @return {array} collisions
       */
      Detector.collisions = function(broadphasePairs, engine) {
          var collisions = [],
              pairsTable = engine.pairs.table;
  
          
          for (var i = 0; i < broadphasePairs.length; i++) {
              var bodyA = broadphasePairs[i][0], 
                  bodyB = broadphasePairs[i][1];
  
              if ((bodyA.isStatic || bodyA.isSleeping) && (bodyB.isStatic || bodyB.isSleeping))
                  continue;
              
              if (!Detector.canCollide(bodyA.collisionFilter, bodyB.collisionFilter))
                  continue;
  
  
              // mid phase
              if (Bounds.overlaps(bodyA.bounds, bodyB.bounds)) {
                  for (var j = bodyA.parts.length > 1 ? 1 : 0; j < bodyA.parts.length; j++) {
                      var partA = bodyA.parts[j];
  
                      for (var k = bodyB.parts.length > 1 ? 1 : 0; k < bodyB.parts.length; k++) {
                          var partB = bodyB.parts[k];
  
                          if ((partA === bodyA && partB === bodyB) || Bounds.overlaps(partA.bounds, partB.bounds)) {
                              // find a previous collision we could reuse
                              var pairId = Pair.id(partA, partB),
                                  pair = pairsTable[pairId],
                                  previousCollision;
  
                              if (pair && pair.isActive) {
                                  previousCollision = pair.collision;
                              } else {
                                  previousCollision = null;
                              }
  
                              // narrow phase
                              var collision = SAT.collides(partA, partB, previousCollision);
  
  
                              if (collision.collided) {
                                  collisions.push(collision);
                              }
                          }
                      }
                  }
              }
          }
  
          return collisions;
      };
  
      /**
       * Returns `true` if both supplied collision filters will allow a collision to occur.
       * See `body.collisionFilter` for more information.
       * @method canCollide
       * @param {} filterA
       * @param {} filterB
       * @return {bool} `true` if collision can occur
       */
      Detector.canCollide = function(filterA, filterB) {
          if (filterA.group === filterB.group && filterA.group !== 0)
              return filterA.group > 0;
  
          return (filterA.mask & filterB.category) !== 0 && (filterB.mask & filterA.category) !== 0;
      };
  
  })();
  
  },{"../geometry/Bounds":24,"./Pair":7,"./SAT":11}],6:[function(require,module,exports){
  /**
  * The `Matter.Grid` module contains methods for creating and manipulating collision broadphase grid structures.
  *
  * @class Grid
  */
  
  var Grid = {};
  
  module.exports = Grid;
  
  var Pair = require('./Pair');
  var Detector = require('./Detector');
  var Common = require('../core/Common');
  
  (function() {
  
      /**
       * Creates a new grid.
       * @method create
       * @param {} options
       * @return {grid} A new grid
       */
      Grid.create = function(options) {
          var defaults = {
              controller: Grid,
              detector: Detector.collisions,
              buckets: {},
              pairs: {},
              pairsList: [],
              bucketWidth: 48,
              bucketHeight: 48
          };
  
          return Common.extend(defaults, options);
      };
  
      /**
       * Updates the grid.
       * @method update
       * @param {grid} grid
       * @param {body[]} bodies
       * @param {engine} engine
       * @param {boolean} forceUpdate
       */
      Grid.update = function(grid, bodies, engine, forceUpdate) {
          var i, col, row,
              world = engine.world,
              buckets = grid.buckets,
              bucket,
              bucketId,
              gridChanged = false;
  
  
          for (i = 0; i < bodies.length; i++) {
              var body = bodies[i];
  
              if (body.isSleeping && !forceUpdate)
                  continue;
  
              // don't update out of world bodies
              if (body.bounds.max.x < 0 || body.bounds.min.x > world.bounds.width
                  || body.bounds.max.y < 0 || body.bounds.min.y > world.bounds.height)
                  continue;
  
              var newRegion = _getRegion(grid, body);
  
              // if the body has changed grid region
              if (!body.region || newRegion.id !== body.region.id || forceUpdate) {
  
  
                  if (!body.region || forceUpdate)
                      body.region = newRegion;
  
                  var union = _regionUnion(newRegion, body.region);
  
                  // update grid buckets affected by region change
                  // iterate over the union of both regions
                  for (col = union.startCol; col <= union.endCol; col++) {
                      for (row = union.startRow; row <= union.endRow; row++) {
                          bucketId = _getBucketId(col, row);
                          bucket = buckets[bucketId];
  
                          var isInsideNewRegion = (col >= newRegion.startCol && col <= newRegion.endCol
                                                  && row >= newRegion.startRow && row <= newRegion.endRow);
  
                          var isInsideOldRegion = (col >= body.region.startCol && col <= body.region.endCol
                                                  && row >= body.region.startRow && row <= body.region.endRow);
  
                          // remove from old region buckets
                          if (!isInsideNewRegion && isInsideOldRegion) {
                              if (isInsideOldRegion) {
                                  if (bucket)
                                      _bucketRemoveBody(grid, bucket, body);
                              }
                          }
  
                          // add to new region buckets
                          if (body.region === newRegion || (isInsideNewRegion && !isInsideOldRegion) || forceUpdate) {
                              if (!bucket)
                                  bucket = _createBucket(buckets, bucketId);
                              _bucketAddBody(grid, bucket, body);
                          }
                      }
                  }
  
                  // set the new region
                  body.region = newRegion;
  
                  // flag changes so we can update pairs
                  gridChanged = true;
              }
          }
  
          // update pairs list only if pairs changed (i.e. a body changed region)
          if (gridChanged)
              grid.pairsList = _createActivePairsList(grid);
      };
  
      /**
       * Clears the grid.
       * @method clear
       * @param {grid} grid
       */
      Grid.clear = function(grid) {
          grid.buckets = {};
          grid.pairs = {};
          grid.pairsList = [];
      };
  
      /**
       * Finds the union of two regions.
       * @method _regionUnion
       * @private
       * @param {} regionA
       * @param {} regionB
       * @return {} region
       */
      var _regionUnion = function(regionA, regionB) {
          var startCol = Math.min(regionA.startCol, regionB.startCol),
              endCol = Math.max(regionA.endCol, regionB.endCol),
              startRow = Math.min(regionA.startRow, regionB.startRow),
              endRow = Math.max(regionA.endRow, regionB.endRow);
  
          return _createRegion(startCol, endCol, startRow, endRow);
      };
  
      /**
       * Gets the region a given body falls in for a given grid.
       * @method _getRegion
       * @private
       * @param {} grid
       * @param {} body
       * @return {} region
       */
      var _getRegion = function(grid, body) {
          var bounds = body.bounds,
              startCol = Math.floor(bounds.min.x / grid.bucketWidth),
              endCol = Math.floor(bounds.max.x / grid.bucketWidth),
              startRow = Math.floor(bounds.min.y / grid.bucketHeight),
              endRow = Math.floor(bounds.max.y / grid.bucketHeight);
  
          return _createRegion(startCol, endCol, startRow, endRow);
      };
  
      /**
       * Creates a region.
       * @method _createRegion
       * @private
       * @param {} startCol
       * @param {} endCol
       * @param {} startRow
       * @param {} endRow
       * @return {} region
       */
      var _createRegion = function(startCol, endCol, startRow, endRow) {
          return { 
              id: startCol + ',' + endCol + ',' + startRow + ',' + endRow,
              startCol: startCol, 
              endCol: endCol, 
              startRow: startRow, 
              endRow: endRow 
          };
      };
  
      /**
       * Gets the bucket id at the given position.
       * @method _getBucketId
       * @private
       * @param {} column
       * @param {} row
       * @return {string} bucket id
       */
      var _getBucketId = function(column, row) {
          return column + ',' + row;
      };
  
      /**
       * Creates a bucket.
       * @method _createBucket
       * @private
       * @param {} buckets
       * @param {} bucketId
       * @return {} bucket
       */
      var _createBucket = function(buckets, bucketId) {
          var bucket = buckets[bucketId] = [];
          return bucket;
      };
  
      /**
       * Adds a body to a bucket.
       * @method _bucketAddBody
       * @private
       * @param {} grid
       * @param {} bucket
       * @param {} body
       */
      var _bucketAddBody = function(grid, bucket, body) {
          // add new pairs
          for (var i = 0; i < bucket.length; i++) {
              var bodyB = bucket[i];
  
              if (body.id === bodyB.id || (body.isStatic && bodyB.isStatic))
                  continue;
  
              // keep track of the number of buckets the pair exists in
              // important for Grid.update to work
              var pairId = Pair.id(body, bodyB),
                  pair = grid.pairs[pairId];
  
              if (pair) {
                  pair[2] += 1;
              } else {
                  grid.pairs[pairId] = [body, bodyB, 1];
              }
          }
  
          // add to bodies (after pairs, otherwise pairs with self)
          bucket.push(body);
      };
  
      /**
       * Removes a body from a bucket.
       * @method _bucketRemoveBody
       * @private
       * @param {} grid
       * @param {} bucket
       * @param {} body
       */
      var _bucketRemoveBody = function(grid, bucket, body) {
          // remove from bucket
          bucket.splice(Common.indexOf(bucket, body), 1);
  
          // update pair counts
          for (var i = 0; i < bucket.length; i++) {
              // keep track of the number of buckets the pair exists in
              // important for _createActivePairsList to work
              var bodyB = bucket[i],
                  pairId = Pair.id(body, bodyB),
                  pair = grid.pairs[pairId];
  
              if (pair)
                  pair[2] -= 1;
          }
      };
  
      /**
       * Generates a list of the active pairs in the grid.
       * @method _createActivePairsList
       * @private
       * @param {} grid
       * @return [] pairs
       */
      var _createActivePairsList = function(grid) {
          var pairKeys,
              pair,
              pairs = [];
  
          // grid.pairs is used as a hashmap
          pairKeys = Common.keys(grid.pairs);
  
          // iterate over grid.pairs
          for (var k = 0; k < pairKeys.length; k++) {
              pair = grid.pairs[pairKeys[k]];
  
              // if pair exists in at least one bucket
              // it is a pair that needs further collision testing so push it
              if (pair[2] > 0) {
                  pairs.push(pair);
              } else {
                  delete grid.pairs[pairKeys[k]];
              }
          }
  
          return pairs;
      };
      
  })();
  
  },{"../core/Common":14,"./Detector":5,"./Pair":7}],7:[function(require,module,exports){
  /**
  * The `Matter.Pair` module contains methods for creating and manipulating collision pairs.
  *
  * @class Pair
  */
  
  var Pair = {};
  
  module.exports = Pair;
  
  var Contact = require('./Contact');
  
  (function() {
      
      /**
       * Creates a pair.
       * @method create
       * @param {collision} collision
       * @param {number} timestamp
       * @return {pair} A new pair
       */
      Pair.create = function(collision, timestamp) {
          var bodyA = collision.bodyA,
              bodyB = collision.bodyB,
              parentA = collision.parentA,
              parentB = collision.parentB;
  
          var pair = {
              id: Pair.id(bodyA, bodyB),
              bodyA: bodyA,
              bodyB: bodyB,
              contacts: {},
              activeContacts: [],
              separation: 0,
              isActive: true,
              timeCreated: timestamp,
              timeUpdated: timestamp,
              inverseMass: parentA.inverseMass + parentB.inverseMass,
              friction: Math.min(parentA.friction, parentB.friction),
              frictionStatic: Math.max(parentA.frictionStatic, parentB.frictionStatic),
              restitution: Math.max(parentA.restitution, parentB.restitution),
              slop: Math.max(parentA.slop, parentB.slop)
          };
  
          Pair.update(pair, collision, timestamp);
  
          return pair;
      };
  
      /**
       * Updates a pair given a collision.
       * @method update
       * @param {pair} pair
       * @param {collision} collision
       * @param {number} timestamp
       */
      Pair.update = function(pair, collision, timestamp) {
          var contacts = pair.contacts,
              supports = collision.supports,
              activeContacts = pair.activeContacts,
              parentA = collision.parentA,
              parentB = collision.parentB;
          
          pair.collision = collision;
          pair.inverseMass = parentA.inverseMass + parentB.inverseMass;
          pair.friction = Math.min(parentA.friction, parentB.friction);
          pair.frictionStatic = Math.max(parentA.frictionStatic, parentB.frictionStatic);
          pair.restitution = Math.max(parentA.restitution, parentB.restitution);
          pair.slop = Math.max(parentA.slop, parentB.slop);
          activeContacts.length = 0;
          
          if (collision.collided) {
              for (var i = 0; i < supports.length; i++) {
                  var support = supports[i],
                      contactId = Contact.id(support),
                      contact = contacts[contactId];
  
                  if (contact) {
                      activeContacts.push(contact);
                  } else {
                      activeContacts.push(contacts[contactId] = Contact.create(support));
                  }
              }
  
              pair.separation = collision.depth;
              Pair.setActive(pair, true, timestamp);
          } else {
              if (pair.isActive === true)
                  Pair.setActive(pair, false, timestamp);
          }
      };
      
      /**
       * Set a pair as active or inactive.
       * @method setActive
       * @param {pair} pair
       * @param {bool} isActive
       * @param {number} timestamp
       */
      Pair.setActive = function(pair, isActive, timestamp) {
          if (isActive) {
              pair.isActive = true;
              pair.timeUpdated = timestamp;
          } else {
              pair.isActive = false;
              pair.activeContacts.length = 0;
          }
      };
  
      /**
       * Get the id for the given pair.
       * @method id
       * @param {body} bodyA
       * @param {body} bodyB
       * @return {string} Unique pairId
       */
      Pair.id = function(bodyA, bodyB) {
          if (bodyA.id < bodyB.id) {
              return bodyA.id + '_' + bodyB.id;
          } else {
              return bodyB.id + '_' + bodyA.id;
          }
      };
  
  })();
  
  },{"./Contact":4}],8:[function(require,module,exports){
  /**
  * The `Matter.Pairs` module contains methods for creating and manipulating collision pair sets.
  *
  * @class Pairs
  */
  
  var Pairs = {};
  
  module.exports = Pairs;
  
  var Pair = require('./Pair');
  var Common = require('../core/Common');
  
  (function() {
      
      var _pairMaxIdleLife = 1000;
  
      /**
       * Creates a new pairs structure.
       * @method create
       * @param {object} options
       * @return {pairs} A new pairs structure
       */
      Pairs.create = function(options) {
          return Common.extend({ 
              table: {},
              list: [],
              collisionStart: [],
              collisionActive: [],
              collisionEnd: []
          }, options);
      };
  
      /**
       * Updates pairs given a list of collisions.
       * @method update
       * @param {object} pairs
       * @param {collision[]} collisions
       * @param {number} timestamp
       */
      Pairs.update = function(pairs, collisions, timestamp) {
          var pairsList = pairs.list,
              pairsTable = pairs.table,
              collisionStart = pairs.collisionStart,
              collisionEnd = pairs.collisionEnd,
              collisionActive = pairs.collisionActive,
              activePairIds = [],
              collision,
              pairId,
              pair,
              i;
  
          // clear collision state arrays, but maintain old reference
          collisionStart.length = 0;
          collisionEnd.length = 0;
          collisionActive.length = 0;
  
          for (i = 0; i < collisions.length; i++) {
              collision = collisions[i];
  
              if (collision.collided) {
                  pairId = Pair.id(collision.bodyA, collision.bodyB);
                  activePairIds.push(pairId);
  
                  pair = pairsTable[pairId];
                  
                  if (pair) {
                      // pair already exists (but may or may not be active)
                      if (pair.isActive) {
                          // pair exists and is active
                          collisionActive.push(pair);
                      } else {
                          // pair exists but was inactive, so a collision has just started again
                          collisionStart.push(pair);
                      }
  
                      // update the pair
                      Pair.update(pair, collision, timestamp);
                  } else {
                      // pair did not exist, create a new pair
                      pair = Pair.create(collision, timestamp);
                      pairsTable[pairId] = pair;
  
                      // push the new pair
                      collisionStart.push(pair);
                      pairsList.push(pair);
                  }
              }
          }
  
          // deactivate previously active pairs that are now inactive
          for (i = 0; i < pairsList.length; i++) {
              pair = pairsList[i];
              if (pair.isActive && Common.indexOf(activePairIds, pair.id) === -1) {
                  Pair.setActive(pair, false, timestamp);
                  collisionEnd.push(pair);
              }
          }
      };
      
      /**
       * Finds and removes pairs that have been inactive for a set amount of time.
       * @method removeOld
       * @param {object} pairs
       * @param {number} timestamp
       */
      Pairs.removeOld = function(pairs, timestamp) {
          var pairsList = pairs.list,
              pairsTable = pairs.table,
              indexesToRemove = [],
              pair,
              collision,
              pairIndex,
              i;
  
          for (i = 0; i < pairsList.length; i++) {
              pair = pairsList[i];
              collision = pair.collision;
              
              // never remove sleeping pairs
              if (collision.bodyA.isSleeping || collision.bodyB.isSleeping) {
                  pair.timeUpdated = timestamp;
                  continue;
              }
  
              // if pair is inactive for too long, mark it to be removed
              if (timestamp - pair.timeUpdated > _pairMaxIdleLife) {
                  indexesToRemove.push(i);
              }
          }
  
          // remove marked pairs
          for (i = 0; i < indexesToRemove.length; i++) {
              pairIndex = indexesToRemove[i] - i;
              pair = pairsList[pairIndex];
              delete pairsTable[pair.id];
              pairsList.splice(pairIndex, 1);
          }
      };
  
      /**
       * Clears the given pairs structure.
       * @method clear
       * @param {pairs} pairs
       * @return {pairs} pairs
       */
      Pairs.clear = function(pairs) {
          pairs.table = {};
          pairs.list.length = 0;
          pairs.collisionStart.length = 0;
          pairs.collisionActive.length = 0;
          pairs.collisionEnd.length = 0;
          return pairs;
      };
  
  })();
  
  },{"../core/Common":14,"./Pair":7}],9:[function(require,module,exports){
  /**
  * The `Matter.Query` module contains methods for performing collision queries.
  *
  * See the included usage [examples](https://github.com/liabru/matter-js/tree/master/examples).
  *
  * @class Query
  */
  
  var Query = {};
  
  module.exports = Query;
  
  var Vector = require('../geometry/Vector');
  var SAT = require('./SAT');
  var Bounds = require('../geometry/Bounds');
  var Bodies = require('../factory/Bodies');
  var Vertices = require('../geometry/Vertices');
  
  (function() {
  
      /**
       * Casts a ray segment against a set of bodies and returns all collisions, ray width is optional. Intersection points are not provided.
       * @method ray
       * @param {body[]} bodies
       * @param {vector} startPoint
       * @param {vector} endPoint
       * @param {number} [rayWidth]
       * @return {object[]} Collisions
       */
      Query.ray = function(bodies, startPoint, endPoint, rayWidth) {
          rayWidth = rayWidth || 1e-100;
  
          var rayAngle = Vector.angle(startPoint, endPoint),
              rayLength = Vector.magnitude(Vector.sub(startPoint, endPoint)),
              rayX = (endPoint.x + startPoint.x) * 0.5,
              rayY = (endPoint.y + startPoint.y) * 0.5,
              ray = Bodies.rectangle(rayX, rayY, rayLength, rayWidth, { angle: rayAngle }),
              collisions = [];
  
          for (var i = 0; i < bodies.length; i++) {
              var bodyA = bodies[i];
              
              if (Bounds.overlaps(bodyA.bounds, ray.bounds)) {
                  for (var j = bodyA.parts.length === 1 ? 0 : 1; j < bodyA.parts.length; j++) {
                      var part = bodyA.parts[j];
  
                      if (Bounds.overlaps(part.bounds, ray.bounds)) {
                          var collision = SAT.collides(part, ray);
                          if (collision.collided) {
                              collision.body = collision.bodyA = collision.bodyB = bodyA;
                              collisions.push(collision);
                              break;
                          }
                      }
                  }
              }
          }
  
          return collisions;
      };
  
      /**
       * Returns all bodies whose bounds are inside (or outside if set) the given set of bounds, from the given set of bodies.
       * @method region
       * @param {body[]} bodies
       * @param {bounds} bounds
       * @param {bool} [outside=false]
       * @return {body[]} The bodies matching the query
       */
      Query.region = function(bodies, bounds, outside) {
          var result = [];
  
          for (var i = 0; i < bodies.length; i++) {
              var body = bodies[i],
                  overlaps = Bounds.overlaps(body.bounds, bounds);
              if ((overlaps && !outside) || (!overlaps && outside))
                  result.push(body);
          }
  
          return result;
      };
  
      /**
       * Returns all bodies whose vertices contain the given point, from the given set of bodies.
       * @method point
       * @param {body[]} bodies
       * @param {vector} point
       * @return {body[]} The bodies matching the query
       */
      Query.point = function(bodies, point) {
          var result = [];
  
          for (var i = 0; i < bodies.length; i++) {
              var body = bodies[i];
              
              if (Bounds.contains(body.bounds, point)) {
                  for (var j = body.parts.length === 1 ? 0 : 1; j < body.parts.length; j++) {
                      var part = body.parts[j];
  
                      if (Bounds.contains(part.bounds, point)
                          && Vertices.contains(part.vertices, point)) {
                          result.push(body);
                          break;
                      }
                  }
              }
          }
  
          return result;
      };
  
  })();
  
  },{"../factory/Bodies":21,"../geometry/Bounds":24,"../geometry/Vector":26,"../geometry/Vertices":27,"./SAT":11}],10:[function(require,module,exports){
  /**
  * The `Matter.Resolver` module contains methods for resolving collision pairs.
  *
  * @class Resolver
  */
  
  var Resolver = {};
  
  module.exports = Resolver;
  
  var Vertices = require('../geometry/Vertices');
  var Vector = require('../geometry/Vector');
  var Common = require('../core/Common');
  var Bounds = require('../geometry/Bounds');
  
  (function() {
  
      Resolver._restingThresh = 4;
      Resolver._restingThreshTangent = 6;
      Resolver._positionDampen = 0.9;
      Resolver._positionWarming = 0.8;
      Resolver._frictionNormalMultiplier = 5;
  
      /**
       * Prepare pairs for position solving.
       * @method preSolvePosition
       * @param {pair[]} pairs
       */
      Resolver.preSolvePosition = function(pairs) {
          var i,
              pair,
              activeCount;
  
          // find total contacts on each body
          for (i = 0; i < pairs.length; i++) {
              pair = pairs[i];
              
              if (!pair.isActive)
                  continue;
              
              activeCount = pair.activeContacts.length;
              pair.collision.parentA.totalContacts += activeCount;
              pair.collision.parentB.totalContacts += activeCount;
          }
      };
  
      /**
       * Find a solution for pair positions.
       * @method solvePosition
       * @param {pair[]} pairs
       * @param {number} timeScale
       */
      Resolver.solvePosition = function(pairs, timeScale) {
          var i,
              pair,
              collision,
              bodyA,
              bodyB,
              normal,
              bodyBtoA,
              contactShare,
              positionImpulse,
              contactCount = {},
              tempA = Vector._temp[0],
              tempB = Vector._temp[1],
              tempC = Vector._temp[2],
              tempD = Vector._temp[3];
  
          // find impulses required to resolve penetration
          for (i = 0; i < pairs.length; i++) {
              pair = pairs[i];
              
              if (!pair.isActive)
                  continue;
              
              collision = pair.collision;
              bodyA = collision.parentA;
              bodyB = collision.parentB;
              normal = collision.normal;
  
              // get current separation between body edges involved in collision
              bodyBtoA = Vector.sub(Vector.add(bodyB.positionImpulse, bodyB.position, tempA), 
                                      Vector.add(bodyA.positionImpulse, 
                                          Vector.sub(bodyB.position, collision.penetration, tempB), tempC), tempD);
  
              pair.separation = Vector.dot(normal, bodyBtoA);
          }
          
          for (i = 0; i < pairs.length; i++) {
              pair = pairs[i];
  
              if (!pair.isActive || pair.separation < 0)
                  continue;
              
              collision = pair.collision;
              bodyA = collision.parentA;
              bodyB = collision.parentB;
              normal = collision.normal;
              positionImpulse = (pair.separation - pair.slop) * timeScale;
          
              if (bodyA.isStatic || bodyB.isStatic)
                  positionImpulse *= 2;
              
              if (!(bodyA.isStatic || bodyA.isSleeping)) {
                  contactShare = Resolver._positionDampen / bodyA.totalContacts;
                  bodyA.positionImpulse.x += normal.x * positionImpulse * contactShare;
                  bodyA.positionImpulse.y += normal.y * positionImpulse * contactShare;
              }
  
              if (!(bodyB.isStatic || bodyB.isSleeping)) {
                  contactShare = Resolver._positionDampen / bodyB.totalContacts;
                  bodyB.positionImpulse.x -= normal.x * positionImpulse * contactShare;
                  bodyB.positionImpulse.y -= normal.y * positionImpulse * contactShare;
              }
          }
      };
  
      /**
       * Apply position resolution.
       * @method postSolvePosition
       * @param {body[]} bodies
       */
      Resolver.postSolvePosition = function(bodies) {
          for (var i = 0; i < bodies.length; i++) {
              var body = bodies[i];
  
              // reset contact count
              body.totalContacts = 0;
  
              if (body.positionImpulse.x !== 0 || body.positionImpulse.y !== 0) {
                  // update body geometry
                  for (var j = 0; j < body.parts.length; j++) {
                      var part = body.parts[j];
                      Vertices.translate(part.vertices, body.positionImpulse);
                      Bounds.update(part.bounds, part.vertices, body.velocity);
                      part.position.x += body.positionImpulse.x;
                      part.position.y += body.positionImpulse.y;
                  }
  
                  // move the body without changing velocity
                  body.positionPrev.x += body.positionImpulse.x;
                  body.positionPrev.y += body.positionImpulse.y;
  
                  if (Vector.dot(body.positionImpulse, body.velocity) < 0) {
                      // reset cached impulse if the body has velocity along it
                      body.positionImpulse.x = 0;
                      body.positionImpulse.y = 0;
                  } else {
                      // warm the next iteration
                      body.positionImpulse.x *= Resolver._positionWarming;
                      body.positionImpulse.y *= Resolver._positionWarming;
                  }
              }
          }
      };
  
      /**
       * Prepare pairs for velocity solving.
       * @method preSolveVelocity
       * @param {pair[]} pairs
       */
      Resolver.preSolveVelocity = function(pairs) {
          var i,
              j,
              pair,
              contacts,
              collision,
              bodyA,
              bodyB,
              normal,
              tangent,
              contact,
              contactVertex,
              normalImpulse,
              tangentImpulse,
              offset,
              impulse = Vector._temp[0],
              tempA = Vector._temp[1];
          
          for (i = 0; i < pairs.length; i++) {
              pair = pairs[i];
              
              if (!pair.isActive)
                  continue;
              
              contacts = pair.activeContacts;
              collision = pair.collision;
              bodyA = collision.parentA;
              bodyB = collision.parentB;
              normal = collision.normal;
              tangent = collision.tangent;
                  
              // resolve each contact
              for (j = 0; j < contacts.length; j++) {
                  contact = contacts[j];
                  contactVertex = contact.vertex;
                  normalImpulse = contact.normalImpulse;
                  tangentImpulse = contact.tangentImpulse;
  
                  if (normalImpulse !== 0 || tangentImpulse !== 0) {
                      // total impulse from contact
                      impulse.x = (normal.x * normalImpulse) + (tangent.x * tangentImpulse);
                      impulse.y = (normal.y * normalImpulse) + (tangent.y * tangentImpulse);
                      
                      // apply impulse from contact
                      if (!(bodyA.isStatic || bodyA.isSleeping)) {
                          offset = Vector.sub(contactVertex, bodyA.position, tempA);
                          bodyA.positionPrev.x += impulse.x * bodyA.inverseMass;
                          bodyA.positionPrev.y += impulse.y * bodyA.inverseMass;
                          bodyA.anglePrev += Vector.cross(offset, impulse) * bodyA.inverseInertia;
                      }
  
                      if (!(bodyB.isStatic || bodyB.isSleeping)) {
                          offset = Vector.sub(contactVertex, bodyB.position, tempA);
                          bodyB.positionPrev.x -= impulse.x * bodyB.inverseMass;
                          bodyB.positionPrev.y -= impulse.y * bodyB.inverseMass;
                          bodyB.anglePrev -= Vector.cross(offset, impulse) * bodyB.inverseInertia;
                      }
                  }
              }
          }
      };
  
      /**
       * Find a solution for pair velocities.
       * @method solveVelocity
       * @param {pair[]} pairs
       * @param {number} timeScale
       */
      Resolver.solveVelocity = function(pairs, timeScale) {
          var timeScaleSquared = timeScale * timeScale,
              impulse = Vector._temp[0],
              tempA = Vector._temp[1],
              tempB = Vector._temp[2],
              tempC = Vector._temp[3],
              tempD = Vector._temp[4],
              tempE = Vector._temp[5];
          
          for (var i = 0; i < pairs.length; i++) {
              var pair = pairs[i];
              
              if (!pair.isActive)
                  continue;
              
              var collision = pair.collision,
                  bodyA = collision.parentA,
                  bodyB = collision.parentB,
                  normal = collision.normal,
                  tangent = collision.tangent,
                  contacts = pair.activeContacts,
                  contactShare = 1 / contacts.length;
  
              // update body velocities
              bodyA.velocity.x = bodyA.position.x - bodyA.positionPrev.x;
              bodyA.velocity.y = bodyA.position.y - bodyA.positionPrev.y;
              bodyB.velocity.x = bodyB.position.x - bodyB.positionPrev.x;
              bodyB.velocity.y = bodyB.position.y - bodyB.positionPrev.y;
              bodyA.angularVelocity = bodyA.angle - bodyA.anglePrev;
              bodyB.angularVelocity = bodyB.angle - bodyB.anglePrev;
  
              // resolve each contact
              for (var j = 0; j < contacts.length; j++) {
                  var contact = contacts[j],
                      contactVertex = contact.vertex,
                      offsetA = Vector.sub(contactVertex, bodyA.position, tempA),
                      offsetB = Vector.sub(contactVertex, bodyB.position, tempB),
                      velocityPointA = Vector.add(bodyA.velocity, Vector.mult(Vector.perp(offsetA), bodyA.angularVelocity), tempC),
                      velocityPointB = Vector.add(bodyB.velocity, Vector.mult(Vector.perp(offsetB), bodyB.angularVelocity), tempD), 
                      relativeVelocity = Vector.sub(velocityPointA, velocityPointB, tempE),
                      normalVelocity = Vector.dot(normal, relativeVelocity);
  
                  var tangentVelocity = Vector.dot(tangent, relativeVelocity),
                      tangentSpeed = Math.abs(tangentVelocity),
                      tangentVelocityDirection = Common.sign(tangentVelocity);
  
                  // raw impulses
                  var normalImpulse = (1 + pair.restitution) * normalVelocity,
                      normalForce = Common.clamp(pair.separation + normalVelocity, 0, 1) * Resolver._frictionNormalMultiplier;
  
                  // coulomb friction
                  var tangentImpulse = tangentVelocity,
                      maxFriction = Infinity;
  
                  if (tangentSpeed > pair.friction * pair.frictionStatic * normalForce * timeScaleSquared) {
                      maxFriction = tangentSpeed;
                      tangentImpulse = Common.clamp(
                          pair.friction * tangentVelocityDirection * timeScaleSquared,
                          -maxFriction, maxFriction
                      );
                  }
  
                  // modify impulses accounting for mass, inertia and offset
                  var oAcN = Vector.cross(offsetA, normal),
                      oBcN = Vector.cross(offsetB, normal),
                      share = contactShare / (bodyA.inverseMass + bodyB.inverseMass + bodyA.inverseInertia * oAcN * oAcN  + bodyB.inverseInertia * oBcN * oBcN);
  
                  normalImpulse *= share;
                  tangentImpulse *= share;
  
                  // handle high velocity and resting collisions separately
                  if (normalVelocity < 0 && normalVelocity * normalVelocity > Resolver._restingThresh * timeScaleSquared) {
                      // high normal velocity so clear cached contact normal impulse
                      contact.normalImpulse = 0;
                  } else {
                      // solve resting collision constraints using Erin Catto's method (GDC08)
                      // impulse constraint tends to 0
                      var contactNormalImpulse = contact.normalImpulse;
                      contact.normalImpulse = Math.min(contact.normalImpulse + normalImpulse, 0);
                      normalImpulse = contact.normalImpulse - contactNormalImpulse;
                  }
  
                  // handle high velocity and resting collisions separately
                  if (tangentVelocity * tangentVelocity > Resolver._restingThreshTangent * timeScaleSquared) {
                      // high tangent velocity so clear cached contact tangent impulse
                      contact.tangentImpulse = 0;
                  } else {
                      // solve resting collision constraints using Erin Catto's method (GDC08)
                      // tangent impulse tends to -tangentSpeed or +tangentSpeed
                      var contactTangentImpulse = contact.tangentImpulse;
                      contact.tangentImpulse = Common.clamp(contact.tangentImpulse + tangentImpulse, -maxFriction, maxFriction);
                      tangentImpulse = contact.tangentImpulse - contactTangentImpulse;
                  }
  
                  // total impulse from contact
                  impulse.x = (normal.x * normalImpulse) + (tangent.x * tangentImpulse);
                  impulse.y = (normal.y * normalImpulse) + (tangent.y * tangentImpulse);
                  
                  // apply impulse from contact
                  if (!(bodyA.isStatic || bodyA.isSleeping)) {
                      bodyA.positionPrev.x += impulse.x * bodyA.inverseMass;
                      bodyA.positionPrev.y += impulse.y * bodyA.inverseMass;
                      bodyA.anglePrev += Vector.cross(offsetA, impulse) * bodyA.inverseInertia;
                  }
  
                  if (!(bodyB.isStatic || bodyB.isSleeping)) {
                      bodyB.positionPrev.x -= impulse.x * bodyB.inverseMass;
                      bodyB.positionPrev.y -= impulse.y * bodyB.inverseMass;
                      bodyB.anglePrev -= Vector.cross(offsetB, impulse) * bodyB.inverseInertia;
                  }
              }
          }
      };
  
  })();
  
  },{"../core/Common":14,"../geometry/Bounds":24,"../geometry/Vector":26,"../geometry/Vertices":27}],11:[function(require,module,exports){
  /**
  * The `Matter.SAT` module contains methods for detecting collisions using the Separating Axis Theorem.
  *
  * @class SAT
  */
  
  // TODO: true circles and curves
  
  var SAT = {};
  
  module.exports = SAT;
  
  var Vertices = require('../geometry/Vertices');
  var Vector = require('../geometry/Vector');
  
  (function() {
  
      /**
       * Detect collision between two bodies using the Separating Axis Theorem.
       * @method collides
       * @param {body} bodyA
       * @param {body} bodyB
       * @param {collision} previousCollision
       * @return {collision} collision
       */
      SAT.collides = function(bodyA, bodyB, previousCollision) {
          var overlapAB,
              overlapBA, 
              minOverlap,
              collision,
              prevCol = previousCollision,
              canReusePrevCol = false;
  
          if (prevCol) {
              // estimate total motion
              var parentA = bodyA.parent,
                  parentB = bodyB.parent,
                  motion = parentA.speed * parentA.speed + parentA.angularSpeed * parentA.angularSpeed
                         + parentB.speed * parentB.speed + parentB.angularSpeed * parentB.angularSpeed;
  
              // we may be able to (partially) reuse collision result 
              // but only safe if collision was resting
              canReusePrevCol = prevCol && prevCol.collided && motion < 0.2;
  
              // reuse collision object
              collision = prevCol;
          } else {
              collision = { collided: false, bodyA: bodyA, bodyB: bodyB };
          }
  
          if (prevCol && canReusePrevCol) {
              // if we can reuse the collision result
              // we only need to test the previously found axis
              var axisBodyA = collision.axisBody,
                  axisBodyB = axisBodyA === bodyA ? bodyB : bodyA,
                  axes = [axisBodyA.axes[prevCol.axisNumber]];
  
              minOverlap = _overlapAxes(axisBodyA.vertices, axisBodyB.vertices, axes);
              collision.reused = true;
  
              if (minOverlap.overlap <= 0) {
                  collision.collided = false;
                  return collision;
              }
          } else {
              // if we can't reuse a result, perform a full SAT test
  
              overlapAB = _overlapAxes(bodyA.vertices, bodyB.vertices, bodyA.axes);
  
              if (overlapAB.overlap <= 0) {
                  collision.collided = false;
                  return collision;
              }
  
              overlapBA = _overlapAxes(bodyB.vertices, bodyA.vertices, bodyB.axes);
  
              if (overlapBA.overlap <= 0) {
                  collision.collided = false;
                  return collision;
              }
  
              if (overlapAB.overlap < overlapBA.overlap) {
                  minOverlap = overlapAB;
                  collision.axisBody = bodyA;
              } else {
                  minOverlap = overlapBA;
                  collision.axisBody = bodyB;
              }
  
              // important for reuse later
              collision.axisNumber = minOverlap.axisNumber;
          }
  
          collision.bodyA = bodyA.id < bodyB.id ? bodyA : bodyB;
          collision.bodyB = bodyA.id < bodyB.id ? bodyB : bodyA;
          collision.collided = true;
          collision.normal = minOverlap.axis;
          collision.depth = minOverlap.overlap;
          collision.parentA = collision.bodyA.parent;
          collision.parentB = collision.bodyB.parent;
          
          bodyA = collision.bodyA;
          bodyB = collision.bodyB;
  
          // ensure normal is facing away from bodyA
          if (Vector.dot(collision.normal, Vector.sub(bodyB.position, bodyA.position)) > 0) 
              collision.normal = Vector.neg(collision.normal);
  
          collision.tangent = Vector.perp(collision.normal);
  
          collision.penetration = { 
              x: collision.normal.x * collision.depth, 
              y: collision.normal.y * collision.depth 
          };
  
          // find support points, there is always either exactly one or two
          var verticesB = _findSupports(bodyA, bodyB, collision.normal),
              supports = collision.supports || [];
          supports.length = 0;
  
          // find the supports from bodyB that are inside bodyA
          if (Vertices.contains(bodyA.vertices, verticesB[0]))
              supports.push(verticesB[0]);
  
          if (Vertices.contains(bodyA.vertices, verticesB[1]))
              supports.push(verticesB[1]);
  
          // find the supports from bodyA that are inside bodyB
          if (supports.length < 2) {
              var verticesA = _findSupports(bodyB, bodyA, Vector.neg(collision.normal));
                  
              if (Vertices.contains(bodyB.vertices, verticesA[0]))
                  supports.push(verticesA[0]);
  
              if (supports.length < 2 && Vertices.contains(bodyB.vertices, verticesA[1]))
                  supports.push(verticesA[1]);
          }
  
          // account for the edge case of overlapping but no vertex containment
          if (supports.length < 1)
              supports = [verticesB[0]];
          
          collision.supports = supports;
  
          return collision;
      };
  
      /**
       * Find the overlap between two sets of vertices.
       * @method _overlapAxes
       * @private
       * @param {} verticesA
       * @param {} verticesB
       * @param {} axes
       * @return result
       */
      var _overlapAxes = function(verticesA, verticesB, axes) {
          var projectionA = Vector._temp[0], 
              projectionB = Vector._temp[1],
              result = { overlap: Number.MAX_VALUE },
              overlap,
              axis;
  
          for (var i = 0; i < axes.length; i++) {
              axis = axes[i];
  
              _projectToAxis(projectionA, verticesA, axis);
              _projectToAxis(projectionB, verticesB, axis);
  
              overlap = Math.min(projectionA.max - projectionB.min, projectionB.max - projectionA.min);
  
              if (overlap <= 0) {
                  result.overlap = overlap;
                  return result;
              }
  
              if (overlap < result.overlap) {
                  result.overlap = overlap;
                  result.axis = axis;
                  result.axisNumber = i;
              }
          }
  
          return result;
      };
  
      /**
       * Projects vertices on an axis and returns an interval.
       * @method _projectToAxis
       * @private
       * @param {} projection
       * @param {} vertices
       * @param {} axis
       */
      var _projectToAxis = function(projection, vertices, axis) {
          var min = Vector.dot(vertices[0], axis),
              max = min;
  
          for (var i = 1; i < vertices.length; i += 1) {
              var dot = Vector.dot(vertices[i], axis);
  
              if (dot > max) { 
                  max = dot; 
              } else if (dot < min) { 
                  min = dot; 
              }
          }
  
          projection.min = min;
          projection.max = max;
      };
      
      /**
       * Finds supporting vertices given two bodies along a given direction using hill-climbing.
       * @method _findSupports
       * @private
       * @param {} bodyA
       * @param {} bodyB
       * @param {} normal
       * @return [vector]
       */
      var _findSupports = function(bodyA, bodyB, normal) {
          var nearestDistance = Number.MAX_VALUE,
              vertexToBody = Vector._temp[0],
              vertices = bodyB.vertices,
              bodyAPosition = bodyA.position,
              distance,
              vertex,
              vertexA,
              vertexB;
  
          // find closest vertex on bodyB
          for (var i = 0; i < vertices.length; i++) {
              vertex = vertices[i];
              vertexToBody.x = vertex.x - bodyAPosition.x;
              vertexToBody.y = vertex.y - bodyAPosition.y;
              distance = -Vector.dot(normal, vertexToBody);
  
              if (distance < nearestDistance) {
                  nearestDistance = distance;
                  vertexA = vertex;
              }
          }
  
          // find next closest vertex using the two connected to it
          var prevIndex = vertexA.index - 1 >= 0 ? vertexA.index - 1 : vertices.length - 1;
          vertex = vertices[prevIndex];
          vertexToBody.x = vertex.x - bodyAPosition.x;
          vertexToBody.y = vertex.y - bodyAPosition.y;
          nearestDistance = -Vector.dot(normal, vertexToBody);
          vertexB = vertex;
  
          var nextIndex = (vertexA.index + 1) % vertices.length;
          vertex = vertices[nextIndex];
          vertexToBody.x = vertex.x - bodyAPosition.x;
          vertexToBody.y = vertex.y - bodyAPosition.y;
          distance = -Vector.dot(normal, vertexToBody);
          if (distance < nearestDistance) {
              vertexB = vertex;
          }
  
          return [vertexA, vertexB];
      };
  
  })();
  
  },{"../geometry/Vector":26,"../geometry/Vertices":27}],12:[function(require,module,exports){
  /**
  * The `Matter.Constraint` module contains methods for creating and manipulating constraints.
  * Constraints are used for specifying that a fixed distance must be maintained between two bodies (or a body and a fixed world-space position).
  * The stiffness of constraints can be modified to create springs or elastic.
  *
  * See the included usage [examples](https://github.com/liabru/matter-js/tree/master/examples).
  *
  * @class Constraint
  */
  
  // TODO: fix instability issues with torque
  // TODO: linked constraints
  // TODO: breakable constraints
  // TODO: collision constraints
  // TODO: allow constrained bodies to sleep
  // TODO: handle 0 length constraints properly
  // TODO: impulse caching and warming
  
  var Constraint = {};
  
  module.exports = Constraint;
  
  var Vertices = require('../geometry/Vertices');
  var Vector = require('../geometry/Vector');
  var Sleeping = require('../core/Sleeping');
  var Bounds = require('../geometry/Bounds');
  var Axes = require('../geometry/Axes');
  var Common = require('../core/Common');
  
  (function() {
  
      var _minLength = 0.000001,
          _minDifference = 0.001;
  
      /**
       * Creates a new constraint.
       * All properties have default values, and many are pre-calculated automatically based on other properties.
       * See the properties section below for detailed information on what you can pass via the `options` object.
       * @method create
       * @param {} options
       * @return {constraint} constraint
       */
      Constraint.create = function(options) {
          var constraint = options;
  
          // if bodies defined but no points, use body centre
          if (constraint.bodyA && !constraint.pointA)
              constraint.pointA = { x: 0, y: 0 };
          if (constraint.bodyB && !constraint.pointB)
              constraint.pointB = { x: 0, y: 0 };
  
          // calculate static length using initial world space points
          var initialPointA = constraint.bodyA ? Vector.add(constraint.bodyA.position, constraint.pointA) : constraint.pointA,
              initialPointB = constraint.bodyB ? Vector.add(constraint.bodyB.position, constraint.pointB) : constraint.pointB,
              length = Vector.magnitude(Vector.sub(initialPointA, initialPointB));
      
          constraint.length = constraint.length || length || _minLength;
  
          // render
          var render = {
              visible: true,
              lineWidth: 2,
              strokeStyle: '#666'
          };
          
          constraint.render = Common.extend(render, constraint.render);
  
          // option defaults
          constraint.id = constraint.id || Common.nextId();
          constraint.label = constraint.label || 'Constraint';
          constraint.type = 'constraint';
          constraint.stiffness = constraint.stiffness || 1;
          constraint.angularStiffness = constraint.angularStiffness || 0;
          constraint.angleA = constraint.bodyA ? constraint.bodyA.angle : constraint.angleA;
          constraint.angleB = constraint.bodyB ? constraint.bodyB.angle : constraint.angleB;
  
          return constraint;
      };
  
      /**
       * Solves all constraints in a list of collisions.
       * @private
       * @method solveAll
       * @param {constraint[]} constraints
       * @param {number} timeScale
       */
      Constraint.solveAll = function(constraints, timeScale) {
          for (var i = 0; i < constraints.length; i++) {
              Constraint.solve(constraints[i], timeScale);
          }
      };
  
      /**
       * Solves a distance constraint with Gauss-Siedel method.
       * @private
       * @method solve
       * @param {constraint} constraint
       * @param {number} timeScale
       */
      Constraint.solve = function(constraint, timeScale) {
          var bodyA = constraint.bodyA,
              bodyB = constraint.bodyB,
              pointA = constraint.pointA,
              pointB = constraint.pointB;
  
          // update reference angle
          if (bodyA && !bodyA.isStatic) {
              constraint.pointA = Vector.rotate(pointA, bodyA.angle - constraint.angleA);
              constraint.angleA = bodyA.angle;
          }
          
          // update reference angle
          if (bodyB && !bodyB.isStatic) {
              constraint.pointB = Vector.rotate(pointB, bodyB.angle - constraint.angleB);
              constraint.angleB = bodyB.angle;
          }
  
          var pointAWorld = pointA,
              pointBWorld = pointB;
  
          if (bodyA) pointAWorld = Vector.add(bodyA.position, pointA);
          if (bodyB) pointBWorld = Vector.add(bodyB.position, pointB);
  
          if (!pointAWorld || !pointBWorld)
              return;
  
          var delta = Vector.sub(pointAWorld, pointBWorld),
              currentLength = Vector.magnitude(delta);
  
          // prevent singularity
          if (currentLength === 0)
              currentLength = _minLength;
  
          // solve distance constraint with Gauss-Siedel method
          var difference = (currentLength - constraint.length) / currentLength,
              normal = Vector.div(delta, currentLength),
              force = Vector.mult(delta, difference * 0.5 * constraint.stiffness * timeScale * timeScale);
          
          // if difference is very small, we can skip
          if (Math.abs(1 - (currentLength / constraint.length)) < _minDifference * timeScale)
              return;
  
          var velocityPointA,
              velocityPointB,
              offsetA,
              offsetB,
              oAn,
              oBn,
              bodyADenom,
              bodyBDenom;
      
          if (bodyA && !bodyA.isStatic) {
              // point body offset
              offsetA = { 
                  x: pointAWorld.x - bodyA.position.x + force.x, 
                  y: pointAWorld.y - bodyA.position.y + force.y
              };
              
              // update velocity
              bodyA.velocity.x = bodyA.position.x - bodyA.positionPrev.x;
              bodyA.velocity.y = bodyA.position.y - bodyA.positionPrev.y;
              bodyA.angularVelocity = bodyA.angle - bodyA.anglePrev;
              
              // find point velocity and body mass
              velocityPointA = Vector.add(bodyA.velocity, Vector.mult(Vector.perp(offsetA), bodyA.angularVelocity));
              oAn = Vector.dot(offsetA, normal);
              bodyADenom = bodyA.inverseMass + bodyA.inverseInertia * oAn * oAn;
          } else {
              velocityPointA = { x: 0, y: 0 };
              bodyADenom = bodyA ? bodyA.inverseMass : 0;
          }
              
          if (bodyB && !bodyB.isStatic) {
              // point body offset
              offsetB = { 
                  x: pointBWorld.x - bodyB.position.x - force.x, 
                  y: pointBWorld.y - bodyB.position.y - force.y 
              };
              
              // update velocity
              bodyB.velocity.x = bodyB.position.x - bodyB.positionPrev.x;
              bodyB.velocity.y = bodyB.position.y - bodyB.positionPrev.y;
              bodyB.angularVelocity = bodyB.angle - bodyB.anglePrev;
  
              // find point velocity and body mass
              velocityPointB = Vector.add(bodyB.velocity, Vector.mult(Vector.perp(offsetB), bodyB.angularVelocity));
              oBn = Vector.dot(offsetB, normal);
              bodyBDenom = bodyB.inverseMass + bodyB.inverseInertia * oBn * oBn;
          } else {
              velocityPointB = { x: 0, y: 0 };
              bodyBDenom = bodyB ? bodyB.inverseMass : 0;
          }
          
          var relativeVelocity = Vector.sub(velocityPointB, velocityPointA),
              normalImpulse = Vector.dot(normal, relativeVelocity) / (bodyADenom + bodyBDenom);
      
          if (normalImpulse > 0) normalImpulse = 0;
      
          var normalVelocity = {
              x: normal.x * normalImpulse, 
              y: normal.y * normalImpulse
          };
  
          var torque;
   
          if (bodyA && !bodyA.isStatic) {
              torque = Vector.cross(offsetA, normalVelocity) * bodyA.inverseInertia * (1 - constraint.angularStiffness);
  
              // keep track of applied impulses for post solving
              bodyA.constraintImpulse.x -= force.x;
              bodyA.constraintImpulse.y -= force.y;
              bodyA.constraintImpulse.angle += torque;
  
              // apply forces
              bodyA.position.x -= force.x;
              bodyA.position.y -= force.y;
              bodyA.angle += torque;
          }
  
          if (bodyB && !bodyB.isStatic) {
              torque = Vector.cross(offsetB, normalVelocity) * bodyB.inverseInertia * (1 - constraint.angularStiffness);
  
              // keep track of applied impulses for post solving
              bodyB.constraintImpulse.x += force.x;
              bodyB.constraintImpulse.y += force.y;
              bodyB.constraintImpulse.angle -= torque;
              
              // apply forces
              bodyB.position.x += force.x;
              bodyB.position.y += force.y;
              bodyB.angle -= torque;
          }
  
      };
  
      /**
       * Performs body updates required after solving constraints.
       * @private
       * @method postSolveAll
       * @param {body[]} bodies
       */
      Constraint.postSolveAll = function(bodies) {
          for (var i = 0; i < bodies.length; i++) {
              var body = bodies[i],
                  impulse = body.constraintImpulse;
  
              if (impulse.x === 0 && impulse.y === 0 && impulse.angle === 0) {
                  continue;
              }
  
              Sleeping.set(body, false);
  
              // update geometry and reset
              for (var j = 0; j < body.parts.length; j++) {
                  var part = body.parts[j];
                  
                  Vertices.translate(part.vertices, impulse);
  
                  if (j > 0) {
                      part.position.x += impulse.x;
                      part.position.y += impulse.y;
                  }
  
                  if (impulse.angle !== 0) {
                      Vertices.rotate(part.vertices, impulse.angle, body.position);
                      Axes.rotate(part.axes, impulse.angle);
                      if (j > 0) {
                          Vector.rotateAbout(part.position, impulse.angle, body.position, part.position);
                      }
                  }
  
                  Bounds.update(part.bounds, part.vertices, body.velocity);
              }
  
              impulse.angle = 0;
              impulse.x = 0;
              impulse.y = 0;
          }
      };
  
      /*
      *
      *  Properties Documentation
      *
      */
  
      /**
       * An integer `Number` uniquely identifying number generated in `Composite.create` by `Common.nextId`.
       *
       * @property id
       * @type number
       */
  
      /**
       * A `String` denoting the type of object.
       *
       * @property type
       * @type string
       * @default "constraint"
       */
  
      /**
       * An arbitrary `String` name to help the user identify and manage bodies.
       *
       * @property label
       * @type string
       * @default "Constraint"
       */
  
      /**
       * An `Object` that defines the rendering properties to be consumed by the module `Matter.Render`.
       *
       * @property render
       * @type object
       */
  
      /**
       * A flag that indicates if the constraint should be rendered.
       *
       * @property render.visible
       * @type boolean
       * @default true
       */
  
      /**
       * A `Number` that defines the line width to use when rendering the constraint outline.
       * A value of `0` means no outline will be rendered.
       *
       * @property render.lineWidth
       * @type number
       * @default 2
       */
  
      /**
       * A `String` that defines the stroke style to use when rendering the constraint outline.
       * It is the same as when using a canvas, so it accepts CSS style property values.
       *
       * @property render.strokeStyle
       * @type string
       * @default a random colour
       */
  
      /**
       * The first possible `Body` that this constraint is attached to.
       *
       * @property bodyA
       * @type body
       * @default null
       */
  
      /**
       * The second possible `Body` that this constraint is attached to.
       *
       * @property bodyB
       * @type body
       * @default null
       */
  
      /**
       * A `Vector` that specifies the offset of the constraint from center of the `constraint.bodyA` if defined, otherwise a world-space position.
       *
       * @property pointA
       * @type vector
       * @default { x: 0, y: 0 }
       */
  
      /**
       * A `Vector` that specifies the offset of the constraint from center of the `constraint.bodyA` if defined, otherwise a world-space position.
       *
       * @property pointB
       * @type vector
       * @default { x: 0, y: 0 }
       */
  
      /**
       * A `Number` that specifies the stiffness of the constraint, i.e. the rate at which it returns to its resting `constraint.length`.
       * A value of `1` means the constraint should be very stiff.
       * A value of `0.2` means the constraint acts like a soft spring.
       *
       * @property stiffness
       * @type number
       * @default 1
       */
  
      /**
       * A `Number` that specifies the target resting length of the constraint. 
       * It is calculated automatically in `Constraint.create` from initial positions of the `constraint.bodyA` and `constraint.bodyB`.
       *
       * @property length
       * @type number
       */
  
  })();
  
  },{"../core/Common":14,"../core/Sleeping":20,"../geometry/Axes":23,"../geometry/Bounds":24,"../geometry/Vector":26,"../geometry/Vertices":27}],13:[function(require,module,exports){
  /**
  * The `Matter.MouseConstraint` module contains methods for creating mouse constraints.
  * Mouse constraints are used for allowing user interaction, providing the ability to move bodies via the mouse or touch.
  *
  * See the included usage [examples](https://github.com/liabru/matter-js/tree/master/examples).
  *
  * @class MouseConstraint
  */
  
  var MouseConstraint = {};
  
  module.exports = MouseConstraint;
  
  var Vertices = require('../geometry/Vertices');
  var Sleeping = require('../core/Sleeping');
  var Mouse = require('../core/Mouse');
  var Events = require('../core/Events');
  var Detector = require('../collision/Detector');
  var Constraint = require('./Constraint');
  var Composite = require('../body/Composite');
  var Common = require('../core/Common');
  var Bounds = require('../geometry/Bounds');
  
  (function() {
  
      /**
       * Creates a new mouse constraint.
       * All properties have default values, and many are pre-calculated automatically based on other properties.
       * See the properties section below for detailed information on what you can pass via the `options` object.
       * @method create
       * @param {engine} engine
       * @param {} options
       * @return {MouseConstraint} A new MouseConstraint
       */
      MouseConstraint.create = function(engine, options) {
          var mouse = (engine ? engine.mouse : null) || (options ? options.mouse : null);
  
          if (!mouse) {
              if (engine && engine.render && engine.render.canvas) {
                  mouse = Mouse.create(engine.render.canvas);
              } else {
                  mouse = Mouse.create();
                  Common.log('MouseConstraint.create: options.mouse was undefined, engine.render.canvas was undefined, may not function as expected', 'warn');
              }
          }
  
          var constraint = Constraint.create({ 
              label: 'Mouse Constraint',
              pointA: mouse.position,
              pointB: { x: 0, y: 0 },
              length: 0.01, 
              stiffness: 0.1,
              angularStiffness: 1,
              render: {
                  strokeStyle: '#90EE90',
                  lineWidth: 3
              }
          });
  
          var defaults = {
              type: 'mouseConstraint',
              mouse: mouse,
              body: null,
              constraint: constraint,
              collisionFilter: {
                  category: 0x0001,
                  mask: 0xFFFFFFFF,
                  group: 0
              }
          };
  
          var mouseConstraint = Common.extend(defaults, options);
  
          Events.on(engine, 'tick', function() {
              var allBodies = Composite.allBodies(engine.world);
              MouseConstraint.update(mouseConstraint, allBodies);
              _triggerEvents(mouseConstraint);
          });
  
          return mouseConstraint;
      };
  
      /**
       * Updates the given mouse constraint.
       * @private
       * @method update
       * @param {MouseConstraint} mouseConstraint
       * @param {body[]} bodies
       */
      MouseConstraint.update = function(mouseConstraint, bodies) {
          var mouse = mouseConstraint.mouse,
              constraint = mouseConstraint.constraint,
              body = mouseConstraint.body;
  
          if (mouse.button === 0) {
              if (!constraint.bodyB) {
                  for (var i = 0; i < bodies.length; i++) {
                      body = bodies[i];
                      if (Bounds.contains(body.bounds, mouse.position) 
                              && Detector.canCollide(body.collisionFilter, mouseConstraint.collisionFilter)) {
                          for (var j = body.parts.length > 1 ? 1 : 0; j < body.parts.length; j++) {
                              var part = body.parts[j];
                              if (Vertices.contains(part.vertices, mouse.position)) {
                                  constraint.pointA = mouse.position;
                                  constraint.bodyB = mouseConstraint.body = body;
                                  constraint.pointB = { x: mouse.position.x - body.position.x, y: mouse.position.y - body.position.y };
                                  constraint.angleB = body.angle;
  
                                  Sleeping.set(body, false);
                                  Events.trigger(mouseConstraint, 'startdrag', { mouse: mouse, body: body });
  
                                  break;
                              }
                          }
                      }
                  }
              } else {
                  Sleeping.set(constraint.bodyB, false);
                  constraint.pointA = mouse.position;
              }
          } else {
              constraint.bodyB = mouseConstraint.body = null;
              constraint.pointB = null;
  
              if (body)
                  Events.trigger(mouseConstraint, 'enddrag', { mouse: mouse, body: body });
          }
      };
  
      /**
       * Triggers mouse constraint events.
       * @method _triggerEvents
       * @private
       * @param {mouse} mouseConstraint
       */
      var _triggerEvents = function(mouseConstraint) {
          var mouse = mouseConstraint.mouse,
              mouseEvents = mouse.sourceEvents;
  
          if (mouseEvents.mousemove)
              Events.trigger(mouseConstraint, 'mousemove', { mouse: mouse });
  
          if (mouseEvents.mousedown)
              Events.trigger(mouseConstraint, 'mousedown', { mouse: mouse });
  
          if (mouseEvents.mouseup)
              Events.trigger(mouseConstraint, 'mouseup', { mouse: mouse });
  
          // reset the mouse state ready for the next step
          Mouse.clearSourceEvents(mouse);
      };
  
      /*
      *
      *  Events Documentation
      *
      */
  
      /**
      * Fired when the mouse has moved (or a touch moves) during the last step
      *
      * @event mousemove
      * @param {} event An event object
      * @param {mouse} event.mouse The engine's mouse instance
      * @param {} event.source The source object of the event
      * @param {} event.name The name of the event
      */
  
      /**
      * Fired when the mouse is down (or a touch has started) during the last step
      *
      * @event mousedown
      * @param {} event An event object
      * @param {mouse} event.mouse The engine's mouse instance
      * @param {} event.source The source object of the event
      * @param {} event.name The name of the event
      */
  
      /**
      * Fired when the mouse is up (or a touch has ended) during the last step
      *
      * @event mouseup
      * @param {} event An event object
      * @param {mouse} event.mouse The engine's mouse instance
      * @param {} event.source The source object of the event
      * @param {} event.name The name of the event
      */
  
      /**
      * Fired when the user starts dragging a body
      *
      * @event startdrag
      * @param {} event An event object
      * @param {mouse} event.mouse The engine's mouse instance
      * @param {body} event.body The body being dragged
      * @param {} event.source The source object of the event
      * @param {} event.name The name of the event
      */
  
      /**
      * Fired when the user ends dragging a body
      *
      * @event enddrag
      * @param {} event An event object
      * @param {mouse} event.mouse The engine's mouse instance
      * @param {body} event.body The body that has stopped being dragged
      * @param {} event.source The source object of the event
      * @param {} event.name The name of the event
      */
  
      /*
      *
      *  Properties Documentation
      *
      */
  
      /**
       * A `String` denoting the type of object.
       *
       * @property type
       * @type string
       * @default "constraint"
       */
  
      /**
       * The `Mouse` instance in use. If not supplied in `MouseConstraint.create`, one will be created.
       *
       * @property mouse
       * @type mouse
       * @default mouse
       */
  
      /**
       * The `Body` that is currently being moved by the user, or `null` if no body.
       *
       * @property body
       * @type body
       * @default null
       */
  
      /**
       * The `Constraint` object that is used to move the body during interaction.
       *
       * @property constraint
       * @type constraint
       */
  
      /**
       * An `Object` that specifies the collision filter properties.
       * The collision filter allows the user to define which types of body this mouse constraint can interact with.
       * See `body.collisionFilter` for more information.
       *
       * @property collisionFilter
       * @type object
       */
  
  })();
  
  },{"../body/Composite":2,"../collision/Detector":5,"../core/Common":14,"../core/Events":16,"../core/Mouse":18,"../core/Sleeping":20,"../geometry/Bounds":24,"../geometry/Vertices":27,"./Constraint":12}],14:[function(require,module,exports){
  /**
  * The `Matter.Common` module contains utility functions that are common to all modules.
  *
  * @class Common
  */
  
  var Common = {};
  
  module.exports = Common;
  
  (function() {
  
      Common._nextId = 0;
      Common._seed = 0;
  
      /**
       * Extends the object in the first argument using the object in the second argument.
       * @method extend
       * @param {} obj
       * @param {boolean} deep
       * @return {} obj extended
       */
      Common.extend = function(obj, deep) {
          var argsStart,
              args,
              deepClone;
  
          if (typeof deep === 'boolean') {
              argsStart = 2;
              deepClone = deep;
          } else {
              argsStart = 1;
              deepClone = true;
          }
  
          args = Array.prototype.slice.call(arguments, argsStart);
  
          for (var i = 0; i < args.length; i++) {
              var source = args[i];
  
              if (source) {
                  for (var prop in source) {
                      if (deepClone && source[prop] && source[prop].constructor === Object) {
                          if (!obj[prop] || obj[prop].constructor === Object) {
                              obj[prop] = obj[prop] || {};
                              Common.extend(obj[prop], deepClone, source[prop]);
                          } else {
                              obj[prop] = source[prop];
                          }
                      } else {
                          obj[prop] = source[prop];
                      }
                  }
              }
          }
          
          return obj;
      };
  
      /**
       * Creates a new clone of the object, if deep is true references will also be cloned.
       * @method clone
       * @param {} obj
       * @param {bool} deep
       * @return {} obj cloned
       */
      Common.clone = function(obj, deep) {
          return Common.extend({}, deep, obj);
      };
  
      /**
       * Returns the list of keys for the given object.
       * @method keys
       * @param {} obj
       * @return {string[]} keys
       */
      Common.keys = function(obj) {
          if (Object.keys)
              return Object.keys(obj);
  
          // avoid hasOwnProperty for performance
          var keys = [];
          for (var key in obj)
              keys.push(key);
          return keys;
      };
  
      /**
       * Returns the list of values for the given object.
       * @method values
       * @param {} obj
       * @return {array} Array of the objects property values
       */
      Common.values = function(obj) {
          var values = [];
          
          if (Object.keys) {
              var keys = Object.keys(obj);
              for (var i = 0; i < keys.length; i++) {
                  values.push(obj[keys[i]]);
              }
              return values;
          }
          
          // avoid hasOwnProperty for performance
          for (var key in obj)
              values.push(obj[key]);
          return values;
      };
  
      /**
       * Returns a hex colour string made by lightening or darkening color by percent.
       * @method shadeColor
       * @param {string} color
       * @param {number} percent
       * @return {string} A hex colour
       */
      Common.shadeColor = function(color, percent) {   
          // http://stackoverflow.com/questions/5560248/programmatically-lighten-or-darken-a-hex-color
          var colorInteger = parseInt(color.slice(1),16), 
              amount = Math.round(2.55 * percent), 
              R = (colorInteger >> 16) + amount, 
              B = (colorInteger >> 8 & 0x00FF) + amount, 
              G = (colorInteger & 0x0000FF) + amount;
          return "#" + (0x1000000 + (R < 255 ? R < 1 ? 0 : R :255) * 0x10000 
                  + (B < 255 ? B < 1 ? 0 : B : 255) * 0x100 
                  + (G < 255 ? G < 1 ? 0 : G : 255)).toString(16).slice(1);
      };
  
      /**
       * Shuffles the given array in-place.
       * The function uses a seeded random generator.
       * @method shuffle
       * @param {array} array
       * @return {array} array shuffled randomly
       */
      Common.shuffle = function(array) {
          for (var i = array.length - 1; i > 0; i--) {
              var j = Math.floor(Common.random() * (i + 1));
              var temp = array[i];
              array[i] = array[j];
              array[j] = temp;
          }
          return array;
      };
  
      /**
       * Randomly chooses a value from a list with equal probability.
       * The function uses a seeded random generator.
       * @method choose
       * @param {array} choices
       * @return {object} A random choice object from the array
       */
      Common.choose = function(choices) {
          return choices[Math.floor(Common.random() * choices.length)];
      };
  
      /**
       * Returns true if the object is a HTMLElement, otherwise false.
       * @method isElement
       * @param {object} obj
       * @return {boolean} True if the object is a HTMLElement, otherwise false
       */
      Common.isElement = function(obj) {
          // http://stackoverflow.com/questions/384286/javascript-isdom-how-do-you-check-if-a-javascript-object-is-a-dom-object
          try {
              return obj instanceof HTMLElement;
          }
          catch(e){
              return (typeof obj==="object") &&
                (obj.nodeType===1) && (typeof obj.style === "object") &&
                (typeof obj.ownerDocument ==="object");
          }
      };
  
      /**
       * Returns true if the object is an array.
       * @method isArray
       * @param {object} obj
       * @return {boolean} True if the object is an array, otherwise false
       */
      Common.isArray = function(obj) {
          return Object.prototype.toString.call(obj) === '[object Array]';
      };
      
      /**
       * Returns the given value clamped between a minimum and maximum value.
       * @method clamp
       * @param {number} value
       * @param {number} min
       * @param {number} max
       * @return {number} The value clamped between min and max inclusive
       */
      Common.clamp = function(value, min, max) {
          if (value < min)
              return min;
          if (value > max)
              return max;
          return value;
      };
      
      /**
       * Returns the sign of the given value.
       * @method sign
       * @param {number} value
       * @return {number} -1 if negative, +1 if 0 or positive
       */
      Common.sign = function(value) {
          return value < 0 ? -1 : 1;
      };
      
      /**
       * Returns the current timestamp (high-res if available).
       * @method now
       * @return {number} the current timestamp (high-res if available)
       */
      Common.now = function() {
          // http://stackoverflow.com/questions/221294/how-do-you-get-a-timestamp-in-javascript
          // https://gist.github.com/davidwaterston/2982531
  
          var performance = window.performance || {};
  
          performance.now = (function() {
              return performance.now    ||
              performance.webkitNow     ||
              performance.msNow         ||
              performance.oNow          ||
              performance.mozNow        ||
              function() { return +(new Date()); };
          })();
                
          return performance.now();
      };
  
      
      /**
       * Returns a random value between a minimum and a maximum value inclusive.
       * The function uses a seeded random generator.
       * @method random
       * @param {number} min
       * @param {number} max
       * @return {number} A random number between min and max inclusive
       */
      Common.random = function(min, max) {
          min = (typeof min !== "undefined") ? min : 0;
          max = (typeof max !== "undefined") ? max : 1;
          return min + _seededRandom() * (max - min);
      };
  
      /**
       * Converts a CSS hex colour string into an integer.
       * @method colorToNumber
       * @param {string} colorString
       * @return {number} An integer representing the CSS hex string
       */
      Common.colorToNumber = function(colorString) {
          colorString = colorString.replace('#','');
  
          if (colorString.length == 3) {
              colorString = colorString.charAt(0) + colorString.charAt(0)
                          + colorString.charAt(1) + colorString.charAt(1)
                          + colorString.charAt(2) + colorString.charAt(2);
          }
  
          return parseInt(colorString, 16);
      };
  
      /**
       * A wrapper for console.log, for providing errors and warnings.
       * @method log
       * @param {string} message
       * @param {string} type
       */
      Common.log = function(message, type) {
          if (!console || !console.log || !console.warn)
              return;
  
          switch (type) {
  
          case 'warn':
              console.warn('Matter.js:', message);
              break;
          case 'error':
              console.log('Matter.js:', message);
              break;
  
          }
      };
  
      /**
       * Returns the next unique sequential ID.
       * @method nextId
       * @return {Number} Unique sequential ID
       */
      Common.nextId = function() {
          return Common._nextId++;
      };
  
      /**
       * A cross browser compatible indexOf implementation.
       * @method indexOf
       * @param {array} haystack
       * @param {object} needle
       */
      Common.indexOf = function(haystack, needle) {
          if (haystack.indexOf)
              return haystack.indexOf(needle);
  
          for (var i = 0; i < haystack.length; i++) {
              if (haystack[i] === needle)
                  return i;
          }
  
          return -1;
      };
  
      var _seededRandom = function() {
          // https://gist.github.com/ngryman/3830489
          Common._seed = (Common._seed * 9301 + 49297) % 233280;
          return Common._seed / 233280;
      };
  
  })();
  
  },{}],15:[function(require,module,exports){
  /**
  * The `Matter.Engine` module contains methods for creating and manipulating engines.
  * An engine is a controller that manages updating the simulation of the world.
  * See `Matter.Runner` for an optional game loop utility.
  *
  * See the included usage [examples](https://github.com/liabru/matter-js/tree/master/examples).
  *
  * @class Engine
  */
  
  var Engine = {};
  
  module.exports = Engine;
  
  var World = require('../body/World');
  var Sleeping = require('./Sleeping');
  var Resolver = require('../collision/Resolver');
  var Render = require('../render/Render');
  var Pairs = require('../collision/Pairs');
  var Metrics = require('./Metrics');
  var Grid = require('../collision/Grid');
  var Events = require('./Events');
  var Composite = require('../body/Composite');
  var Constraint = require('../constraint/Constraint');
  var Common = require('./Common');
  var Body = require('../body/Body');
  
  (function() {
  
      /**
       * Creates a new engine. The options parameter is an object that specifies any properties you wish to override the defaults.
       * All properties have default values, and many are pre-calculated automatically based on other properties.
       * See the properties section below for detailed information on what you can pass via the `options` object.
       * @method create
       * @param {HTMLElement} element
       * @param {object} [options]
       * @return {engine} engine
       */
      Engine.create = function(element, options) {
  
          // options may be passed as the first (and only) argument
          options = Common.isElement(element) ? options : element;
          element = Common.isElement(element) ? element : null;
  
          var defaults = {
              positionIterations: 6,
              velocityIterations: 4,
              constraintIterations: 2,
              enableSleeping: false,
              events: [],
              timing: {
                  timestamp: 0,
                  timeScale: 1
              },
              broadphase: {
                  controller: Grid
              }
          };
  
          var engine = Common.extend(defaults, options);
  
          if (element || engine.render) {
              var renderDefaults = {
                  element: element,
                  controller: Render
              };
              
              engine.render = Common.extend(renderDefaults, engine.render);
          }
  
          if (engine.render && engine.render.controller) {
              engine.render = engine.render.controller.create(engine.render);
          }
  
          engine.world = World.create(engine.world);
          engine.pairs = Pairs.create();
          engine.broadphase = engine.broadphase.controller.create(engine.broadphase);
          engine.metrics = engine.metrics || { extended: false };
  
  
          return engine;
      };
  
      /**
       * Moves the simulation forward in time by `delta` ms.
       * The `correction` argument is an optional `Number` that specifies the time correction factor to apply to the update.
       * This can help improve the accuracy of the simulation in cases where `delta` is changing between updates.
       * The value of `correction` is defined as `delta / lastDelta`, i.e. the percentage change of `delta` over the last step.
       * Therefore the value is always `1` (no correction) when `delta` constant (or when no correction is desired, which is the default).
       * See the paper on <a href="http://lonesock.net/article/verlet.html">Time Corrected Verlet</a> for more information.
       *
       * Triggers `beforeUpdate` and `afterUpdate` events.
       * Triggers `collisionStart`, `collisionActive` and `collisionEnd` events.
       * @method update
       * @param {engine} engine
       * @param {number} delta
       * @param {number} [correction]
       */
      Engine.update = function(engine, delta, correction) {
          correction = (typeof correction !== 'undefined') ? correction : 1;
  
          var world = engine.world,
              timing = engine.timing,
              broadphase = engine.broadphase,
              broadphasePairs = [],
              i;
  
          // increment timestamp
          timing.timestamp += delta * timing.timeScale;
  
          // create an event object
          var event = {
              timestamp: timing.timestamp
          };
  
          Events.trigger(engine, 'beforeUpdate', event);
  
          // get lists of all bodies and constraints, no matter what composites they are in
          var allBodies = Composite.allBodies(world),
              allConstraints = Composite.allConstraints(world);
  
  
          // if sleeping enabled, call the sleeping controller
          if (engine.enableSleeping)
              Sleeping.update(allBodies, timing.timeScale);
  
          // applies gravity to all bodies
          _bodiesApplyGravity(allBodies, world.gravity);
  
          // update all body position and rotation by integration
          _bodiesUpdate(allBodies, delta, timing.timeScale, correction, world.bounds);
  
          // update all constraints
          for (i = 0; i < engine.constraintIterations; i++) {
              Constraint.solveAll(allConstraints, timing.timeScale);
          }
          Constraint.postSolveAll(allBodies);
  
          // broadphase pass: find potential collision pairs
          if (broadphase.controller) {
  
              // if world is dirty, we must flush the whole grid
              if (world.isModified)
                  broadphase.controller.clear(broadphase);
  
              // update the grid buckets based on current bodies
              broadphase.controller.update(broadphase, allBodies, engine, world.isModified);
              broadphasePairs = broadphase.pairsList;
          } else {
  
              // if no broadphase set, we just pass all bodies
              broadphasePairs = allBodies;
          }
  
          // narrowphase pass: find actual collisions, then create or update collision pairs
          var collisions = broadphase.detector(broadphasePairs, engine);
  
          // update collision pairs
          var pairs = engine.pairs,
              timestamp = timing.timestamp;
          Pairs.update(pairs, collisions, timestamp);
          Pairs.removeOld(pairs, timestamp);
  
          // wake up bodies involved in collisions
          if (engine.enableSleeping)
              Sleeping.afterCollisions(pairs.list, timing.timeScale);
  
          // trigger collision events
          if (pairs.collisionStart.length > 0)
              Events.trigger(engine, 'collisionStart', { pairs: pairs.collisionStart });
  
          // iteratively resolve position between collisions
          Resolver.preSolvePosition(pairs.list);
          for (i = 0; i < engine.positionIterations; i++) {
              Resolver.solvePosition(pairs.list, timing.timeScale);
          }
          Resolver.postSolvePosition(allBodies);
  
          // iteratively resolve velocity between collisions
          Resolver.preSolveVelocity(pairs.list);
          for (i = 0; i < engine.velocityIterations; i++) {
              Resolver.solveVelocity(pairs.list, timing.timeScale);
          }
  
          // trigger collision events
          if (pairs.collisionActive.length > 0)
              Events.trigger(engine, 'collisionActive', { pairs: pairs.collisionActive });
  
          if (pairs.collisionEnd.length > 0)
              Events.trigger(engine, 'collisionEnd', { pairs: pairs.collisionEnd });
  
  
          // clear force buffers
          _bodiesClearForces(allBodies);
  
          // clear all composite modified flags
          if (world.isModified)
              Composite.setModified(world, false, false, true);
  
          Events.trigger(engine, 'afterUpdate', event);
  
          return engine;
      };
      
      /**
       * Merges two engines by keeping the configuration of `engineA` but replacing the world with the one from `engineB`.
       * @method merge
       * @param {engine} engineA
       * @param {engine} engineB
       */
      Engine.merge = function(engineA, engineB) {
          Common.extend(engineA, engineB);
          
          if (engineB.world) {
              engineA.world = engineB.world;
  
              Engine.clear(engineA);
  
              var bodies = Composite.allBodies(engineA.world);
  
              for (var i = 0; i < bodies.length; i++) {
                  var body = bodies[i];
                  Sleeping.set(body, false);
                  body.id = Common.nextId();
              }
          }
      };
  
      /**
       * Clears the engine including the world, pairs and broadphase.
       * @method clear
       * @param {engine} engine
       */
      Engine.clear = function(engine) {
          var world = engine.world;
          
          Pairs.clear(engine.pairs);
  
          var broadphase = engine.broadphase;
          if (broadphase.controller) {
              var bodies = Composite.allBodies(world);
              broadphase.controller.clear(broadphase);
              broadphase.controller.update(broadphase, bodies, engine, true);
          }
      };
  
      /**
       * Zeroes the `body.force` and `body.torque` force buffers.
       * @method bodiesClearForces
       * @private
       * @param {body[]} bodies
       */
      var _bodiesClearForces = function(bodies) {
          for (var i = 0; i < bodies.length; i++) {
              var body = bodies[i];
  
              // reset force buffers
              body.force.x = 0;
              body.force.y = 0;
              body.torque = 0;
          }
      };
  
      /**
       * Applys a mass dependant force to all given bodies.
       * @method bodiesApplyGravity
       * @private
       * @param {body[]} bodies
       * @param {vector} gravity
       */
      var _bodiesApplyGravity = function(bodies, gravity) {
          var gravityScale = typeof gravity.scale !== 'undefined' ? gravity.scale : 0.001;
  
          if ((gravity.x === 0 && gravity.y === 0) || gravityScale === 0) {
              return;
          }
          
          for (var i = 0; i < bodies.length; i++) {
              var body = bodies[i];
  
              if (body.isStatic || body.isSleeping)
                  continue;
  
              // apply gravity
              body.force.y += body.mass * gravity.y * gravityScale;
              body.force.x += body.mass * gravity.x * gravityScale;
          }
      };
  
      /**
       * Applys `Body.update` to all given `bodies`.
       * @method updateAll
       * @private
       * @param {body[]} bodies
       * @param {number} deltaTime 
       * The amount of time elapsed between updates
       * @param {number} timeScale
       * @param {number} correction 
       * The Verlet correction factor (deltaTime / lastDeltaTime)
       * @param {bounds} worldBounds
       */
      var _bodiesUpdate = function(bodies, deltaTime, timeScale, correction, worldBounds) {
          for (var i = 0; i < bodies.length; i++) {
              var body = bodies[i];
  
              if (body.isStatic || body.isSleeping)
                  continue;
  
              Body.update(body, deltaTime, timeScale, correction);
          }
      };
  
      /**
       * An alias for `Runner.run`, see `Matter.Runner` for more information.
       * @method run
       * @param {engine} engine
       */
  
      /**
      * Fired just before an update
      *
      * @event beforeUpdate
      * @param {} event An event object
      * @param {number} event.timestamp The engine.timing.timestamp of the event
      * @param {} event.source The source object of the event
      * @param {} event.name The name of the event
      */
  
      /**
      * Fired after engine update and all collision events
      *
      * @event afterUpdate
      * @param {} event An event object
      * @param {number} event.timestamp The engine.timing.timestamp of the event
      * @param {} event.source The source object of the event
      * @param {} event.name The name of the event
      */
  
      /**
      * Fired after engine update, provides a list of all pairs that have started to collide in the current tick (if any)
      *
      * @event collisionStart
      * @param {} event An event object
      * @param {} event.pairs List of affected pairs
      * @param {number} event.timestamp The engine.timing.timestamp of the event
      * @param {} event.source The source object of the event
      * @param {} event.name The name of the event
      */
  
      /**
      * Fired after engine update, provides a list of all pairs that are colliding in the current tick (if any)
      *
      * @event collisionActive
      * @param {} event An event object
      * @param {} event.pairs List of affected pairs
      * @param {number} event.timestamp The engine.timing.timestamp of the event
      * @param {} event.source The source object of the event
      * @param {} event.name The name of the event
      */
  
      /**
      * Fired after engine update, provides a list of all pairs that have ended collision in the current tick (if any)
      *
      * @event collisionEnd
      * @param {} event An event object
      * @param {} event.pairs List of affected pairs
      * @param {number} event.timestamp The engine.timing.timestamp of the event
      * @param {} event.source The source object of the event
      * @param {} event.name The name of the event
      */
  
      /*
      *
      *  Properties Documentation
      *
      */
  
      /**
       * An integer `Number` that specifies the number of position iterations to perform each update.
       * The higher the value, the higher quality the simulation will be at the expense of performance.
       *
       * @property positionIterations
       * @type number
       * @default 6
       */
  
      /**
       * An integer `Number` that specifies the number of velocity iterations to perform each update.
       * The higher the value, the higher quality the simulation will be at the expense of performance.
       *
       * @property velocityIterations
       * @type number
       * @default 4
       */
  
      /**
       * An integer `Number` that specifies the number of constraint iterations to perform each update.
       * The higher the value, the higher quality the simulation will be at the expense of performance.
       * The default value of `2` is usually very adequate.
       *
       * @property constraintIterations
       * @type number
       * @default 2
       */
  
      /**
       * A flag that specifies whether the engine should allow sleeping via the `Matter.Sleeping` module.
       * Sleeping can improve stability and performance, but often at the expense of accuracy.
       *
       * @property enableSleeping
       * @type boolean
       * @default false
       */
  
      /**
       * An `Object` containing properties regarding the timing systems of the engine. 
       *
       * @property timing
       * @type object
       */
  
      /**
       * A `Number` that specifies the global scaling factor of time for all bodies.
       * A value of `0` freezes the simulation.
       * A value of `0.1` gives a slow-motion effect.
       * A value of `1.2` gives a speed-up effect.
       *
       * @property timing.timeScale
       * @type number
       * @default 1
       */
  
      /**
       * A `Number` that specifies the current simulation-time in milliseconds starting from `0`. 
       * It is incremented on every `Engine.update` by the given `delta` argument. 
       *
       * @property timing.timestamp
       * @type number
       * @default 0
       */
  
      /**
       * An instance of a `Render` controller. The default value is a `Matter.Render` instance created by `Engine.create`.
       * One may also develop a custom renderer module based on `Matter.Render` and pass an instance of it to `Engine.create` via `options.render`.
       *
       * A minimal custom renderer object must define at least three functions: `create`, `clear` and `world` (see `Matter.Render`).
       * It is also possible to instead pass the _module_ reference via `options.render.controller` and `Engine.create` will instantiate one for you.
       *
       * @property render
       * @type render
       * @default a Matter.Render instance
       */
  
      /**
       * An instance of a broadphase controller. The default value is a `Matter.Grid` instance created by `Engine.create`.
       *
       * @property broadphase
       * @type grid
       * @default a Matter.Grid instance
       */
  
      /**
       * A `World` composite object that will contain all simulated bodies and constraints.
       *
       * @property world
       * @type world
       * @default a Matter.World instance
       */
  
  })();
  
  },{"../body/Body":1,"../body/Composite":2,"../body/World":3,"../collision/Grid":6,"../collision/Pairs":8,"../collision/Resolver":10,"../constraint/Constraint":12,"../render/Render":29,"./Common":14,"./Events":16,"./Metrics":17,"./Sleeping":20}],16:[function(require,module,exports){
  /**
  * The `Matter.Events` module contains methods to fire and listen to events on other objects.
  *
  * See the included usage [examples](https://github.com/liabru/matter-js/tree/master/examples).
  *
  * @class Events
  */
  
  var Events = {};
  
  module.exports = Events;
  
  var Common = require('./Common');
  
  (function() {
  
      /**
       * Subscribes a callback function to the given object's `eventName`.
       * @method on
       * @param {} object
       * @param {string} eventNames
       * @param {function} callback
       */
      Events.on = function(object, eventNames, callback) {
          var names = eventNames.split(' '),
              name;
  
          for (var i = 0; i < names.length; i++) {
              name = names[i];
              object.events = object.events || {};
              object.events[name] = object.events[name] || [];
              object.events[name].push(callback);
          }
  
          return callback;
      };
  
      /**
       * Removes the given event callback. If no callback, clears all callbacks in `eventNames`. If no `eventNames`, clears all events.
       * @method off
       * @param {} object
       * @param {string} eventNames
       * @param {function} callback
       */
      Events.off = function(object, eventNames, callback) {
          if (!eventNames) {
              object.events = {};
              return;
          }
  
          // handle Events.off(object, callback)
          if (typeof eventNames === 'function') {
              callback = eventNames;
              eventNames = Common.keys(object.events).join(' ');
          }
  
          var names = eventNames.split(' ');
  
          for (var i = 0; i < names.length; i++) {
              var callbacks = object.events[names[i]],
                  newCallbacks = [];
  
              if (callback && callbacks) {
                  for (var j = 0; j < callbacks.length; j++) {
                      if (callbacks[j] !== callback)
                          newCallbacks.push(callbacks[j]);
                  }
              }
  
              object.events[names[i]] = newCallbacks;
          }
      };
  
      /**
       * Fires all the callbacks subscribed to the given object's `eventName`, in the order they subscribed, if any.
       * @method trigger
       * @param {} object
       * @param {string} eventNames
       * @param {} event
       */
      Events.trigger = function(object, eventNames, event) {
          var names,
              name,
              callbacks,
              eventClone;
  
          if (object.events) {
              if (!event)
                  event = {};
  
              names = eventNames.split(' ');
  
              for (var i = 0; i < names.length; i++) {
                  name = names[i];
                  callbacks = object.events[name];
  
                  if (callbacks) {
                      eventClone = Common.clone(event, false);
                      eventClone.name = name;
                      eventClone.source = object;
  
                      for (var j = 0; j < callbacks.length; j++) {
                          callbacks[j].apply(object, [eventClone]);
                      }
                  }
              }
          }
      };
  
  })();
  
  },{"./Common":14}],17:[function(require,module,exports){
  
  },{"../body/Composite":2,"./Common":14}],18:[function(require,module,exports){
  /**
  * The `Matter.Mouse` module contains methods for creating and manipulating mouse inputs.
  *
  * @class Mouse
  */
  
  var Mouse = {};
  
  module.exports = Mouse;
  
  var Common = require('../core/Common');
  
  (function() {
  
      /**
       * Creates a mouse input.
       * @method create
       * @param {HTMLElement} element
       * @return {mouse} A new mouse
       */
      Mouse.create = function(element) {
          var mouse = {};
  
          if (!element) {
              Common.log('Mouse.create: element was undefined, defaulting to document.body', 'warn');
          }
          
          mouse.element = element || document.body;
          mouse.absolute = { x: 0, y: 0 };
          mouse.position = { x: 0, y: 0 };
          mouse.mousedownPosition = { x: 0, y: 0 };
          mouse.mouseupPosition = { x: 0, y: 0 };
          mouse.offset = { x: 0, y: 0 };
          mouse.scale = { x: 1, y: 1 };
          mouse.wheelDelta = 0;
          mouse.button = -1;
          mouse.pixelRatio = mouse.element.getAttribute('data-pixel-ratio') || 1;
  
          mouse.sourceEvents = {
              mousemove: null,
              mousedown: null,
              mouseup: null,
              mousewheel: null
          };
          
          mouse.mousemove = function(event) { 
              var position = _getRelativeMousePosition(event, mouse.element, mouse.pixelRatio),
                  touches = event.changedTouches;
  
              if (touches) {
                  mouse.button = 0;
                  event.preventDefault();
              }
  
              mouse.absolute.x = position.x;
              mouse.absolute.y = position.y;
              mouse.position.x = mouse.absolute.x * mouse.scale.x + mouse.offset.x;
              mouse.position.y = mouse.absolute.y * mouse.scale.y + mouse.offset.y;
              mouse.sourceEvents.mousemove = event;
          };
          
          mouse.mousedown = function(event) {
              var position = _getRelativeMousePosition(event, mouse.element, mouse.pixelRatio),
                  touches = event.changedTouches;
  
              if (touches) {
                  mouse.button = 0;
                  event.preventDefault();
              } else {
                  mouse.button = event.button;
              }
  
              mouse.absolute.x = position.x;
              mouse.absolute.y = position.y;
              mouse.position.x = mouse.absolute.x * mouse.scale.x + mouse.offset.x;
              mouse.position.y = mouse.absolute.y * mouse.scale.y + mouse.offset.y;
              mouse.mousedownPosition.x = mouse.position.x;
              mouse.mousedownPosition.y = mouse.position.y;
              mouse.sourceEvents.mousedown = event;
          };
          
          mouse.mouseup = function(event) {
              var position = _getRelativeMousePosition(event, mouse.element, mouse.pixelRatio),
                  touches = event.changedTouches;
  
              if (touches) {
                  event.preventDefault();
              }
              
              mouse.button = -1;
              mouse.absolute.x = position.x;
              mouse.absolute.y = position.y;
              mouse.position.x = mouse.absolute.x * mouse.scale.x + mouse.offset.x;
              mouse.position.y = mouse.absolute.y * mouse.scale.y + mouse.offset.y;
              mouse.mouseupPosition.x = mouse.position.x;
              mouse.mouseupPosition.y = mouse.position.y;
              mouse.sourceEvents.mouseup = event;
          };
  
          mouse.mousewheel = function(event) {
              mouse.wheelDelta = Math.max(-1, Math.min(1, event.wheelDelta || -event.detail));
              event.preventDefault();
          };
  
          Mouse.setElement(mouse, mouse.element);
  
          return mouse;
      };
  
      /**
       * Sets the element the mouse is bound to (and relative to).
       * @method setElement
       * @param {mouse} mouse
       * @param {HTMLElement} element
       */
      Mouse.setElement = function(mouse, element) {
          mouse.element = element;
  
          element.addEventListener('mousemove', mouse.mousemove);
          element.addEventListener('mousedown', mouse.mousedown);
          element.addEventListener('mouseup', mouse.mouseup);
          
          element.addEventListener('mousewheel', mouse.mousewheel);
          element.addEventListener('DOMMouseScroll', mouse.mousewheel);
  
          element.addEventListener('touchmove', mouse.mousemove);
          element.addEventListener('touchstart', mouse.mousedown);
          element.addEventListener('touchend', mouse.mouseup);
      };
  
      /**
       * Clears all captured source events.
       * @method clearSourceEvents
       * @param {mouse} mouse
       */
      Mouse.clearSourceEvents = function(mouse) {
          mouse.sourceEvents.mousemove = null;
          mouse.sourceEvents.mousedown = null;
          mouse.sourceEvents.mouseup = null;
          mouse.sourceEvents.mousewheel = null;
          mouse.wheelDelta = 0;
      };
  
      /**
       * Sets the mouse position offset.
       * @method setOffset
       * @param {mouse} mouse
       * @param {vector} offset
       */
      Mouse.setOffset = function(mouse, offset) {
          mouse.offset.x = offset.x;
          mouse.offset.y = offset.y;
          mouse.position.x = mouse.absolute.x * mouse.scale.x + mouse.offset.x;
          mouse.position.y = mouse.absolute.y * mouse.scale.y + mouse.offset.y;
      };
  
      /**
       * Sets the mouse position scale.
       * @method setScale
       * @param {mouse} mouse
       * @param {vector} scale
       */
      Mouse.setScale = function(mouse, scale) {
          mouse.scale.x = scale.x;
          mouse.scale.y = scale.y;
          mouse.position.x = mouse.absolute.x * mouse.scale.x + mouse.offset.x;
          mouse.position.y = mouse.absolute.y * mouse.scale.y + mouse.offset.y;
      };
      
      /**
       * Gets the mouse position relative to an element given a screen pixel ratio.
       * @method _getRelativeMousePosition
       * @private
       * @param {} event
       * @param {} element
       * @param {number} pixelRatio
       * @return {}
       */
      var _getRelativeMousePosition = function(event, element, pixelRatio) {
          var elementBounds = element.getBoundingClientRect(),
              rootNode = (document.documentElement || document.body.parentNode || document.body),
              scrollX = (window.pageXOffset !== undefined) ? window.pageXOffset : rootNode.scrollLeft,
              scrollY = (window.pageYOffset !== undefined) ? window.pageYOffset : rootNode.scrollTop,
              touches = event.changedTouches,
              x, y;
          
          if (touches) {
              x = touches[0].pageX - elementBounds.left - scrollX;
              y = touches[0].pageY - elementBounds.top - scrollY;
          } else {
              x = event.pageX - elementBounds.left - scrollX;
              y = event.pageY - elementBounds.top - scrollY;
          }
  
          return { 
              x: x / (element.clientWidth / element.width * pixelRatio),
              y: y / (element.clientHeight / element.height * pixelRatio)
          };
      };
  
  })();
  
  },{"../core/Common":14}],19:[function(require,module,exports){
  /**
  * The `Matter.Runner` module is an optional utility which provides a game loop, 
  * that handles updating and rendering a `Matter.Engine` for you within a browser.
  * It is intended for demo and testing purposes, but may be adequate for simple games.
  * If you are using your own game loop instead, then you do not need the `Matter.Runner` module.
  * Instead just call `Engine.update(engine, delta)` in your own loop.
  * Note that the method `Engine.run` is an alias for `Runner.run`.
  *
  * See the included usage [examples](https://github.com/liabru/matter-js/tree/master/examples).
  *
  * @class Runner
  */
  
  var Runner = {};
  
  module.exports = Runner;
  
  var Events = require('./Events');
  var Engine = require('./Engine');
  var Common = require('./Common');
  
  (function() {
  
      var _requestAnimationFrame,
          _cancelAnimationFrame;
  
      if (typeof window !== 'undefined') {
          _requestAnimationFrame = window.requestAnimationFrame || window.webkitRequestAnimationFrame
                                        || window.mozRequestAnimationFrame || window.msRequestAnimationFrame 
                                        || function(callback){ window.setTimeout(function() { callback(Common.now()); }, 1000 / 60); };
     
          _cancelAnimationFrame = window.cancelAnimationFrame || window.mozCancelAnimationFrame 
                                        || window.webkitCancelAnimationFrame || window.msCancelAnimationFrame;
      }
  
      /**
       * Creates a new Runner. The options parameter is an object that specifies any properties you wish to override the defaults.
       * @method create
       * @param {} options
       */
      Runner.create = function(options) {
          var defaults = {
              fps: 60,
              correction: 1,
              deltaSampleSize: 60,
              counterTimestamp: 0,
              frameCounter: 0,
              deltaHistory: [],
              timePrev: null,
              timeScalePrev: 1,
              frameRequestId: null,
              isFixed: false,
              enabled: true
          };
  
          var runner = Common.extend(defaults, options);
  
          runner.delta = runner.delta || 1000 / runner.fps;
          runner.deltaMin = runner.deltaMin || 1000 / runner.fps;
          runner.deltaMax = runner.deltaMax || 1000 / (runner.fps * 0.5);
          runner.fps = 1000 / runner.delta;
  
          return runner;
      };
  
      /**
       * Continuously ticks a `Matter.Engine` by calling `Runner.tick` on the `requestAnimationFrame` event.
       * @method run
       * @param {engine} engine
       */
      Runner.run = function(runner, engine) {
          // create runner if engine is first argument
          if (typeof runner.positionIterations !== 'undefined') {
              engine = runner;
              runner = Runner.create();
          }
  
          (function render(time){
              runner.frameRequestId = _requestAnimationFrame(render);
  
              if (time && runner.enabled) {
                  Runner.tick(runner, engine, time);
              }
          })();
  
          return runner;
      };
  
      /**
       * A game loop utility that updates the engine and renderer by one step (a 'tick').
       * Features delta smoothing, time correction and fixed or dynamic timing.
       * Triggers `beforeTick`, `tick` and `afterTick` events on the engine.
       * Consider just `Engine.update(engine, delta)` if you're using your own loop.
       * @method tick
       * @param {runner} runner
       * @param {engine} engine
       * @param {number} time
       */
      Runner.tick = function(runner, engine, time) {
          var timing = engine.timing,
              correction = 1,
              delta;
  
          // create an event object
          var event = {
              timestamp: timing.timestamp
          };
  
          Events.trigger(runner, 'beforeTick', event);
          Events.trigger(engine, 'beforeTick', event); // @deprecated
  
          if (runner.isFixed) {
              // fixed timestep
              delta = runner.delta;
          } else {
              // dynamic timestep based on wall clock between calls
              delta = (time - runner.timePrev) || runner.delta;
              runner.timePrev = time;
  
              // optimistically filter delta over a few frames, to improve stability
              runner.deltaHistory.push(delta);
              runner.deltaHistory = runner.deltaHistory.slice(-runner.deltaSampleSize);
              delta = Math.min.apply(null, runner.deltaHistory);
              
              // limit delta
              delta = delta < runner.deltaMin ? runner.deltaMin : delta;
              delta = delta > runner.deltaMax ? runner.deltaMax : delta;
  
              // correction for delta
              correction = delta / runner.delta;
  
              // update engine timing object
              runner.delta = delta;
          }
  
          // time correction for time scaling
          if (runner.timeScalePrev !== 0)
              correction *= timing.timeScale / runner.timeScalePrev;
  
          if (timing.timeScale === 0)
              correction = 0;
  
          runner.timeScalePrev = timing.timeScale;
          runner.correction = correction;
  
          // fps counter
          runner.frameCounter += 1;
          if (time - runner.counterTimestamp >= 1000) {
              runner.fps = runner.frameCounter * ((time - runner.counterTimestamp) / 1000);
              runner.counterTimestamp = time;
              runner.frameCounter = 0;
          }
  
          Events.trigger(runner, 'tick', event);
          Events.trigger(engine, 'tick', event); // @deprecated
  
          // if world has been modified, clear the render scene graph
          if (engine.world.isModified 
              && engine.render
              && engine.render.controller
              && engine.render.controller.clear) {
              engine.render.controller.clear(engine.render);
          }
  
          // update
          Events.trigger(runner, 'beforeUpdate', event);
          Engine.update(engine, delta, correction);
          Events.trigger(runner, 'afterUpdate', event);
  
          // render
          if (engine.render && engine.render.controller) {
              Events.trigger(runner, 'beforeRender', event);
              Events.trigger(engine, 'beforeRender', event); // @deprecated
  
              engine.render.controller.world(engine);
  
              Events.trigger(runner, 'afterRender', event);
              Events.trigger(engine, 'afterRender', event); // @deprecated
          }
  
          Events.trigger(runner, 'afterTick', event);
          Events.trigger(engine, 'afterTick', event); // @deprecated
      };
  
      /**
       * Ends execution of `Runner.run` on the given `runner`, by canceling the animation frame request event loop.
       * If you wish to only temporarily pause the engine, see `engine.enabled` instead.
       * @method stop
       * @param {runner} runner
       */
      Runner.stop = function(runner) {
          _cancelAnimationFrame(runner.frameRequestId);
      };
  
      /**
       * Alias for `Runner.run`.
       * @method start
       * @param {runner} runner
       * @param {engine} engine
       */
      Runner.start = function(runner, engine) {
          Runner.run(runner, engine);
      };
  
      /*
      *
      *  Events Documentation
      *
      */
  
      /**
      * Fired at the start of a tick, before any updates to the engine or timing
      *
      * @event beforeTick
      * @param {} event An event object
      * @param {number} event.timestamp The engine.timing.timestamp of the event
      * @param {} event.source The source object of the event
      * @param {} event.name The name of the event
      */
  
      /**
      * Fired after engine timing updated, but just before update
      *
      * @event tick
      * @param {} event An event object
      * @param {number} event.timestamp The engine.timing.timestamp of the event
      * @param {} event.source The source object of the event
      * @param {} event.name The name of the event
      */
  
      /**
      * Fired at the end of a tick, after engine update and after rendering
      *
      * @event afterTick
      * @param {} event An event object
      * @param {number} event.timestamp The engine.timing.timestamp of the event
      * @param {} event.source The source object of the event
      * @param {} event.name The name of the event
      */
  
      /**
      * Fired before update
      *
      * @event beforeUpdate
      * @param {} event An event object
      * @param {number} event.timestamp The engine.timing.timestamp of the event
      * @param {} event.source The source object of the event
      * @param {} event.name The name of the event
      */
  
      /**
      * Fired after update
      *
      * @event afterUpdate
      * @param {} event An event object
      * @param {number} event.timestamp The engine.timing.timestamp of the event
      * @param {} event.source The source object of the event
      * @param {} event.name The name of the event
      */
  
      /**
      * Fired before rendering
      *
      * @event beforeRender
      * @param {} event An event object
      * @param {number} event.timestamp The engine.timing.timestamp of the event
      * @param {} event.source The source object of the event
      * @param {} event.name The name of the event
      */
  
      /**
      * Fired after rendering
      *
      * @event afterRender
      * @param {} event An event object
      * @param {number} event.timestamp The engine.timing.timestamp of the event
      * @param {} event.source The source object of the event
      * @param {} event.name The name of the event
      */
  
      /*
      *
      *  Properties Documentation
      *
      */
  
      /**
       * A flag that specifies whether the runner is running or not.
       *
       * @property enabled
       * @type boolean
       * @default true
       */
  
      /**
       * A `Boolean` that specifies if the runner should use a fixed timestep (otherwise it is variable).
       * If timing is fixed, then the apparent simulation speed will change depending on the frame rate (but behaviour will be deterministic).
       * If the timing is variable, then the apparent simulation speed will be constant (approximately, but at the cost of determininism).
       *
       * @property isFixed
       * @type boolean
       * @default false
       */
  
      /**
       * A `Number` that specifies the time step between updates in milliseconds.
       * If `engine.timing.isFixed` is set to `true`, then `delta` is fixed.
       * If it is `false`, then `delta` can dynamically change to maintain the correct apparent simulation speed.
       *
       * @property delta
       * @type number
       * @default 1000 / 60
       */
  
  })();
  
  },{"./Common":14,"./Engine":15,"./Events":16}],20:[function(require,module,exports){
  /**
  * The `Matter.Sleeping` module contains methods to manage the sleeping state of bodies.
  *
  * @class Sleeping
  */
  
  var Sleeping = {};
  
  module.exports = Sleeping;
  
  var Events = require('./Events');
  
  (function() {
  
      Sleeping._motionWakeThreshold = 0.18;
      Sleeping._motionSleepThreshold = 0.08;
      Sleeping._minBias = 0.9;
  
      /**
       * Puts bodies to sleep or wakes them up depending on their motion.
       * @method update
       * @param {body[]} bodies
       * @param {number} timeScale
       */
      Sleeping.update = function(bodies, timeScale) {
          var timeFactor = timeScale * timeScale * timeScale;
  
          // update bodies sleeping status
          for (var i = 0; i < bodies.length; i++) {
              var body = bodies[i],
                  motion = body.speed * body.speed + body.angularSpeed * body.angularSpeed;
  
              // wake up bodies if they have a force applied
              if (body.force.x !== 0 || body.force.y !== 0) {
                  Sleeping.set(body, false);
                  continue;
              }
  
              var minMotion = Math.min(body.motion, motion),
                  maxMotion = Math.max(body.motion, motion);
          
              // biased average motion estimation between frames
              body.motion = Sleeping._minBias * minMotion + (1 - Sleeping._minBias) * maxMotion;
              
              if (body.sleepThreshold > 0 && body.motion < Sleeping._motionSleepThreshold * timeFactor) {
                  body.sleepCounter += 1;
                  
                  if (body.sleepCounter >= body.sleepThreshold)
                      Sleeping.set(body, true);
              } else if (body.sleepCounter > 0) {
                  body.sleepCounter -= 1;
              }
          }
      };
  
      /**
       * Given a set of colliding pairs, wakes the sleeping bodies involved.
       * @method afterCollisions
       * @param {pair[]} pairs
       * @param {number} timeScale
       */
      Sleeping.afterCollisions = function(pairs, timeScale) {
          var timeFactor = timeScale * timeScale * timeScale;
  
          // wake up bodies involved in collisions
          for (var i = 0; i < pairs.length; i++) {
              var pair = pairs[i];
              
              // don't wake inactive pairs
              if (!pair.isActive)
                  continue;
  
              var collision = pair.collision,
                  bodyA = collision.bodyA.parent, 
                  bodyB = collision.bodyB.parent;
          
              // don't wake if at least one body is static
              if ((bodyA.isSleeping && bodyB.isSleeping) || bodyA.isStatic || bodyB.isStatic)
                  continue;
          
              if (bodyA.isSleeping || bodyB.isSleeping) {
                  var sleepingBody = (bodyA.isSleeping && !bodyA.isStatic) ? bodyA : bodyB,
                      movingBody = sleepingBody === bodyA ? bodyB : bodyA;
  
                  if (!sleepingBody.isStatic && movingBody.motion > Sleeping._motionWakeThreshold * timeFactor) {
                      Sleeping.set(sleepingBody, false);
                  }
              }
          }
      };
    
      /**
       * Set a body as sleeping or awake.
       * @method set
       * @param {body} body
       * @param {boolean} isSleeping
       */
      Sleeping.set = function(body, isSleeping) {
          var wasSleeping = body.isSleeping;
  
          if (isSleeping) {
              body.isSleeping = true;
              body.sleepCounter = body.sleepThreshold;
  
              body.positionImpulse.x = 0;
              body.positionImpulse.y = 0;
  
              body.positionPrev.x = body.position.x;
              body.positionPrev.y = body.position.y;
  
              body.anglePrev = body.angle;
              body.speed = 0;
              body.angularSpeed = 0;
              body.motion = 0;
  
              if (!wasSleeping) {
                  Events.trigger(body, 'sleepStart');
              }
          } else {
              body.isSleeping = false;
              body.sleepCounter = 0;
  
              if (wasSleeping) {
                  Events.trigger(body, 'sleepEnd');
              }
          }
      };
  
  })();
  
  },{"./Events":16}],21:[function(require,module,exports){
  /**
  * The `Matter.Bodies` module contains factory methods for creating rigid body models 
  * with commonly used body configurations (such as rectangles, circles and other polygons).
  *
  * See the included usage [examples](https://github.com/liabru/matter-js/tree/master/examples).
  *
  * @class Bodies
  */
  
  // TODO: true circle bodies
  
  var Bodies = {};
  
  module.exports = Bodies;
  
  var Vertices = require('../geometry/Vertices');
  var Common = require('../core/Common');
  var Body = require('../body/Body');
  var Bounds = require('../geometry/Bounds');
  var Vector = require('../geometry/Vector');
  
  (function() {
  
      /**
       * Creates a new rigid body model with a rectangle hull. 
       * The options parameter is an object that specifies any properties you wish to override the defaults.
       * See the properties section of the `Matter.Body` module for detailed information on what you can pass via the `options` object.
       * @method rectangle
       * @param {number} x
       * @param {number} y
       * @param {number} width
       * @param {number} height
       * @param {object} [options]
       * @return {body} A new rectangle body
       */
      Bodies.rectangle = function(x, y, width, height, options) {
          options = options || {};
  
          var rectangle = { 
              label: 'Rectangle Body',
              position: { x: x, y: y },
              vertices: Vertices.fromPath('L 0 0 L ' + width + ' 0 L ' + width + ' ' + height + ' L 0 ' + height)
          };
  
          if (options.chamfer) {
              var chamfer = options.chamfer;
              rectangle.vertices = Vertices.chamfer(rectangle.vertices, chamfer.radius, 
                                      chamfer.quality, chamfer.qualityMin, chamfer.qualityMax);
              delete options.chamfer;
          }
  
          return Body.create(Common.extend({}, rectangle, options));
      };
      
      /**
       * Creates a new rigid body model with a trapezoid hull. 
       * The options parameter is an object that specifies any properties you wish to override the defaults.
       * See the properties section of the `Matter.Body` module for detailed information on what you can pass via the `options` object.
       * @method trapezoid
       * @param {number} x
       * @param {number} y
       * @param {number} width
       * @param {number} height
       * @param {number} slope
       * @param {object} [options]
       * @return {body} A new trapezoid body
       */
      Bodies.trapezoid = function(x, y, width, height, slope, options) {
          options = options || {};
  
          slope *= 0.5;
          var roof = (1 - (slope * 2)) * width;
          
          var x1 = width * slope,
              x2 = x1 + roof,
              x3 = x2 + x1,
              verticesPath;
  
          if (slope < 0.5) {
              verticesPath = 'L 0 0 L ' + x1 + ' ' + (-height) + ' L ' + x2 + ' ' + (-height) + ' L ' + x3 + ' 0';
          } else {
              verticesPath = 'L 0 0 L ' + x2 + ' ' + (-height) + ' L ' + x3 + ' 0';
          }
  
          var trapezoid = { 
              label: 'Trapezoid Body',
              position: { x: x, y: y },
              vertices: Vertices.fromPath(verticesPath)
          };
  
          if (options.chamfer) {
              var chamfer = options.chamfer;
              trapezoid.vertices = Vertices.chamfer(trapezoid.vertices, chamfer.radius, 
                                      chamfer.quality, chamfer.qualityMin, chamfer.qualityMax);
              delete options.chamfer;
          }
  
          return Body.create(Common.extend({}, trapezoid, options));
      };
  
      /**
       * Creates a new rigid body model with a circle hull. 
       * The options parameter is an object that specifies any properties you wish to override the defaults.
       * See the properties section of the `Matter.Body` module for detailed information on what you can pass via the `options` object.
       * @method circle
       * @param {number} x
       * @param {number} y
       * @param {number} radius
       * @param {object} [options]
       * @param {number} [maxSides]
       * @return {body} A new circle body
       */
      Bodies.circle = function(x, y, radius, options, maxSides) {
          options = options || {};
          options.label = 'Circle Body';
          
          // approximate circles with polygons until true circles implemented in SAT
  
          maxSides = maxSides || 25;
          var sides = Math.ceil(Math.max(10, Math.min(maxSides, radius)));
  
          // optimisation: always use even number of sides (half the number of unique axes)
          if (sides % 2 === 1)
              sides += 1;
  
          // flag for better rendering
          options.circleRadius = radius;
  
          return Bodies.polygon(x, y, sides, radius, options);
      };
  
      /**
       * Creates a new rigid body model with a regular polygon hull with the given number of sides. 
       * The options parameter is an object that specifies any properties you wish to override the defaults.
       * See the properties section of the `Matter.Body` module for detailed information on what you can pass via the `options` object.
       * @method polygon
       * @param {number} x
       * @param {number} y
       * @param {number} sides
       * @param {number} radius
       * @param {object} [options]
       * @return {body} A new regular polygon body
       */
      Bodies.polygon = function(x, y, sides, radius, options) {
          options = options || {};
  
          if (sides < 3)
              return Bodies.circle(x, y, radius, options);
  
          var theta = 2 * Math.PI / sides,
              path = '',
              offset = theta * 0.5;
  
          for (var i = 0; i < sides; i += 1) {
              var angle = offset + (i * theta),
                  xx = Math.cos(angle) * radius,
                  yy = Math.sin(angle) * radius;
  
              path += 'L ' + xx.toFixed(3) + ' ' + yy.toFixed(3) + ' ';
          }
  
          var polygon = { 
              label: 'Polygon Body',
              position: { x: x, y: y },
              vertices: Vertices.fromPath(path)
          };
  
          if (options.chamfer) {
              var chamfer = options.chamfer;
              polygon.vertices = Vertices.chamfer(polygon.vertices, chamfer.radius, 
                                      chamfer.quality, chamfer.qualityMin, chamfer.qualityMax);
              delete options.chamfer;
          }
  
          return Body.create(Common.extend({}, polygon, options));
      };
  
      /**
       * Creates a body using the supplied vertices (or an array containing multiple sets of vertices).
       * If the vertices are convex, they will pass through as supplied.
       * Otherwise if the vertices are concave, they will be decomposed if [poly-decomp.js](https://github.com/schteppe/poly-decomp.js) is available.
       * Note that this process is not guaranteed to support complex sets of vertices (e.g. those with holes may fail).
       * By default the decomposition will discard collinear edges (to improve performance).
       * It can also optionally discard any parts that have an area less than `minimumArea`.
       * If the vertices can not be decomposed, the result will fall back to using the convex hull.
       * The options parameter is an object that specifies any `Matter.Body` properties you wish to override the defaults.
       * See the properties section of the `Matter.Body` module for detailed information on what you can pass via the `options` object.
       * @method fromVertices
       * @param {number} x
       * @param {number} y
       * @param [[vector]] vertexSets
       * @param {object} [options]
       * @param {bool} [flagInternal=false]
       * @param {number} [removeCollinear=0.01]
       * @param {number} [minimumArea=10]
       * @return {body}
       */
      Bodies.fromVertices = function(x, y, vertexSets, options, flagInternal, removeCollinear, minimumArea) {
          var body,
              parts,
              isConvex,
              vertices,
              i,
              j,
              k,
              v,
              z;
  
          options = options || {};
          parts = [];
  
          flagInternal = typeof flagInternal !== 'undefined' ? flagInternal : false;
          removeCollinear = typeof removeCollinear !== 'undefined' ? removeCollinear : 0.01;
          minimumArea = typeof minimumArea !== 'undefined' ? minimumArea : 10;
  
          if (!window.decomp) {
              Common.log('Bodies.fromVertices: poly-decomp.js required. Could not decompose vertices. Fallback to convex hull.', 'warn');
          }
  
          // ensure vertexSets is an array of arrays
          if (!Common.isArray(vertexSets[0])) {
              vertexSets = [vertexSets];
          }
  
          for (v = 0; v < vertexSets.length; v += 1) {
              vertices = vertexSets[v];
              isConvex = Vertices.isConvex(vertices);
  
              if (isConvex || !window.decomp) {
                  if (isConvex) {
                      vertices = Vertices.clockwiseSort(vertices);
                  } else {
                      // fallback to convex hull when decomposition is not possible
                      vertices = Vertices.hull(vertices);
                  }
  
                  parts.push({
                      position: { x: x, y: y },
                      vertices: vertices
                  });
              } else {
                  // initialise a decomposition
                  var concave = new decomp.Polygon();
                  for (i = 0; i < vertices.length; i++) {
                      concave.vertices.push([vertices[i].x, vertices[i].y]);
                  }
  
                  // vertices are concave and simple, we can decompose into parts
                  concave.makeCCW();
                  if (removeCollinear !== false)
                      concave.removeCollinearPoints(removeCollinear);
  
                  // use the quick decomposition algorithm (Bayazit)
                  var decomposed = concave.quickDecomp();
  
                  // for each decomposed chunk
                  for (i = 0; i < decomposed.length; i++) {
                      var chunk = decomposed[i],
                          chunkVertices = [];
  
                      // convert vertices into the correct structure
                      for (j = 0; j < chunk.vertices.length; j++) {
                          chunkVertices.push({ x: chunk.vertices[j][0], y: chunk.vertices[j][1] });
                      }
  
                      // skip small chunks
                      if (minimumArea > 0 && Vertices.area(chunkVertices) < minimumArea)
                          continue;
  
                      // create a compound part
                      parts.push({
                          position: Vertices.centre(chunkVertices),
                          vertices: chunkVertices
                      });
                  }
              }
          }
  
          // create body parts
          for (i = 0; i < parts.length; i++) {
              parts[i] = Body.create(Common.extend(parts[i], options));
          }
  
          // flag internal edges (coincident part edges)
          if (flagInternal) {
              var coincident_max_dist = 5;
  
              for (i = 0; i < parts.length; i++) {
                  var partA = parts[i];
  
                  for (j = i + 1; j < parts.length; j++) {
                      var partB = parts[j];
  
                      if (Bounds.overlaps(partA.bounds, partB.bounds)) {
                          var pav = partA.vertices,
                              pbv = partB.vertices;
  
                          // iterate vertices of both parts
                          for (k = 0; k < partA.vertices.length; k++) {
                              for (z = 0; z < partB.vertices.length; z++) {
                                  // find distances between the vertices
                                  var da = Vector.magnitudeSquared(Vector.sub(pav[(k + 1) % pav.length], pbv[z])),
                                      db = Vector.magnitudeSquared(Vector.sub(pav[k], pbv[(z + 1) % pbv.length]));
  
                                  // if both vertices are very close, consider the edge concident (internal)
                                  if (da < coincident_max_dist && db < coincident_max_dist) {
                                      pav[k].isInternal = true;
                                      pbv[z].isInternal = true;
                                  }
                              }
                          }
  
                      }
                  }
              }
          }
  
          if (parts.length > 1) {
              // create the parent body to be returned, that contains generated compound parts
              body = Body.create(Common.extend({ parts: parts.slice(0) }, options));
              Body.setPosition(body, { x: x, y: y });
  
              return body;
          } else {
              return parts[0];
          }
      };
  
  })();
  },{"../body/Body":1,"../core/Common":14,"../geometry/Bounds":24,"../geometry/Vector":26,"../geometry/Vertices":27}],22:[function(require,module,exports){
  /**
  * The `Matter.Composites` module contains factory methods for creating composite bodies
  * with commonly used configurations (such as stacks and chains).
  *
  * See the included usage [examples](https://github.com/liabru/matter-js/tree/master/examples).
  *
  * @class Composites
  */
  
  var Composites = {};
  
  module.exports = Composites;
  
  var Composite = require('../body/Composite');
  var Constraint = require('../constraint/Constraint');
  var Common = require('../core/Common');
  var Body = require('../body/Body');
  var Bodies = require('./Bodies');
  
  (function() {
  
      /**
       * Create a new composite containing bodies created in the callback in a grid arrangement.
       * This function uses the body's bounds to prevent overlaps.
       * @method stack
       * @param {number} xx
       * @param {number} yy
       * @param {number} columns
       * @param {number} rows
       * @param {number} columnGap
       * @param {number} rowGap
       * @param {function} callback
       * @return {composite} A new composite containing objects created in the callback
       */
      Composites.stack = function(xx, yy, columns, rows, columnGap, rowGap, callback) {
          var stack = Composite.create({ label: 'Stack' }),
              x = xx,
              y = yy,
              lastBody,
              i = 0;
  
          for (var row = 0; row < rows; row++) {
              var maxHeight = 0;
              
              for (var column = 0; column < columns; column++) {
                  var body = callback(x, y, column, row, lastBody, i);
                      
                  if (body) {
                      var bodyHeight = body.bounds.max.y - body.bounds.min.y,
                          bodyWidth = body.bounds.max.x - body.bounds.min.x; 
  
                      if (bodyHeight > maxHeight)
                          maxHeight = bodyHeight;
                      
                      Body.translate(body, { x: bodyWidth * 0.5, y: bodyHeight * 0.5 });
  
                      x = body.bounds.max.x + columnGap;
  
                      Composite.addBody(stack, body);
                      
                      lastBody = body;
                      i += 1;
                  } else {
                      x += columnGap;
                  }
              }
              
              y += maxHeight + rowGap;
              x = xx;
          }
  
          return stack;
      };
      
      /**
       * Chains all bodies in the given composite together using constraints.
       * @method chain
       * @param {composite} composite
       * @param {number} xOffsetA
       * @param {number} yOffsetA
       * @param {number} xOffsetB
       * @param {number} yOffsetB
       * @param {object} options
       * @return {composite} A new composite containing objects chained together with constraints
       */
      Composites.chain = function(composite, xOffsetA, yOffsetA, xOffsetB, yOffsetB, options) {
          var bodies = composite.bodies;
          
          for (var i = 1; i < bodies.length; i++) {
              var bodyA = bodies[i - 1],
                  bodyB = bodies[i],
                  bodyAHeight = bodyA.bounds.max.y - bodyA.bounds.min.y,
                  bodyAWidth = bodyA.bounds.max.x - bodyA.bounds.min.x, 
                  bodyBHeight = bodyB.bounds.max.y - bodyB.bounds.min.y,
                  bodyBWidth = bodyB.bounds.max.x - bodyB.bounds.min.x;
          
              var defaults = {
                  bodyA: bodyA,
                  pointA: { x: bodyAWidth * xOffsetA, y: bodyAHeight * yOffsetA },
                  bodyB: bodyB,
                  pointB: { x: bodyBWidth * xOffsetB, y: bodyBHeight * yOffsetB }
              };
              
              var constraint = Common.extend(defaults, options);
          
              Composite.addConstraint(composite, Constraint.create(constraint));
          }
  
          composite.label += ' Chain';
          
          return composite;
      };
  
      /**
       * Connects bodies in the composite with constraints in a grid pattern, with optional cross braces.
       * @method mesh
       * @param {composite} composite
       * @param {number} columns
       * @param {number} rows
       * @param {boolean} crossBrace
       * @param {object} options
       * @return {composite} The composite containing objects meshed together with constraints
       */
      Composites.mesh = function(composite, columns, rows, crossBrace, options) {
          var bodies = composite.bodies,
              row,
              col,
              bodyA,
              bodyB,
              bodyC;
          
          for (row = 0; row < rows; row++) {
              for (col = 1; col < columns; col++) {
                  bodyA = bodies[(col - 1) + (row * columns)];
                  bodyB = bodies[col + (row * columns)];
                  Composite.addConstraint(composite, Constraint.create(Common.extend({ bodyA: bodyA, bodyB: bodyB }, options)));
              }
  
              if (row > 0) {
                  for (col = 0; col < columns; col++) {
                      bodyA = bodies[col + ((row - 1) * columns)];
                      bodyB = bodies[col + (row * columns)];
                      Composite.addConstraint(composite, Constraint.create(Common.extend({ bodyA: bodyA, bodyB: bodyB }, options)));
  
                      if (crossBrace && col > 0) {
                          bodyC = bodies[(col - 1) + ((row - 1) * columns)];
                          Composite.addConstraint(composite, Constraint.create(Common.extend({ bodyA: bodyC, bodyB: bodyB }, options)));
                      }
  
                      if (crossBrace && col < columns - 1) {
                          bodyC = bodies[(col + 1) + ((row - 1) * columns)];
                          Composite.addConstraint(composite, Constraint.create(Common.extend({ bodyA: bodyC, bodyB: bodyB }, options)));
                      }
                  }
              }
          }
  
          composite.label += ' Mesh';
          
          return composite;
      };
      
      /**
       * Create a new composite containing bodies created in the callback in a pyramid arrangement.
       * This function uses the body's bounds to prevent overlaps.
       * @method pyramid
       * @param {number} xx
       * @param {number} yy
       * @param {number} columns
       * @param {number} rows
       * @param {number} columnGap
       * @param {number} rowGap
       * @param {function} callback
       * @return {composite} A new composite containing objects created in the callback
       */
      Composites.pyramid = function(xx, yy, columns, rows, columnGap, rowGap, callback) {
          return Composites.stack(xx, yy, columns, rows, columnGap, rowGap, function(x, y, column, row, lastBody, i) {
              var actualRows = Math.min(rows, Math.ceil(columns / 2)),
                  lastBodyWidth = lastBody ? lastBody.bounds.max.x - lastBody.bounds.min.x : 0;
              
              if (row > actualRows)
                  return;
              
              // reverse row order
              row = actualRows - row;
              
              var start = row,
                  end = columns - 1 - row;
  
              if (column < start || column > end)
                  return;
              
              // retroactively fix the first body's position, since width was unknown
              if (i === 1) {
                  Body.translate(lastBody, { x: (column + (columns % 2 === 1 ? 1 : -1)) * lastBodyWidth, y: 0 });
              }
  
              var xOffset = lastBody ? column * lastBodyWidth : 0;
              
              return callback(xx + xOffset + column * columnGap, y, column, row, lastBody, i);
          });
      };
  
      /**
       * Creates a composite with a Newton's Cradle setup of bodies and constraints.
       * @method newtonsCradle
       * @param {number} xx
       * @param {number} yy
       * @param {number} number
       * @param {number} size
       * @param {number} length
       * @return {composite} A new composite newtonsCradle body
       */
      Composites.newtonsCradle = function(xx, yy, number, size, length) {
          var newtonsCradle = Composite.create({ label: 'Newtons Cradle' });
  
          for (var i = 0; i < number; i++) {
              var separation = 1.9,
                  circle = Bodies.circle(xx + i * (size * separation), yy + length, size, 
                              { inertia: Infinity, restitution: 1, friction: 0, frictionAir: 0.0001, slop: 1 }),
                  constraint = Constraint.create({ pointA: { x: xx + i * (size * separation), y: yy }, bodyB: circle });
  
              Composite.addBody(newtonsCradle, circle);
              Composite.addConstraint(newtonsCradle, constraint);
          }
  
          return newtonsCradle;
      };
      
      /**
       * Creates a composite with simple car setup of bodies and constraints.
       * @method car
       * @param {number} xx
       * @param {number} yy
       * @param {number} width
       * @param {number} height
       * @param {number} wheelSize
       * @return {composite} A new composite car body
       */
      Composites.car = function(xx, yy, width, height, wheelSize) {
          var group = Body.nextGroup(true),
              wheelBase = -20,
              wheelAOffset = -width * 0.5 + wheelBase,
              wheelBOffset = width * 0.5 - wheelBase,
              wheelYOffset = 0;
      
          var car = Composite.create({ label: 'Car' }),
              body = Bodies.trapezoid(xx, yy, width, height, 0.3, { 
                  collisionFilter: {
                      group: group
                  },
                  friction: 0.01,
                  chamfer: {
                      radius: 10
                  }
              });
      
          var wheelA = Bodies.circle(xx + wheelAOffset, yy + wheelYOffset, wheelSize, { 
              collisionFilter: {
                  group: group
              },
              friction: 0.8,
              density: 0.01
          });
                      
          var wheelB = Bodies.circle(xx + wheelBOffset, yy + wheelYOffset, wheelSize, { 
              collisionFilter: {
                  group: group
              },
              friction: 0.8,
              density: 0.01
          });
                      
          var axelA = Constraint.create({
              bodyA: body,
              pointA: { x: wheelAOffset, y: wheelYOffset },
              bodyB: wheelA,
              stiffness: 0.2
          });
                          
          var axelB = Constraint.create({
              bodyA: body,
              pointA: { x: wheelBOffset, y: wheelYOffset },
              bodyB: wheelB,
              stiffness: 0.2
          });
          
          Composite.addBody(car, body);
          Composite.addBody(car, wheelA);
          Composite.addBody(car, wheelB);
          Composite.addConstraint(car, axelA);
          Composite.addConstraint(car, axelB);
  
          return car;
      };
  
      /**
       * Creates a simple soft body like object.
       * @method softBody
       * @param {number} xx
       * @param {number} yy
       * @param {number} columns
       * @param {number} rows
       * @param {number} columnGap
       * @param {number} rowGap
       * @param {boolean} crossBrace
       * @param {number} particleRadius
       * @param {} particleOptions
       * @param {} constraintOptions
       * @return {composite} A new composite softBody
       */
      Composites.softBody = function(xx, yy, columns, rows, columnGap, rowGap, crossBrace, particleRadius, particleOptions, constraintOptions) {
          particleOptions = Common.extend({ inertia: Infinity }, particleOptions);
          constraintOptions = Common.extend({ stiffness: 0.4 }, constraintOptions);
  
          var softBody = Composites.stack(xx, yy, columns, rows, columnGap, rowGap, function(x, y) {
              return Bodies.circle(x, y, particleRadius, particleOptions);
          });
  
          Composites.mesh(softBody, columns, rows, crossBrace, constraintOptions);
  
          softBody.label = 'Soft Body';
  
          return softBody;
      };
  
  })();
  
  },{"../body/Body":1,"../body/Composite":2,"../constraint/Constraint":12,"../core/Common":14,"./Bodies":21}],23:[function(require,module,exports){
  /**
  * The `Matter.Axes` module contains methods for creating and manipulating sets of axes.
  *
  * @class Axes
  */
  
  var Axes = {};
  
  module.exports = Axes;
  
  var Vector = require('../geometry/Vector');
  var Common = require('../core/Common');
  
  (function() {
  
      /**
       * Creates a new set of axes from the given vertices.
       * @method fromVertices
       * @param {vertices} vertices
       * @return {axes} A new axes from the given vertices
       */
      Axes.fromVertices = function(vertices) {
          var axes = {};
  
          // find the unique axes, using edge normal gradients
          for (var i = 0; i < vertices.length; i++) {
              var j = (i + 1) % vertices.length, 
                  normal = Vector.normalise({ 
                      x: vertices[j].y - vertices[i].y, 
                      y: vertices[i].x - vertices[j].x
                  }),
                  gradient = (normal.y === 0) ? Infinity : (normal.x / normal.y);
              
              // limit precision
              gradient = gradient.toFixed(3).toString();
              axes[gradient] = normal;
          }
  
          return Common.values(axes);
      };
  
      /**
       * Rotates a set of axes by the given angle.
       * @method rotate
       * @param {axes} axes
       * @param {number} angle
       */
      Axes.rotate = function(axes, angle) {
          if (angle === 0)
              return;
          
          var cos = Math.cos(angle),
              sin = Math.sin(angle);
  
          for (var i = 0; i < axes.length; i++) {
              var axis = axes[i],
                  xx;
              xx = axis.x * cos - axis.y * sin;
              axis.y = axis.x * sin + axis.y * cos;
              axis.x = xx;
          }
      };
  
  })();
  
  },{"../core/Common":14,"../geometry/Vector":26}],24:[function(require,module,exports){
  /**
  * The `Matter.Bounds` module contains methods for creating and manipulating axis-aligned bounding boxes (AABB).
  *
  * @class Bounds
  */
  
  var Bounds = {};
  
  module.exports = Bounds;
  
  (function() {
  
      /**
       * Creates a new axis-aligned bounding box (AABB) for the given vertices.
       * @method create
       * @param {vertices} vertices
       * @return {bounds} A new bounds object
       */
      Bounds.create = function(vertices) {
          var bounds = { 
              min: { x: 0, y: 0 }, 
              max: { x: 0, y: 0 }
          };
  
          if (vertices)
              Bounds.update(bounds, vertices);
          
          return bounds;
      };
  
      /**
       * Updates bounds using the given vertices and extends the bounds given a velocity.
       * @method update
       * @param {bounds} bounds
       * @param {vertices} vertices
       * @param {vector} velocity
       */
      Bounds.update = function(bounds, vertices, velocity) {
          bounds.min.x = Number.MAX_VALUE;
          bounds.max.x = Number.MIN_VALUE;
          bounds.min.y = Number.MAX_VALUE;
          bounds.max.y = Number.MIN_VALUE;
  
          for (var i = 0; i < vertices.length; i++) {
              var vertex = vertices[i];
              if (vertex.x > bounds.max.x) bounds.max.x = vertex.x;
              if (vertex.x < bounds.min.x) bounds.min.x = vertex.x;
              if (vertex.y > bounds.max.y) bounds.max.y = vertex.y;
              if (vertex.y < bounds.min.y) bounds.min.y = vertex.y;
          }
          
          if (velocity) {
              if (velocity.x > 0) {
                  bounds.max.x += velocity.x;
              } else {
                  bounds.min.x += velocity.x;
              }
              
              if (velocity.y > 0) {
                  bounds.max.y += velocity.y;
              } else {
                  bounds.min.y += velocity.y;
              }
          }
      };
  
      /**
       * Returns true if the bounds contains the given point.
       * @method contains
       * @param {bounds} bounds
       * @param {vector} point
       * @return {boolean} True if the bounds contain the point, otherwise false
       */
      Bounds.contains = function(bounds, point) {
          return point.x >= bounds.min.x && point.x <= bounds.max.x 
                 && point.y >= bounds.min.y && point.y <= bounds.max.y;
      };
  
      /**
       * Returns true if the two bounds intersect.
       * @method overlaps
       * @param {bounds} boundsA
       * @param {bounds} boundsB
       * @return {boolean} True if the bounds overlap, otherwise false
       */
      Bounds.overlaps = function(boundsA, boundsB) {
          return (boundsA.min.x <= boundsB.max.x && boundsA.max.x >= boundsB.min.x
                  && boundsA.max.y >= boundsB.min.y && boundsA.min.y <= boundsB.max.y);
      };
  
      /**
       * Translates the bounds by the given vector.
       * @method translate
       * @param {bounds} bounds
       * @param {vector} vector
       */
      Bounds.translate = function(bounds, vector) {
          bounds.min.x += vector.x;
          bounds.max.x += vector.x;
          bounds.min.y += vector.y;
          bounds.max.y += vector.y;
      };
  
      /**
       * Shifts the bounds to the given position.
       * @method shift
       * @param {bounds} bounds
       * @param {vector} position
       */
      Bounds.shift = function(bounds, position) {
          var deltaX = bounds.max.x - bounds.min.x,
              deltaY = bounds.max.y - bounds.min.y;
              
          bounds.min.x = position.x;
          bounds.max.x = position.x + deltaX;
          bounds.min.y = position.y;
          bounds.max.y = position.y + deltaY;
      };
      
  })();
  
  },{}],25:[function(require,module,exports){
  /**
  * The `Matter.Svg` module contains methods for converting SVG images into an array of vector points.
  *
  * See the included usage [examples](https://github.com/liabru/matter-js/tree/master/examples).
  *
  * @class Svg
  */
  
  var Svg = {};
  
  module.exports = Svg;
  
  var Bounds = require('../geometry/Bounds');
  
  (function() {
  
      /**
       * Converts an SVG path into an array of vector points.
       * If the input path forms a concave shape, you must decompose the result into convex parts before use.
       * See `Bodies.fromVertices` which provides support for this.
       * Note that this function is not guaranteed to support complex paths (such as those with holes).
       * @method pathToVertices
       * @param {SVGPathElement} path
       * @param {Number} [sampleLength=15]
       * @return {Vector[]} points
       */
      Svg.pathToVertices = function(path, sampleLength) {
          // https://github.com/wout/svg.topoly.js/blob/master/svg.topoly.js
          var i, il, total, point, segment, segments, 
              segmentsQueue, lastSegment, 
              lastPoint, segmentIndex, points = [],
              lx, ly, length = 0, x = 0, y = 0;
  
          sampleLength = sampleLength || 15;
  
          var addPoint = function(px, py, pathSegType) {
              // all odd-numbered path types are relative except PATHSEG_CLOSEPATH (1)
              var isRelative = pathSegType % 2 === 1 && pathSegType > 1;
  
              // when the last point doesn't equal the current point add the current point
              if (!lastPoint || px != lastPoint.x || py != lastPoint.y) {
                  if (lastPoint && isRelative) {
                      lx = lastPoint.x;
                      ly = lastPoint.y;
                  } else {
                      lx = 0;
                      ly = 0;
                  }
  
                  var point = {
                      x: lx + px,
                      y: ly + py
                  };
  
                  // set last point
                  if (isRelative || !lastPoint) {
                      lastPoint = point;
                  }
  
                  points.push(point);
  
                  x = lx + px;
                  y = ly + py;
              }
          };
  
          var addSegmentPoint = function(segment) {
              var segType = segment.pathSegTypeAsLetter.toUpperCase();
  
              // skip path ends
              if (segType === 'Z') 
                  return;
  
              // map segment to x and y
              switch (segType) {
  
              case 'M':
              case 'L':
              case 'T':
              case 'C':
              case 'S':
              case 'Q':
                  x = segment.x;
                  y = segment.y;
                  break;
              case 'H':
                  x = segment.x;
                  break;
              case 'V':
                  y = segment.y;
                  break;
              }
  
              addPoint(x, y, segment.pathSegType);
          };
  
          // ensure path is absolute
          _svgPathToAbsolute(path);
  
          // get total length
          total = path.getTotalLength();
  
          // queue segments
          segments = [];
          for (i = 0; i < path.pathSegList.numberOfItems; i += 1)
              segments.push(path.pathSegList.getItem(i));
  
          segmentsQueue = segments.concat();
  
          // sample through path
          while (length < total) {
              // get segment at position
              segmentIndex = path.getPathSegAtLength(length);
              segment = segments[segmentIndex];
  
              // new segment
              if (segment != lastSegment) {
                  while (segmentsQueue.length && segmentsQueue[0] != segment)
                      addSegmentPoint(segmentsQueue.shift());
  
                  lastSegment = segment;
              }
  
              // add points in between when curving
              // TODO: adaptive sampling
              switch (segment.pathSegTypeAsLetter.toUpperCase()) {
  
              case 'C':
              case 'T':
              case 'S':
              case 'Q':
              case 'A':
                  point = path.getPointAtLength(length);
                  addPoint(point.x, point.y, 0);
                  break;
  
              }
  
              // increment by sample value
              length += sampleLength;
          }
  
          // add remaining segments not passed by sampling
          for (i = 0, il = segmentsQueue.length; i < il; ++i)
              addSegmentPoint(segmentsQueue[i]);
  
          return points;
      };
  
      var _svgPathToAbsolute = function(path) {
          // http://phrogz.net/convert-svg-path-to-all-absolute-commands
          var x0, y0, x1, y1, x2, y2, segs = path.pathSegList,
              x = 0, y = 0, len = segs.numberOfItems;
  
          for (var i = 0; i < len; ++i) {
              var seg = segs.getItem(i),
                  segType = seg.pathSegTypeAsLetter;
  
              if (/[MLHVCSQTA]/.test(segType)) {
                  if ('x' in seg) x = seg.x;
                  if ('y' in seg) y = seg.y;
              } else {
                  if ('x1' in seg) x1 = x + seg.x1;
                  if ('x2' in seg) x2 = x + seg.x2;
                  if ('y1' in seg) y1 = y + seg.y1;
                  if ('y2' in seg) y2 = y + seg.y2;
                  if ('x' in seg) x += seg.x;
                  if ('y' in seg) y += seg.y;
  
                  switch (segType) {
  
                  case 'm':
                      segs.replaceItem(path.createSVGPathSegMovetoAbs(x, y), i);
                      break;
                  case 'l':
                      segs.replaceItem(path.createSVGPathSegLinetoAbs(x, y), i);
                      break;
                  case 'h':
                      segs.replaceItem(path.createSVGPathSegLinetoHorizontalAbs(x), i);
                      break;
                  case 'v':
                      segs.replaceItem(path.createSVGPathSegLinetoVerticalAbs(y), i);
                      break;
                  case 'c':
                      segs.replaceItem(path.createSVGPathSegCurvetoCubicAbs(x, y, x1, y1, x2, y2), i);
                      break;
                  case 's':
                      segs.replaceItem(path.createSVGPathSegCurvetoCubicSmoothAbs(x, y, x2, y2), i);
                      break;
                  case 'q':
                      segs.replaceItem(path.createSVGPathSegCurvetoQuadraticAbs(x, y, x1, y1), i);
                      break;
                  case 't':
                      segs.replaceItem(path.createSVGPathSegCurvetoQuadraticSmoothAbs(x, y), i);
                      break;
                  case 'a':
                      segs.replaceItem(path.createSVGPathSegArcAbs(x, y, seg.r1, seg.r2, seg.angle, seg.largeArcFlag, seg.sweepFlag), i);
                      break;
                  case 'z':
                  case 'Z':
                      x = x0;
                      y = y0;
                      break;
  
                  }
              }
  
              if (segType == 'M' || segType == 'm') {
                  x0 = x;
                  y0 = y;
              }
          }
      };
  
  })();
  },{"../geometry/Bounds":24}],26:[function(require,module,exports){
  /**
  * The `Matter.Vector` module contains methods for creating and manipulating vectors.
  * Vectors are the basis of all the geometry related operations in the engine.
  * A `Matter.Vector` object is of the form `{ x: 0, y: 0 }`.
  *
  * See the included usage [examples](https://github.com/liabru/matter-js/tree/master/examples).
  *
  * @class Vector
  */
  
  // TODO: consider params for reusing vector objects
  
  var Vector = {};
  
  module.exports = Vector;
  
  (function() {
  
      /**
       * Creates a new vector.
       * @method create
       * @param {number} x
       * @param {number} y
       * @return {vector} A new vector
       */
      Vector.create = function(x, y) {
          return { x: x || 0, y: y || 0 };
      };
  
      /**
       * Returns a new vector with `x` and `y` copied from the given `vector`.
       * @method clone
       * @param {vector} vector
       * @return {vector} A new cloned vector
       */
      Vector.clone = function(vector) {
          return { x: vector.x, y: vector.y };
      };
  
      /**
       * Returns the magnitude (length) of a vector.
       * @method magnitude
       * @param {vector} vector
       * @return {number} The magnitude of the vector
       */
      Vector.magnitude = function(vector) {
          return Math.sqrt((vector.x * vector.x) + (vector.y * vector.y));
      };
  
      /**
       * Returns the magnitude (length) of a vector (therefore saving a `sqrt` operation).
       * @method magnitudeSquared
       * @param {vector} vector
       * @return {number} The squared magnitude of the vector
       */
      Vector.magnitudeSquared = function(vector) {
          return (vector.x * vector.x) + (vector.y * vector.y);
      };
  
      /**
       * Rotates the vector about (0, 0) by specified angle.
       * @method rotate
       * @param {vector} vector
       * @param {number} angle
       * @return {vector} A new vector rotated about (0, 0)
       */
      Vector.rotate = function(vector, angle) {
          var cos = Math.cos(angle), sin = Math.sin(angle);
          return {
              x: vector.x * cos - vector.y * sin,
              y: vector.x * sin + vector.y * cos
          };
      };
  
      /**
       * Rotates the vector about a specified point by specified angle.
       * @method rotateAbout
       * @param {vector} vector
       * @param {number} angle
       * @param {vector} point
       * @param {vector} [output]
       * @return {vector} A new vector rotated about the point
       */
      Vector.rotateAbout = function(vector, angle, point, output) {
          var cos = Math.cos(angle), sin = Math.sin(angle);
          if (!output) output = {};
          var x = point.x + ((vector.x - point.x) * cos - (vector.y - point.y) * sin);
          output.y = point.y + ((vector.x - point.x) * sin + (vector.y - point.y) * cos);
          output.x = x;
          return output;
      };
  
      /**
       * Normalises a vector (such that its magnitude is `1`).
       * @method normalise
       * @param {vector} vector
       * @return {vector} A new vector normalised
       */
      Vector.normalise = function(vector) {
          var magnitude = Vector.magnitude(vector);
          if (magnitude === 0)
              return { x: 0, y: 0 };
          return { x: vector.x / magnitude, y: vector.y / magnitude };
      };
  
      /**
       * Returns the dot-product of two vectors.
       * @method dot
       * @param {vector} vectorA
       * @param {vector} vectorB
       * @return {number} The dot product of the two vectors
       */
      Vector.dot = function(vectorA, vectorB) {
          return (vectorA.x * vectorB.x) + (vectorA.y * vectorB.y);
      };
  
      /**
       * Returns the cross-product of two vectors.
       * @method cross
       * @param {vector} vectorA
       * @param {vector} vectorB
       * @return {number} The cross product of the two vectors
       */
      Vector.cross = function(vectorA, vectorB) {
          return (vectorA.x * vectorB.y) - (vectorA.y * vectorB.x);
      };
  
      /**
       * Returns the cross-product of three vectors.
       * @method cross3
       * @param {vector} vectorA
       * @param {vector} vectorB
       * @param {vector} vectorC
       * @return {number} The cross product of the three vectors
       */
      Vector.cross3 = function(vectorA, vectorB, vectorC) {
          return (vectorB.x - vectorA.x) * (vectorC.y - vectorA.y) - (vectorB.y - vectorA.y) * (vectorC.x - vectorA.x);
      };
  
      /**
       * Adds the two vectors.
       * @method add
       * @param {vector} vectorA
       * @param {vector} vectorB
       * @param {vector} [output]
       * @return {vector} A new vector of vectorA and vectorB added
       */
      Vector.add = function(vectorA, vectorB, output) {
          if (!output) output = {};
          output.x = vectorA.x + vectorB.x;
          output.y = vectorA.y + vectorB.y;
          return output;
      };
  
      /**
       * Subtracts the two vectors.
       * @method sub
       * @param {vector} vectorA
       * @param {vector} vectorB
       * @param {vector} [output]
       * @return {vector} A new vector of vectorA and vectorB subtracted
       */
      Vector.sub = function(vectorA, vectorB, output) {
          if (!output) output = {};
          output.x = vectorA.x - vectorB.x;
          output.y = vectorA.y - vectorB.y;
          return output;
      };
  
      /**
       * Multiplies a vector and a scalar.
       * @method mult
       * @param {vector} vector
       * @param {number} scalar
       * @return {vector} A new vector multiplied by scalar
       */
      Vector.mult = function(vector, scalar) {
          return { x: vector.x * scalar, y: vector.y * scalar };
      };
  
      /**
       * Divides a vector and a scalar.
       * @method div
       * @param {vector} vector
       * @param {number} scalar
       * @return {vector} A new vector divided by scalar
       */
      Vector.div = function(vector, scalar) {
          return { x: vector.x / scalar, y: vector.y / scalar };
      };
  
      /**
       * Returns the perpendicular vector. Set `negate` to true for the perpendicular in the opposite direction.
       * @method perp
       * @param {vector} vector
       * @param {bool} [negate=false]
       * @return {vector} The perpendicular vector
       */
      Vector.perp = function(vector, negate) {
          negate = negate === true ? -1 : 1;
          return { x: negate * -vector.y, y: negate * vector.x };
      };
  
      /**
       * Negates both components of a vector such that it points in the opposite direction.
       * @method neg
       * @param {vector} vector
       * @return {vector} The negated vector
       */
      Vector.neg = function(vector) {
          return { x: -vector.x, y: -vector.y };
      };
  
      /**
       * Returns the angle in radians between the two vectors relative to the x-axis.
       * @method angle
       * @param {vector} vectorA
       * @param {vector} vectorB
       * @return {number} The angle in radians
       */
      Vector.angle = function(vectorA, vectorB) {
          return Math.atan2(vectorB.y - vectorA.y, vectorB.x - vectorA.x);
      };
  
      /**
       * Temporary vector pool (not thread-safe).
       * @property _temp
       * @type {vector[]}
       * @private
       */
      Vector._temp = [Vector.create(), Vector.create(), 
                      Vector.create(), Vector.create(), 
                      Vector.create(), Vector.create()];
  
  })();
  },{}],27:[function(require,module,exports){
  /**
  * The `Matter.Vertices` module contains methods for creating and manipulating sets of vertices.
  * A set of vertices is an array of `Matter.Vector` with additional indexing properties inserted by `Vertices.create`.
  * A `Matter.Body` maintains a set of vertices to represent the shape of the object (its convex hull).
  *
  * See the included usage [examples](https://github.com/liabru/matter-js/tree/master/examples).
  *
  * @class Vertices
  */
  
  var Vertices = {};
  
  module.exports = Vertices;
  
  var Vector = require('../geometry/Vector');
  var Common = require('../core/Common');
  
  (function() {
  
      /**
       * Creates a new set of `Matter.Body` compatible vertices.
       * The `points` argument accepts an array of `Matter.Vector` points orientated around the origin `(0, 0)`, for example:
       *
       *     [{ x: 0, y: 0 }, { x: 25, y: 50 }, { x: 50, y: 0 }]
       *
       * The `Vertices.create` method returns a new array of vertices, which are similar to Matter.Vector objects,
       * but with some additional references required for efficient collision detection routines.
       *
       * Note that the `body` argument is not optional, a `Matter.Body` reference must be provided.
       *
       * @method create
       * @param {vector[]} points
       * @param {body} body
       */
      Vertices.create = function(points, body) {
          var vertices = [];
  
          for (var i = 0; i < points.length; i++) {
              var point = points[i],
                  vertex = {
                      x: point.x,
                      y: point.y,
                      index: i,
                      body: body,
                      isInternal: false
                  };
  
              vertices.push(vertex);
          }
  
          return vertices;
      };
  
      /**
       * Parses a string containing ordered x y pairs separated by spaces (and optionally commas), 
       * into a `Matter.Vertices` object for the given `Matter.Body`.
       * For parsing SVG paths, see `Svg.pathToVertices`.
       * @method fromPath
       * @param {string} path
       * @param {body} body
       * @return {vertices} vertices
       */
      Vertices.fromPath = function(path, body) {
          var pathPattern = /L?\s*([\-\d\.e]+)[\s,]*([\-\d\.e]+)*/ig,
              points = [];
  
          path.replace(pathPattern, function(match, x, y) {
              points.push({ x: parseFloat(x), y: parseFloat(y) });
          });
  
          return Vertices.create(points, body);
      };
  
      /**
       * Returns the centre (centroid) of the set of vertices.
       * @method centre
       * @param {vertices} vertices
       * @return {vector} The centre point
       */
      Vertices.centre = function(vertices) {
          var area = Vertices.area(vertices, true),
              centre = { x: 0, y: 0 },
              cross,
              temp,
              j;
  
          for (var i = 0; i < vertices.length; i++) {
              j = (i + 1) % vertices.length;
              cross = Vector.cross(vertices[i], vertices[j]);
              temp = Vector.mult(Vector.add(vertices[i], vertices[j]), cross);
              centre = Vector.add(centre, temp);
          }
  
          return Vector.div(centre, 6 * area);
      };
  
      /**
       * Returns the average (mean) of the set of vertices.
       * @method mean
       * @param {vertices} vertices
       * @return {vector} The average point
       */
      Vertices.mean = function(vertices) {
          var average = { x: 0, y: 0 };
  
          for (var i = 0; i < vertices.length; i++) {
              average.x += vertices[i].x;
              average.y += vertices[i].y;
          }
  
          return Vector.div(average, vertices.length);
      };
  
      /**
       * Returns the area of the set of vertices.
       * @method area
       * @param {vertices} vertices
       * @param {bool} signed
       * @return {number} The area
       */
      Vertices.area = function(vertices, signed) {
          var area = 0,
              j = vertices.length - 1;
  
          for (var i = 0; i < vertices.length; i++) {
              area += (vertices[j].x - vertices[i].x) * (vertices[j].y + vertices[i].y);
              j = i;
          }
  
          if (signed)
              return area / 2;
  
          return Math.abs(area) / 2;
      };
  
      /**
       * Returns the moment of inertia (second moment of area) of the set of vertices given the total mass.
       * @method inertia
       * @param {vertices} vertices
       * @param {number} mass
       * @return {number} The polygon's moment of inertia
       */
      Vertices.inertia = function(vertices, mass) {
          var numerator = 0,
              denominator = 0,
              v = vertices,
              cross,
              j;
  
          // find the polygon's moment of inertia, using second moment of area
          // http://www.physicsforums.com/showthread.php?t=25293
          for (var n = 0; n < v.length; n++) {
              j = (n + 1) % v.length;
              cross = Math.abs(Vector.cross(v[j], v[n]));
              numerator += cross * (Vector.dot(v[j], v[j]) + Vector.dot(v[j], v[n]) + Vector.dot(v[n], v[n]));
              denominator += cross;
          }
  
          return (mass / 6) * (numerator / denominator);
      };
  
      /**
       * Translates the set of vertices in-place.
       * @method translate
       * @param {vertices} vertices
       * @param {vector} vector
       * @param {number} scalar
       */
      Vertices.translate = function(vertices, vector, scalar) {
          var i;
          if (scalar) {
              for (i = 0; i < vertices.length; i++) {
                  vertices[i].x += vector.x * scalar;
                  vertices[i].y += vector.y * scalar;
              }
          } else {
              for (i = 0; i < vertices.length; i++) {
                  vertices[i].x += vector.x;
                  vertices[i].y += vector.y;
              }
          }
  
          return vertices;
      };
  
      /**
       * Rotates the set of vertices in-place.
       * @method rotate
       * @param {vertices} vertices
       * @param {number} angle
       * @param {vector} point
       */
      Vertices.rotate = function(vertices, angle, point) {
          if (angle === 0)
              return;
  
          var cos = Math.cos(angle),
              sin = Math.sin(angle);
  
          for (var i = 0; i < vertices.length; i++) {
              var vertice = vertices[i],
                  dx = vertice.x - point.x,
                  dy = vertice.y - point.y;
                  
              vertice.x = point.x + (dx * cos - dy * sin);
              vertice.y = point.y + (dx * sin + dy * cos);
          }
  
          return vertices;
      };
  
      /**
       * Returns `true` if the `point` is inside the set of `vertices`.
       * @method contains
       * @param {vertices} vertices
       * @param {vector} point
       * @return {boolean} True if the vertices contains point, otherwise false
       */
      Vertices.contains = function(vertices, point) {
          for (var i = 0; i < vertices.length; i++) {
              var vertice = vertices[i],
                  nextVertice = vertices[(i + 1) % vertices.length];
              if ((point.x - vertice.x) * (nextVertice.y - vertice.y) + (point.y - vertice.y) * (vertice.x - nextVertice.x) > 0) {
                  return false;
              }
          }
  
          return true;
      };
  
      /**
       * Scales the vertices from a point (default is centre) in-place.
       * @method scale
       * @param {vertices} vertices
       * @param {number} scaleX
       * @param {number} scaleY
       * @param {vector} point
       */
      Vertices.scale = function(vertices, scaleX, scaleY, point) {
          if (scaleX === 1 && scaleY === 1)
              return vertices;
  
          point = point || Vertices.centre(vertices);
  
          var vertex,
              delta;
  
          for (var i = 0; i < vertices.length; i++) {
              vertex = vertices[i];
              delta = Vector.sub(vertex, point);
              vertices[i].x = point.x + delta.x * scaleX;
              vertices[i].y = point.y + delta.y * scaleY;
          }
  
          return vertices;
      };
  
      /**
       * Chamfers a set of vertices by giving them rounded corners, returns a new set of vertices.
       * The radius parameter is a single number or an array to specify the radius for each vertex.
       * @method chamfer
       * @param {vertices} vertices
       * @param {number[]} radius
       * @param {number} quality
       * @param {number} qualityMin
       * @param {number} qualityMax
       */
      Vertices.chamfer = function(vertices, radius, quality, qualityMin, qualityMax) {
          radius = radius || [8];
  
          if (!radius.length)
              radius = [radius];
  
          // quality defaults to -1, which is auto
          quality = (typeof quality !== 'undefined') ? quality : -1;
          qualityMin = qualityMin || 2;
          qualityMax = qualityMax || 14;
  
          var newVertices = [];
  
          for (var i = 0; i < vertices.length; i++) {
              var prevVertex = vertices[i - 1 >= 0 ? i - 1 : vertices.length - 1],
                  vertex = vertices[i],
                  nextVertex = vertices[(i + 1) % vertices.length],
                  currentRadius = radius[i < radius.length ? i : radius.length - 1];
  
              if (currentRadius === 0) {
                  newVertices.push(vertex);
                  continue;
              }
  
              var prevNormal = Vector.normalise({ 
                  x: vertex.y - prevVertex.y, 
                  y: prevVertex.x - vertex.x
              });
  
              var nextNormal = Vector.normalise({ 
                  x: nextVertex.y - vertex.y, 
                  y: vertex.x - nextVertex.x
              });
  
              var diagonalRadius = Math.sqrt(2 * Math.pow(currentRadius, 2)),
                  radiusVector = Vector.mult(Common.clone(prevNormal), currentRadius),
                  midNormal = Vector.normalise(Vector.mult(Vector.add(prevNormal, nextNormal), 0.5)),
                  scaledVertex = Vector.sub(vertex, Vector.mult(midNormal, diagonalRadius));
  
              var precision = quality;
  
              if (quality === -1) {
                  // automatically decide precision
                  precision = Math.pow(currentRadius, 0.32) * 1.75;
              }
  
              precision = Common.clamp(precision, qualityMin, qualityMax);
  
              // use an even value for precision, more likely to reduce axes by using symmetry
              if (precision % 2 === 1)
                  precision += 1;
  
              var alpha = Math.acos(Vector.dot(prevNormal, nextNormal)),
                  theta = alpha / precision;
  
              for (var j = 0; j < precision; j++) {
                  newVertices.push(Vector.add(Vector.rotate(radiusVector, theta * j), scaledVertex));
              }
          }
  
          return newVertices;
      };
  
      /**
       * Sorts the input vertices into clockwise order in place.
       * @method clockwiseSort
       * @param {vertices} vertices
       * @return {vertices} vertices
       */
      Vertices.clockwiseSort = function(vertices) {
          var centre = Vertices.mean(vertices);
  
          vertices.sort(function(vertexA, vertexB) {
              return Vector.angle(centre, vertexA) - Vector.angle(centre, vertexB);
          });
  
          return vertices;
      };
  
      /**
       * Returns true if the vertices form a convex shape (vertices must be in clockwise order).
       * @method isConvex
       * @param {vertices} vertices
       * @return {bool} `true` if the `vertices` are convex, `false` if not (or `null` if not computable).
       */
      Vertices.isConvex = function(vertices) {
          // http://paulbourke.net/geometry/polygonmesh/
  
          var flag = 0,
              n = vertices.length,
              i,
              j,
              k,
              z;
  
          if (n < 3)
              return null;
  
          for (i = 0; i < n; i++) {
              j = (i + 1) % n;
              k = (i + 2) % n;
              z = (vertices[j].x - vertices[i].x) * (vertices[k].y - vertices[j].y);
              z -= (vertices[j].y - vertices[i].y) * (vertices[k].x - vertices[j].x);
  
              if (z < 0) {
                  flag |= 1;
              } else if (z > 0) {
                  flag |= 2;
              }
  
              if (flag === 3) {
                  return false;
              }
          }
  
          if (flag !== 0){
              return true;
          } else {
              return null;
          }
      };
  
      /**
       * Returns the convex hull of the input vertices as a new array of points.
       * @method hull
       * @param {vertices} vertices
       * @return [vertex] vertices
       */
      Vertices.hull = function(vertices) {
          // http://en.wikibooks.org/wiki/Algorithm_Implementation/Geometry/Convex_hull/Monotone_chain
  
          var upper = [],
              lower = [], 
              vertex,
              i;
  
          // sort vertices on x-axis (y-axis for ties)
          vertices = vertices.slice(0);
          vertices.sort(function(vertexA, vertexB) {
              var dx = vertexA.x - vertexB.x;
              return dx !== 0 ? dx : vertexA.y - vertexB.y;
          });
  
          // build lower hull
          for (i = 0; i < vertices.length; i++) {
              vertex = vertices[i];
  
              while (lower.length >= 2 
                     && Vector.cross3(lower[lower.length - 2], lower[lower.length - 1], vertex) <= 0) {
                  lower.pop();
              }
  
              lower.push(vertex);
          }
  
          // build upper hull
          for (i = vertices.length - 1; i >= 0; i--) {
              vertex = vertices[i];
  
              while (upper.length >= 2 
                     && Vector.cross3(upper[upper.length - 2], upper[upper.length - 1], vertex) <= 0) {
                  upper.pop();
              }
  
              upper.push(vertex);
          }
  
          // concatenation of the lower and upper hulls gives the convex hull
          // omit last points because they are repeated at the beginning of the other list
          upper.pop();
          lower.pop();
  
          return upper.concat(lower);
      };
  
  })();
  
  },{"../core/Common":14,"../geometry/Vector":26}],28:[function(require,module,exports){
  var Matter = module.exports = {};
  Matter.version = 'master';
  
  Matter.Body = require('../body/Body');
  Matter.Composite = require('../body/Composite');
  Matter.World = require('../body/World');
  
  Matter.Contact = require('../collision/Contact');
  Matter.Detector = require('../collision/Detector');
  Matter.Grid = require('../collision/Grid');
  Matter.Pairs = require('../collision/Pairs');
  Matter.Pair = require('../collision/Pair');
  Matter.Query = require('../collision/Query');
  Matter.Resolver = require('../collision/Resolver');
  Matter.SAT = require('../collision/SAT');
  
  Matter.Constraint = require('../constraint/Constraint');
  Matter.MouseConstraint = require('../constraint/MouseConstraint');
  
  Matter.Common = require('../core/Common');
  Matter.Engine = require('../core/Engine');
  Matter.Events = require('../core/Events');
  Matter.Mouse = require('../core/Mouse');
  Matter.Runner = require('../core/Runner');
  Matter.Sleeping = require('../core/Sleeping');
  
  
  Matter.Bodies = require('../factory/Bodies');
  Matter.Composites = require('../factory/Composites');
  
  Matter.Axes = require('../geometry/Axes');
  Matter.Bounds = require('../geometry/Bounds');
  Matter.Svg = require('../geometry/Svg');
  Matter.Vector = require('../geometry/Vector');
  Matter.Vertices = require('../geometry/Vertices');
  
  Matter.Render = require('../render/Render');
  Matter.RenderPixi = require('../render/RenderPixi');
  
  // aliases
  
  Matter.World.add = Matter.Composite.add;
  Matter.World.remove = Matter.Composite.remove;
  Matter.World.addComposite = Matter.Composite.addComposite;
  Matter.World.addBody = Matter.Composite.addBody;
  Matter.World.addConstraint = Matter.Composite.addConstraint;
  Matter.World.clear = Matter.Composite.clear;
  Matter.Engine.run = Matter.Runner.run;
  
  },{"../body/Body":1,"../body/Composite":2,"../body/World":3,"../collision/Contact":4,"../collision/Detector":5,"../collision/Grid":6,"../collision/Pair":7,"../collision/Pairs":8,"../collision/Query":9,"../collision/Resolver":10,"../collision/SAT":11,"../constraint/Constraint":12,"../constraint/MouseConstraint":13,"../core/Common":14,"../core/Engine":15,"../core/Events":16,"../core/Metrics":17,"../core/Mouse":18,"../core/Runner":19,"../core/Sleeping":20,"../factory/Bodies":21,"../factory/Composites":22,"../geometry/Axes":23,"../geometry/Bounds":24,"../geometry/Svg":25,"../geometry/Vector":26,"../geometry/Vertices":27,"../render/Render":29,"../render/RenderPixi":30}],29:[function(require,module,exports){
  /**
  * The `Matter.Render` module is the default `render.controller` used by a `Matter.Engine`.
  * This renderer is HTML5 canvas based and supports a number of drawing options including sprites and viewports.
  *
  * It is possible develop a custom renderer module based on `Matter.Render` and pass an instance of it to `Engine.create` via `options.render`.
  * A minimal custom renderer object must define at least three functions: `create`, `clear` and `world` (see `Matter.Render`).
  *
  * See also `Matter.RenderPixi` for an alternate WebGL, scene-graph based renderer.
  *
  * @class Render
  */
  
  var Render = {};
  
  module.exports = Render;
  
  var Common = require('../core/Common');
  var Composite = require('../body/Composite');
  var Bounds = require('../geometry/Bounds');
  var Events = require('../core/Events');
  var Grid = require('../collision/Grid');
  var Vector = require('../geometry/Vector');
  
  (function() {
      
      /**
       * Creates a new renderer. The options parameter is an object that specifies any properties you wish to override the defaults.
       * All properties have default values, and many are pre-calculated automatically based on other properties.
       * See the properties section below for detailed information on what you can pass via the `options` object.
       * @method create
       * @param {object} [options]
       * @return {render} A new renderer
       */
      Render.create = function(options) {
          var defaults = {
              controller: Render,
              element: null,
              canvas: null,
              mouse: null,
              options: {
                  width: 800,
                  height: 600,
                  pixelRatio: 1,
                  background: '#fafafa',
                  wireframeBackground: '#222',
                  hasBounds: false,
                  enabled: true,
                  wireframes: true,
                  showSleeping: true,
                  showDebug: false,
                  showBroadphase: false,
                  showBounds: false,
                  showVelocity: false,
                  showCollisions: false,
                  showSeparations: false,
                  showAxes: false,
                  showPositions: false,
                  showAngleIndicator: false,
                  showIds: false,
                  showShadows: false,
                  showVertexNumbers: false,
                  showConvexHulls: false,
                  showInternalEdges: false,
                  showMousePosition: false
              }
          };
  
          var render = Common.extend(defaults, options);
  
          if (render.canvas) {
              render.canvas.width = render.options.width || render.canvas.width;
              render.canvas.height = render.options.height || render.canvas.height;
          }
  
          render.canvas = render.canvas || _createCanvas(render.options.width, render.options.height);
          render.context = render.canvas.getContext('2d');
          render.textures = {};
  
          render.bounds = render.bounds || { 
              min: { 
                  x: 0,
                  y: 0
              }, 
              max: { 
                  x: render.canvas.width,
                  y: render.canvas.height
              }
          };
  
          if (render.options.pixelRatio !== 1) {
              Render.setPixelRatio(render, render.options.pixelRatio);
          }
  
          if (Common.isElement(render.element)) {
              render.element.appendChild(render.canvas);
          } else {
              Common.log('Render.create: options.element was undefined, render.canvas was created but not appended', 'warn');
          }
  
          return render;
      };
  
      /**
       * Sets the pixel ratio of the renderer and updates the canvas.
       * To automatically detect the correct ratio, pass the string `'auto'` for `pixelRatio`.
       * @method setPixelRatio
       * @param {render} render
       * @param {number} pixelRatio
       */
      Render.setPixelRatio = function(render, pixelRatio) {
          var options = render.options,
              canvas = render.canvas;
  
          if (pixelRatio === 'auto') {
              pixelRatio = _getPixelRatio(canvas);
          }
  
          options.pixelRatio = pixelRatio;
          canvas.setAttribute('data-pixel-ratio', pixelRatio);
          canvas.width = options.width * pixelRatio;
          canvas.height = options.height * pixelRatio;
          canvas.style.width = options.width + 'px';
          canvas.style.height = options.height + 'px';
          render.context.scale(pixelRatio, pixelRatio);
      };
  
      /**
       * Renders the given `engine`'s `Matter.World` object.
       * This is the entry point for all rendering and should be called every time the scene changes.
       * @method world
       * @param {engine} engine
       */
      Render.world = function(engine) {
          var render = engine.render,
              world = engine.world,
              canvas = render.canvas,
              context = render.context,
              options = render.options,
              allBodies = Composite.allBodies(world),
              allConstraints = Composite.allConstraints(world),
              background = options.wireframes ? options.wireframeBackground : options.background,
              bodies = [],
              constraints = [],
              i;
  
          var event = {
              timestamp: engine.timing.timestamp
          };
  
          Events.trigger(render, 'beforeRender', event);
  
          // apply background if it has changed
          if (render.currentBackground !== background)
              _applyBackground(render, background);
  
          // clear the canvas with a transparent fill, to allow the canvas background to show
          context.globalCompositeOperation = 'source-in';
          context.fillStyle = "transparent";
          context.fillRect(0, 0, canvas.width, canvas.height);
          context.globalCompositeOperation = 'source-over';
  
          // handle bounds
          if (options.hasBounds) {
              var boundsWidth = render.bounds.max.x - render.bounds.min.x,
                  boundsHeight = render.bounds.max.y - render.bounds.min.y,
                  boundsScaleX = boundsWidth / options.width,
                  boundsScaleY = boundsHeight / options.height;
  
              // filter out bodies that are not in view
              for (i = 0; i < allBodies.length; i++) {
                  var body = allBodies[i];
                  if (Bounds.overlaps(body.bounds, render.bounds))
                      bodies.push(body);
              }
  
              // filter out constraints that are not in view
              for (i = 0; i < allConstraints.length; i++) {
                  var constraint = allConstraints[i],
                      bodyA = constraint.bodyA,
                      bodyB = constraint.bodyB,
                      pointAWorld = constraint.pointA,
                      pointBWorld = constraint.pointB;
  
                  if (bodyA) pointAWorld = Vector.add(bodyA.position, constraint.pointA);
                  if (bodyB) pointBWorld = Vector.add(bodyB.position, constraint.pointB);
  
                  if (!pointAWorld || !pointBWorld)
                      continue;
  
                  if (Bounds.contains(render.bounds, pointAWorld) || Bounds.contains(render.bounds, pointBWorld))
                      constraints.push(constraint);
              }
  
              // transform the view
              context.scale(1 / boundsScaleX, 1 / boundsScaleY);
              context.translate(-render.bounds.min.x, -render.bounds.min.y);
          } else {
              constraints = allConstraints;
              bodies = allBodies;
          }
  
          if (!options.wireframes || (engine.enableSleeping && options.showSleeping)) {
              // fully featured rendering of bodies
              Render.bodies(engine, bodies, context);
          } else {
              if (options.showConvexHulls)
                  Render.bodyConvexHulls(engine, bodies, context);
  
              // optimised method for wireframes only
              Render.bodyWireframes(engine, bodies, context);
          }
  
          if (options.showBounds)
              Render.bodyBounds(engine, bodies, context);
  
          if (options.showAxes || options.showAngleIndicator)
              Render.bodyAxes(engine, bodies, context);
          
          if (options.showPositions)
              Render.bodyPositions(engine, bodies, context);
  
          if (options.showVelocity)
              Render.bodyVelocity(engine, bodies, context);
  
          if (options.showIds)
              Render.bodyIds(engine, bodies, context);
  
          if (options.showSeparations)
              Render.separations(engine, engine.pairs.list, context);
  
          if (options.showCollisions)
              Render.collisions(engine, engine.pairs.list, context);
  
          if (options.showVertexNumbers)
              Render.vertexNumbers(engine, bodies, context);
  
          if (options.showMousePosition)
              Render.mousePosition(engine, render.mouse, context);
  
          Render.constraints(constraints, context);
  
          if (options.showBroadphase && engine.broadphase.controller === Grid)
              Render.grid(engine, engine.broadphase, context);
  
          if (options.showDebug)
              Render.debug(engine, context);
  
          if (options.hasBounds) {
              // revert view transforms
              context.setTransform(options.pixelRatio, 0, 0, options.pixelRatio, 0, 0);
          }
  
          Events.trigger(render, 'afterRender', event);
      };
  
      /**
       * Description
       * @private
       * @method debug
       * @param {engine} engine
       * @param {RenderingContext} context
       */
      Render.debug = function(engine, context) {
          var c = context,
              world = engine.world,
              render = engine.render,
              metrics = engine.metrics,
              options = render.options,
              bodies = Composite.allBodies(world),
              space = "    ";
  
          if (engine.timing.timestamp - (render.debugTimestamp || 0) >= 500) {
              var text = "";
  
              if (metrics.timing) {
                  text += "fps: " + Math.round(metrics.timing.fps) + space;
              }
  
  
              render.debugString = text;
              render.debugTimestamp = engine.timing.timestamp;
          }
  
          if (render.debugString) {
              c.font = "12px Arial";
  
              if (options.wireframes) {
                  c.fillStyle = 'rgba(255,255,255,0.5)';
              } else {
                  c.fillStyle = 'rgba(0,0,0,0.5)';
              }
  
              var split = render.debugString.split('\n');
  
              for (var i = 0; i < split.length; i++) {
                  c.fillText(split[i], 50, 50 + i * 18);
              }
          }
      };
  
      /**
       * Description
       * @private
       * @method constraints
       * @param {constraint[]} constraints
       * @param {RenderingContext} context
       */
      Render.constraints = function(constraints, context) {
          var c = context;
  
          for (var i = 0; i < constraints.length; i++) {
              var constraint = constraints[i];
  
              if (!constraint.render.visible || !constraint.pointA || !constraint.pointB)
                  continue;
  
              var bodyA = constraint.bodyA,
                  bodyB = constraint.bodyB;
  
              if (bodyA) {
                  c.beginPath();
                  c.moveTo(bodyA.position.x + constraint.pointA.x, bodyA.position.y + constraint.pointA.y);
              } else {
                  c.beginPath();
                  c.moveTo(constraint.pointA.x, constraint.pointA.y);
              }
  
              if (bodyB) {
                  c.lineTo(bodyB.position.x + constraint.pointB.x, bodyB.position.y + constraint.pointB.y);
              } else {
                  c.lineTo(constraint.pointB.x, constraint.pointB.y);
              }
  
              c.lineWidth = constraint.render.lineWidth;
              c.strokeStyle = constraint.render.strokeStyle;
              c.stroke();
          }
      };
      
      /**
       * Description
       * @private
       * @method bodyShadows
       * @param {engine} engine
       * @param {body[]} bodies
       * @param {RenderingContext} context
       */
      Render.bodyShadows = function(engine, bodies, context) {
          var c = context,
              render = engine.render;
  
          for (var i = 0; i < bodies.length; i++) {
              var body = bodies[i];
  
              if (!body.render.visible)
                  continue;
  
              if (body.circleRadius) {
                  c.beginPath();
                  c.arc(body.position.x, body.position.y, body.circleRadius, 0, 2 * Math.PI);
                  c.closePath();
              } else {
                  c.beginPath();
                  c.moveTo(body.vertices[0].x, body.vertices[0].y);
                  for (var j = 1; j < body.vertices.length; j++) {
                      c.lineTo(body.vertices[j].x, body.vertices[j].y);
                  }
                  c.closePath();
              }
  
              var distanceX = body.position.x - render.options.width * 0.5,
                  distanceY = body.position.y - render.options.height * 0.2,
                  distance = Math.abs(distanceX) + Math.abs(distanceY);
  
              c.shadowColor = 'rgba(0,0,0,0.15)';
              c.shadowOffsetX = 0.05 * distanceX;
              c.shadowOffsetY = 0.05 * distanceY;
              c.shadowBlur = 1 + 12 * Math.min(1, distance / 1000);
  
              c.fill();
  
              c.shadowColor = null;
              c.shadowOffsetX = null;
              c.shadowOffsetY = null;
              c.shadowBlur = null;
          }
      };
  
      /**
       * Description
       * @private
       * @method bodies
       * @param {engine} engine
       * @param {body[]} bodies
       * @param {RenderingContext} context
       */
      Render.bodies = function(engine, bodies, context) {
          var c = context,
              render = engine.render,
              options = render.options,
              body,
              part,
              i,
              k;
  
          for (i = 0; i < bodies.length; i++) {
              body = bodies[i];
  
              if (!body.render.visible)
                  continue;
  
              // handle compound parts
              for (k = body.parts.length > 1 ? 1 : 0; k < body.parts.length; k++) {
                  part = body.parts[k];
  
                  if (!part.render.visible)
                      continue;
  
                  if (part.render.sprite && part.render.sprite.texture && !options.wireframes) {
                      // part sprite
                      var sprite = part.render.sprite,
                          texture = _getTexture(render, sprite.texture);
  
                      if (options.showSleeping && body.isSleeping) 
                          c.globalAlpha = 0.5;
  
                      c.translate(part.position.x, part.position.y); 
                      c.rotate(part.angle);
  
                      c.drawImage(
                          texture,
                          texture.width * -sprite.xOffset * sprite.xScale, 
                          texture.height * -sprite.yOffset * sprite.yScale, 
                          texture.width * sprite.xScale, 
                          texture.height * sprite.yScale
                      );
  
                      // revert translation, hopefully faster than save / restore
                      c.rotate(-part.angle);
                      c.translate(-part.position.x, -part.position.y); 
  
                      if (options.showSleeping && body.isSleeping) 
                          c.globalAlpha = 1;
                  } else {
                      // part polygon
                      if (part.circleRadius) {
                          c.beginPath();
                          c.arc(part.position.x, part.position.y, part.circleRadius, 0, 2 * Math.PI);
                      } else {
                          c.beginPath();
                          c.moveTo(part.vertices[0].x, part.vertices[0].y);
                          for (var j = 1; j < part.vertices.length; j++) {
                              c.lineTo(part.vertices[j].x, part.vertices[j].y);
                          }
                          c.closePath();
                      }
  
                      if (!options.wireframes) {
                          if (options.showSleeping && body.isSleeping) {
                              c.fillStyle = Common.shadeColor(part.render.fillStyle, 50);
                          } else {
                              c.fillStyle = part.render.fillStyle;
                          }
  
                          c.lineWidth = part.render.lineWidth;
                          c.strokeStyle = part.render.strokeStyle;
                          c.fill();
                          c.stroke();
                      } else {
                          c.lineWidth = 1;
                          c.strokeStyle = '#bbb';
                          if (options.showSleeping && body.isSleeping)
                              c.strokeStyle = 'rgba(255,255,255,0.2)';
                          c.stroke();
                      }
                  }
              }
          }
      };
  
      /**
       * Optimised method for drawing body wireframes in one pass
       * @private
       * @method bodyWireframes
       * @param {engine} engine
       * @param {body[]} bodies
       * @param {RenderingContext} context
       */
      Render.bodyWireframes = function(engine, bodies, context) {
          var c = context,
              showInternalEdges = engine.render.options.showInternalEdges,
              body,
              part,
              i,
              j,
              k;
  
          c.beginPath();
  
          // render all bodies
          for (i = 0; i < bodies.length; i++) {
              body = bodies[i];
  
              if (!body.render.visible)
                  continue;
  
              // handle compound parts
              for (k = body.parts.length > 1 ? 1 : 0; k < body.parts.length; k++) {
                  part = body.parts[k];
  
                  c.moveTo(part.vertices[0].x, part.vertices[0].y);
  
                  for (j = 1; j < part.vertices.length; j++) {
                      if (!part.vertices[j - 1].isInternal || showInternalEdges) {
                          c.lineTo(part.vertices[j].x, part.vertices[j].y);
                      } else {
                          c.moveTo(part.vertices[j].x, part.vertices[j].y);
                      }
  
                      if (part.vertices[j].isInternal && !showInternalEdges) {
                          c.moveTo(part.vertices[(j + 1) % part.vertices.length].x, part.vertices[(j + 1) % part.vertices.length].y);
                      }
                  }
                  
                  c.lineTo(part.vertices[0].x, part.vertices[0].y);
              }
          }
  
          c.lineWidth = 1;
          c.strokeStyle = '#bbb';
          c.stroke();
      };
  
      /**
       * Optimised method for drawing body convex hull wireframes in one pass
       * @private
       * @method bodyConvexHulls
       * @param {engine} engine
       * @param {body[]} bodies
       * @param {RenderingContext} context
       */
      Render.bodyConvexHulls = function(engine, bodies, context) {
          var c = context,
              body,
              part,
              i,
              j,
              k;
  
          c.beginPath();
  
          // render convex hulls
          for (i = 0; i < bodies.length; i++) {
              body = bodies[i];
  
              if (!body.render.visible || body.parts.length === 1)
                  continue;
  
              c.moveTo(body.vertices[0].x, body.vertices[0].y);
  
              for (j = 1; j < body.vertices.length; j++) {
                  c.lineTo(body.vertices[j].x, body.vertices[j].y);
              }
              
              c.lineTo(body.vertices[0].x, body.vertices[0].y);
          }
  
          c.lineWidth = 1;
          c.strokeStyle = 'rgba(255,255,255,0.2)';
          c.stroke();
      };
  
      /**
       * Renders body vertex numbers.
       * @private
       * @method vertexNumbers
       * @param {engine} engine
       * @param {body[]} bodies
       * @param {RenderingContext} context
       */
      Render.vertexNumbers = function(engine, bodies, context) {
          var c = context,
              i,
              j,
              k;
  
          for (i = 0; i < bodies.length; i++) {
              var parts = bodies[i].parts;
              for (k = parts.length > 1 ? 1 : 0; k < parts.length; k++) {
                  var part = parts[k];
                  for (j = 0; j < part.vertices.length; j++) {
                      c.fillStyle = 'rgba(255,255,255,0.2)';
                      c.fillText(i + '_' + j, part.position.x + (part.vertices[j].x - part.position.x) * 0.8, part.position.y + (part.vertices[j].y - part.position.y) * 0.8);
                  }
              }
          }
      };
  
      /**
       * Renders mouse position.
       * @private
       * @method mousePosition
       * @param {engine} engine
       * @param {mouse} mouse
       * @param {RenderingContext} context
       */
      Render.mousePosition = function(engine, mouse, context) {
          var c = context;
          c.fillStyle = 'rgba(255,255,255,0.8)';
          c.fillText(mouse.position.x + '  ' + mouse.position.y, mouse.position.x + 5, mouse.position.y - 5);
      };
  
      /**
       * Draws body bounds
       * @private
       * @method bodyBounds
       * @param {engine} engine
       * @param {body[]} bodies
       * @param {RenderingContext} context
       */
      Render.bodyBounds = function(engine, bodies, context) {
          var c = context,
              render = engine.render,
              options = render.options;
  
          c.beginPath();
  
          for (var i = 0; i < bodies.length; i++) {
              var body = bodies[i];
  
              if (body.render.visible) {
                  var parts = bodies[i].parts;
                  for (var j = parts.length > 1 ? 1 : 0; j < parts.length; j++) {
                      var part = parts[j];
                      c.rect(part.bounds.min.x, part.bounds.min.y, part.bounds.max.x - part.bounds.min.x, part.bounds.max.y - part.bounds.min.y);
                  }
              }
          }
  
          if (options.wireframes) {
              c.strokeStyle = 'rgba(255,255,255,0.08)';
          } else {
              c.strokeStyle = 'rgba(0,0,0,0.1)';
          }
  
          c.lineWidth = 1;
          c.stroke();
      };
  
      /**
       * Draws body angle indicators and axes
       * @private
       * @method bodyAxes
       * @param {engine} engine
       * @param {body[]} bodies
       * @param {RenderingContext} context
       */
      Render.bodyAxes = function(engine, bodies, context) {
          var c = context,
              render = engine.render,
              options = render.options,
              part,
              i,
              j,
              k;
  
          c.beginPath();
  
          for (i = 0; i < bodies.length; i++) {
              var body = bodies[i],
                  parts = body.parts;
  
              if (!body.render.visible)
                  continue;
  
              if (options.showAxes) {
                  // render all axes
                  for (j = parts.length > 1 ? 1 : 0; j < parts.length; j++) {
                      part = parts[j];
                      for (k = 0; k < part.axes.length; k++) {
                          var axis = part.axes[k];
                          c.moveTo(part.position.x, part.position.y);
                          c.lineTo(part.position.x + axis.x * 20, part.position.y + axis.y * 20);
                      }
                  }
              } else {
                  for (j = parts.length > 1 ? 1 : 0; j < parts.length; j++) {
                      part = parts[j];
                      for (k = 0; k < part.axes.length; k++) {
                          // render a single axis indicator
                          c.moveTo(part.position.x, part.position.y);
                          c.lineTo((part.vertices[0].x + part.vertices[part.vertices.length-1].x) / 2, 
                                   (part.vertices[0].y + part.vertices[part.vertices.length-1].y) / 2);
                      }
                  }
              }
          }
  
          if (options.wireframes) {
              c.strokeStyle = 'indianred';
          } else {
              c.strokeStyle = 'rgba(0,0,0,0.3)';
          }
  
          c.lineWidth = 1;
          c.stroke();
      };
  
      /**
       * Draws body positions
       * @private
       * @method bodyPositions
       * @param {engine} engine
       * @param {body[]} bodies
       * @param {RenderingContext} context
       */
      Render.bodyPositions = function(engine, bodies, context) {
          var c = context,
              render = engine.render,
              options = render.options,
              body,
              part,
              i,
              k;
  
          c.beginPath();
  
          // render current positions
          for (i = 0; i < bodies.length; i++) {
              body = bodies[i];
  
              if (!body.render.visible)
                  continue;
  
              // handle compound parts
              for (k = 0; k < body.parts.length; k++) {
                  part = body.parts[k];
                  c.arc(part.position.x, part.position.y, 3, 0, 2 * Math.PI, false);
                  c.closePath();
              }
          }
  
          if (options.wireframes) {
              c.fillStyle = 'indianred';
          } else {
              c.fillStyle = 'rgba(0,0,0,0.5)';
          }
          c.fill();
  
          c.beginPath();
  
          // render previous positions
          for (i = 0; i < bodies.length; i++) {
              body = bodies[i];
              if (body.render.visible) {
                  c.arc(body.positionPrev.x, body.positionPrev.y, 2, 0, 2 * Math.PI, false);
                  c.closePath();
              }
          }
  
          c.fillStyle = 'rgba(255,165,0,0.8)';
          c.fill();
      };
  
      /**
       * Draws body velocity
       * @private
       * @method bodyVelocity
       * @param {engine} engine
       * @param {body[]} bodies
       * @param {RenderingContext} context
       */
      Render.bodyVelocity = function(engine, bodies, context) {
          var c = context;
  
          c.beginPath();
  
          for (var i = 0; i < bodies.length; i++) {
              var body = bodies[i];
  
              if (!body.render.visible)
                  continue;
  
              c.moveTo(body.position.x, body.position.y);
              c.lineTo(body.position.x + (body.position.x - body.positionPrev.x) * 2, body.position.y + (body.position.y - body.positionPrev.y) * 2);
          }
  
          c.lineWidth = 3;
          c.strokeStyle = 'cornflowerblue';
          c.stroke();
      };
  
      /**
       * Draws body ids
       * @private
       * @method bodyIds
       * @param {engine} engine
       * @param {body[]} bodies
       * @param {RenderingContext} context
       */
      Render.bodyIds = function(engine, bodies, context) {
          var c = context,
              i,
              j;
  
          for (i = 0; i < bodies.length; i++) {
              if (!bodies[i].render.visible)
                  continue;
  
              var parts = bodies[i].parts;
              for (j = parts.length > 1 ? 1 : 0; j < parts.length; j++) {
                  var part = parts[j];
                  c.font = "12px Arial";
                  c.fillStyle = 'rgba(255,255,255,0.5)';
                  c.fillText(part.id, part.position.x + 10, part.position.y - 10);
              }
          }
      };
  
      /**
       * Description
       * @private
       * @method collisions
       * @param {engine} engine
       * @param {pair[]} pairs
       * @param {RenderingContext} context
       */
      Render.collisions = function(engine, pairs, context) {
          var c = context,
              options = engine.render.options,
              pair,
              collision,
              corrected,
              bodyA,
              bodyB,
              i,
              j;
  
          c.beginPath();
  
          // render collision positions
          for (i = 0; i < pairs.length; i++) {
              pair = pairs[i];
  
              if (!pair.isActive)
                  continue;
  
              collision = pair.collision;
              for (j = 0; j < pair.activeContacts.length; j++) {
                  var contact = pair.activeContacts[j],
                      vertex = contact.vertex;
                  c.rect(vertex.x - 1.5, vertex.y - 1.5, 3.5, 3.5);
              }
          }
  
          if (options.wireframes) {
              c.fillStyle = 'rgba(255,255,255,0.7)';
          } else {
              c.fillStyle = 'orange';
          }
          c.fill();
  
          c.beginPath();
              
          // render collision normals
          for (i = 0; i < pairs.length; i++) {
              pair = pairs[i];
  
              if (!pair.isActive)
                  continue;
  
              collision = pair.collision;
  
              if (pair.activeContacts.length > 0) {
                  var normalPosX = pair.activeContacts[0].vertex.x,
                      normalPosY = pair.activeContacts[0].vertex.y;
  
                  if (pair.activeContacts.length === 2) {
                      normalPosX = (pair.activeContacts[0].vertex.x + pair.activeContacts[1].vertex.x) / 2;
                      normalPosY = (pair.activeContacts[0].vertex.y + pair.activeContacts[1].vertex.y) / 2;
                  }
                  
                  if (collision.bodyB === collision.supports[0].body || collision.bodyA.isStatic === true) {
                      c.moveTo(normalPosX - collision.normal.x * 8, normalPosY - collision.normal.y * 8);
                  } else {
                      c.moveTo(normalPosX + collision.normal.x * 8, normalPosY + collision.normal.y * 8);
                  }
  
                  c.lineTo(normalPosX, normalPosY);
              }
          }
  
          if (options.wireframes) {
              c.strokeStyle = 'rgba(255,165,0,0.7)';
          } else {
              c.strokeStyle = 'orange';
          }
  
          c.lineWidth = 1;
          c.stroke();
      };
  
      /**
       * Description
       * @private
       * @method separations
       * @param {engine} engine
       * @param {pair[]} pairs
       * @param {RenderingContext} context
       */
      Render.separations = function(engine, pairs, context) {
          var c = context,
              options = engine.render.options,
              pair,
              collision,
              corrected,
              bodyA,
              bodyB,
              i,
              j;
  
          c.beginPath();
  
          // render separations
          for (i = 0; i < pairs.length; i++) {
              pair = pairs[i];
  
              if (!pair.isActive)
                  continue;
  
              collision = pair.collision;
              bodyA = collision.bodyA;
              bodyB = collision.bodyB;
  
              var k = 1;
  
              if (!bodyB.isStatic && !bodyA.isStatic) k = 0.5;
              if (bodyB.isStatic) k = 0;
  
              c.moveTo(bodyB.position.x, bodyB.position.y);
              c.lineTo(bodyB.position.x - collision.penetration.x * k, bodyB.position.y - collision.penetration.y * k);
  
              k = 1;
  
              if (!bodyB.isStatic && !bodyA.isStatic) k = 0.5;
              if (bodyA.isStatic) k = 0;
  
              c.moveTo(bodyA.position.x, bodyA.position.y);
              c.lineTo(bodyA.position.x + collision.penetration.x * k, bodyA.position.y + collision.penetration.y * k);
          }
  
          if (options.wireframes) {
              c.strokeStyle = 'rgba(255,165,0,0.5)';
          } else {
              c.strokeStyle = 'orange';
          }
          c.stroke();
      };
  
      /**
       * Description
       * @private
       * @method grid
       * @param {engine} engine
       * @param {grid} grid
       * @param {RenderingContext} context
       */
      Render.grid = function(engine, grid, context) {
          var c = context,
              options = engine.render.options;
  
          if (options.wireframes) {
              c.strokeStyle = 'rgba(255,180,0,0.1)';
          } else {
              c.strokeStyle = 'rgba(255,180,0,0.5)';
          }
  
          c.beginPath();
  
          var bucketKeys = Common.keys(grid.buckets);
  
          for (var i = 0; i < bucketKeys.length; i++) {
              var bucketId = bucketKeys[i];
  
              if (grid.buckets[bucketId].length < 2)
                  continue;
  
              var region = bucketId.split(',');
              c.rect(0.5 + parseInt(region[0], 10) * grid.bucketWidth, 
                      0.5 + parseInt(region[1], 10) * grid.bucketHeight, 
                      grid.bucketWidth, 
                      grid.bucketHeight);
          }
  
          c.lineWidth = 1;
          c.stroke();
      };
  
      /**
       * Description
       * @private
       * @method inspector
       * @param {inspector} inspector
       * @param {RenderingContext} context
       */
      Render.inspector = function(inspector, context) {
          var engine = inspector.engine,
              selected = inspector.selected,
              render = engine.render,
              options = render.options,
              bounds;
  
          if (options.hasBounds) {
              var boundsWidth = render.bounds.max.x - render.bounds.min.x,
                  boundsHeight = render.bounds.max.y - render.bounds.min.y,
                  boundsScaleX = boundsWidth / render.options.width,
                  boundsScaleY = boundsHeight / render.options.height;
              
              context.scale(1 / boundsScaleX, 1 / boundsScaleY);
              context.translate(-render.bounds.min.x, -render.bounds.min.y);
          }
  
          for (var i = 0; i < selected.length; i++) {
              var item = selected[i].data;
  
              context.translate(0.5, 0.5);
              context.lineWidth = 1;
              context.strokeStyle = 'rgba(255,165,0,0.9)';
              context.setLineDash([1,2]);
  
              switch (item.type) {
  
              case 'body':
  
                  // render body selections
                  bounds = item.bounds;
                  context.beginPath();
                  context.rect(Math.floor(bounds.min.x - 3), Math.floor(bounds.min.y - 3), 
                               Math.floor(bounds.max.x - bounds.min.x + 6), Math.floor(bounds.max.y - bounds.min.y + 6));
                  context.closePath();
                  context.stroke();
  
                  break;
  
              case 'constraint':
  
                  // render constraint selections
                  var point = item.pointA;
                  if (item.bodyA)
                      point = item.pointB;
                  context.beginPath();
                  context.arc(point.x, point.y, 10, 0, 2 * Math.PI);
                  context.closePath();
                  context.stroke();
  
                  break;
  
              }
  
              context.setLineDash([]);
              context.translate(-0.5, -0.5);
          }
  
          // render selection region
          if (inspector.selectStart !== null) {
              context.translate(0.5, 0.5);
              context.lineWidth = 1;
              context.strokeStyle = 'rgba(255,165,0,0.6)';
              context.fillStyle = 'rgba(255,165,0,0.1)';
              bounds = inspector.selectBounds;
              context.beginPath();
              context.rect(Math.floor(bounds.min.x), Math.floor(bounds.min.y), 
                           Math.floor(bounds.max.x - bounds.min.x), Math.floor(bounds.max.y - bounds.min.y));
              context.closePath();
              context.stroke();
              context.fill();
              context.translate(-0.5, -0.5);
          }
  
          if (options.hasBounds)
              context.setTransform(1, 0, 0, 1, 0, 0);
      };
  
      /**
       * Description
       * @method _createCanvas
       * @private
       * @param {} width
       * @param {} height
       * @return canvas
       */
      var _createCanvas = function(width, height) {
          var canvas = document.createElement('canvas');
          canvas.width = width;
          canvas.height = height;
          canvas.oncontextmenu = function() { return false; };
          canvas.onselectstart = function() { return false; };
          return canvas;
      };
  
      /**
       * Gets the pixel ratio of the canvas.
       * @method _getPixelRatio
       * @private
       * @param {HTMLElement} canvas
       * @return {Number} pixel ratio
       */
      var _getPixelRatio = function(canvas) {
          var context = canvas.getContext('2d'),
              devicePixelRatio = window.devicePixelRatio || 1,
              backingStorePixelRatio = context.webkitBackingStorePixelRatio || context.mozBackingStorePixelRatio
                                        || context.msBackingStorePixelRatio || context.oBackingStorePixelRatio
                                        || context.backingStorePixelRatio || 1;
  
          return devicePixelRatio / backingStorePixelRatio;
      };
  
      /**
       * Gets the requested texture (an Image) via its path
       * @method _getTexture
       * @private
       * @param {render} render
       * @param {string} imagePath
       * @return {Image} texture
       */
      var _getTexture = function(render, imagePath) {
          var image = render.textures[imagePath];
  
          if (image)
              return image;
  
          image = render.textures[imagePath] = new Image();
          image.src = imagePath;
  
          return image;
      };
  
      /**
       * Applies the background to the canvas using CSS.
       * @method applyBackground
       * @private
       * @param {render} render
       * @param {string} background
       */
      var _applyBackground = function(render, background) {
          var cssBackground = background;
  
          if (/(jpg|gif|png)$/.test(background))
              cssBackground = 'url(' + background + ')';
  
          render.canvas.style.background = cssBackground;
          render.canvas.style.backgroundSize = "contain";
          render.currentBackground = background;
      };
  
      /*
      *
      *  Events Documentation
      *
      */
  
      /**
      * Fired before rendering
      *
      * @event beforeRender
      * @param {} event An event object
      * @param {number} event.timestamp The engine.timing.timestamp of the event
      * @param {} event.source The source object of the event
      * @param {} event.name The name of the event
      */
  
      /**
      * Fired after rendering
      *
      * @event afterRender
      * @param {} event An event object
      * @param {number} event.timestamp The engine.timing.timestamp of the event
      * @param {} event.source The source object of the event
      * @param {} event.name The name of the event
      */
  
      /*
      *
      *  Properties Documentation
      *
      */
  
      /**
       * A back-reference to the `Matter.Render` module.
       *
       * @property controller
       * @type render
       */
  
      /**
       * A reference to the element where the canvas is to be inserted (if `render.canvas` has not been specified)
       *
       * @property element
       * @type HTMLElement
       * @default null
       */
  
      /**
       * The canvas element to render to. If not specified, one will be created if `render.element` has been specified.
       *
       * @property canvas
       * @type HTMLCanvasElement
       * @default null
       */
  
      /**
       * The configuration options of the renderer.
       *
       * @property options
       * @type {}
       */
  
      /**
       * The target width in pixels of the `render.canvas` to be created.
       *
       * @property options.width
       * @type number
       * @default 800
       */
  
      /**
       * The target height in pixels of the `render.canvas` to be created.
       *
       * @property options.height
       * @type number
       * @default 600
       */
  
      /**
       * A flag that specifies if `render.bounds` should be used when rendering.
       *
       * @property options.hasBounds
       * @type boolean
       * @default false
       */
  
      /**
       * A `Bounds` object that specifies the drawing view region. 
       * Rendering will be automatically transformed and scaled to fit within the canvas size (`render.options.width` and `render.options.height`).
       * This allows for creating views that can pan or zoom around the scene.
       * You must also set `render.options.hasBounds` to `true` to enable bounded rendering.
       *
       * @property bounds
       * @type bounds
       */
  
      /**
       * The 2d rendering context from the `render.canvas` element.
       *
       * @property context
       * @type CanvasRenderingContext2D
       */
  
      /**
       * The sprite texture cache.
       *
       * @property textures
       * @type {}
       */
  
  })();
  
  },{"../body/Composite":2,"../collision/Grid":6,"../core/Common":14,"../core/Events":16,"../geometry/Bounds":24,"../geometry/Vector":26}],30:[function(require,module,exports){
  /**
  * See the included usage [examples](https://github.com/liabru/matter-js/tree/master/examples).
  *
  * @class RenderPixi
  */
  
  var RenderPixi = {};
  
  module.exports = RenderPixi;
  
  var Composite = require('../body/Composite');
  var Common = require('../core/Common');
  
  (function() {
      
      /**
       * Creates a new Pixi.js WebGL renderer
       * @method create
       * @param {object} options
       * @return {RenderPixi} A new renderer
       */
      RenderPixi.create = function(options) {
          var defaults = {
              controller: RenderPixi,
              element: null,
              canvas: null,
              options: {
                  width: 800,
                  height: 600,
                  background: '#fafafa',
                  wireframeBackground: '#222',
                  hasBounds: false,
                  enabled: true,
                  wireframes: true,
                  showSleeping: true,
                  showDebug: false,
                  showBroadphase: false,
                  showBounds: false,
                  showVelocity: false,
                  showCollisions: false,
                  showAxes: false,
                  showPositions: false,
                  showAngleIndicator: false,
                  showIds: false,
                  showShadows: false
              }
          };
  
          var render = Common.extend(defaults, options),
              transparent = !render.options.wireframes && render.options.background === 'transparent';
  
          // init pixi
          render.context = new PIXI.WebGLRenderer(render.options.width, render.options.height, {
              view: render.canvas,
              transparent: transparent,
              antialias: true,
              backgroundColor: options.background
          });
          
          render.canvas = render.context.view;
          render.container = new PIXI.Container();
          render.bounds = render.bounds || { 
              min: { 
                  x: 0,
                  y: 0
              }, 
              max: { 
                  x: render.options.width,
                  y: render.options.height
              }
          };
  
          // caches
          render.textures = {};
          render.sprites = {};
          render.primitives = {};
  
          // use a sprite batch for performance
          render.spriteContainer = new PIXI.Container();
          render.container.addChild(render.spriteContainer);
  
          // insert canvas
          if (Common.isElement(render.element)) {
              render.element.appendChild(render.canvas);
          } else {
              Common.log('No "render.element" passed, "render.canvas" was not inserted into document.', 'warn');
          }
  
          // prevent menus on canvas
          render.canvas.oncontextmenu = function() { return false; };
          render.canvas.onselectstart = function() { return false; };
  
          return render;
      };
  
      /**
       * Clears the scene graph
       * @method clear
       * @param {RenderPixi} render
       */
      RenderPixi.clear = function(render) {
          var container = render.container,
              spriteContainer = render.spriteContainer;
  
          // clear stage container
          while (container.children[0]) { 
              container.removeChild(container.children[0]); 
          }
  
          // clear sprite batch
          while (spriteContainer.children[0]) { 
              spriteContainer.removeChild(spriteContainer.children[0]); 
          }
  
          var bgSprite = render.sprites['bg-0'];
  
          // clear caches
          render.textures = {};
          render.sprites = {};
          render.primitives = {};
  
          // set background sprite
          render.sprites['bg-0'] = bgSprite;
          if (bgSprite)
              container.addChildAt(bgSprite, 0);
  
          // add sprite batch back into container
          render.container.addChild(render.spriteContainer);
  
          // reset background state
          render.currentBackground = null;
  
          // reset bounds transforms
          container.scale.set(1, 1);
          container.position.set(0, 0);
      };
  
      /**
       * Sets the background of the canvas 
       * @method setBackground
       * @param {RenderPixi} render
       * @param {string} background
       */
      RenderPixi.setBackground = function(render, background) {
          if (render.currentBackground !== background) {
              var isColor = background.indexOf && background.indexOf('#') !== -1,
                  bgSprite = render.sprites['bg-0'];
  
              if (isColor) {
                  // if solid background color
                  var color = Common.colorToNumber(background);
                  render.context.backgroundColor = color;
  
                  // remove background sprite if existing
                  if (bgSprite)
                      render.container.removeChild(bgSprite); 
              } else {
                  // initialise background sprite if needed
                  if (!bgSprite) {
                      var texture = _getTexture(render, background);
  
                      bgSprite = render.sprites['bg-0'] = new PIXI.Sprite(texture);
                      bgSprite.position.x = 0;
                      bgSprite.position.y = 0;
                      render.container.addChildAt(bgSprite, 0);
                  }
              }
  
              render.currentBackground = background;
          }
      };
  
      /**
       * Description
       * @method world
       * @param {engine} engine
       */
      RenderPixi.world = function(engine) {
          var render = engine.render,
              world = engine.world,
              context = render.context,
              container = render.container,
              options = render.options,
              bodies = Composite.allBodies(world),
              allConstraints = Composite.allConstraints(world),
              constraints = [],
              i;
  
          if (options.wireframes) {
              RenderPixi.setBackground(render, options.wireframeBackground);
          } else {
              RenderPixi.setBackground(render, options.background);
          }
  
          // handle bounds
          var boundsWidth = render.bounds.max.x - render.bounds.min.x,
              boundsHeight = render.bounds.max.y - render.bounds.min.y,
              boundsScaleX = boundsWidth / render.options.width,
              boundsScaleY = boundsHeight / render.options.height;
  
          if (options.hasBounds) {
              // Hide bodies that are not in view
              for (i = 0; i < bodies.length; i++) {
                  var body = bodies[i];
                  body.render.sprite.visible = Bounds.overlaps(body.bounds, render.bounds);
              }
  
              // filter out constraints that are not in view
              for (i = 0; i < allConstraints.length; i++) {
                  var constraint = allConstraints[i],
                      bodyA = constraint.bodyA,
                      bodyB = constraint.bodyB,
                      pointAWorld = constraint.pointA,
                      pointBWorld = constraint.pointB;
  
                  if (bodyA) pointAWorld = Vector.add(bodyA.position, constraint.pointA);
                  if (bodyB) pointBWorld = Vector.add(bodyB.position, constraint.pointB);
  
                  if (!pointAWorld || !pointBWorld)
                      continue;
  
                  if (Bounds.contains(render.bounds, pointAWorld) || Bounds.contains(render.bounds, pointBWorld))
                      constraints.push(constraint);
              }
  
              // transform the view
              container.scale.set(1 / boundsScaleX, 1 / boundsScaleY);
              container.position.set(-render.bounds.min.x * (1 / boundsScaleX), -render.bounds.min.y * (1 / boundsScaleY));
          } else {
              constraints = allConstraints;
          }
  
          for (i = 0; i < bodies.length; i++)
              RenderPixi.body(engine, bodies[i]);
  
          for (i = 0; i < constraints.length; i++)
              RenderPixi.constraint(engine, constraints[i]);
  
          context.render(container);
      };
  
  
      /**
       * Description
       * @method constraint
       * @param {engine} engine
       * @param {constraint} constraint
       */
      RenderPixi.constraint = function(engine, constraint) {
          var render = engine.render,
              bodyA = constraint.bodyA,
              bodyB = constraint.bodyB,
              pointA = constraint.pointA,
              pointB = constraint.pointB,
              container = render.container,
              constraintRender = constraint.render,
              primitiveId = 'c-' + constraint.id,
              primitive = render.primitives[primitiveId];
  
          // initialise constraint primitive if not existing
          if (!primitive)
              primitive = render.primitives[primitiveId] = new PIXI.Graphics();
  
          // don't render if constraint does not have two end points
          if (!constraintRender.visible || !constraint.pointA || !constraint.pointB) {
              primitive.clear();
              return;
          }
  
          // add to scene graph if not already there
          if (Common.indexOf(container.children, primitive) === -1)
              container.addChild(primitive);
  
          // render the constraint on every update, since they can change dynamically
          primitive.clear();
          primitive.beginFill(0, 0);
          primitive.lineStyle(constraintRender.lineWidth, Common.colorToNumber(constraintRender.strokeStyle), 1);
          
          if (bodyA) {
              primitive.moveTo(bodyA.position.x + pointA.x, bodyA.position.y + pointA.y);
          } else {
              primitive.moveTo(pointA.x, pointA.y);
          }
  
          if (bodyB) {
              primitive.lineTo(bodyB.position.x + pointB.x, bodyB.position.y + pointB.y);
          } else {
              primitive.lineTo(pointB.x, pointB.y);
          }
  
          primitive.endFill();
      };
      
      /**
       * Description
       * @method body
       * @param {engine} engine
       * @param {body} body
       */
      RenderPixi.body = function(engine, body) {
          var render = engine.render,
              bodyRender = body.render;
  
          if (!bodyRender.visible)
              return;
  
          if (bodyRender.sprite && bodyRender.sprite.texture) {
              var spriteId = 'b-' + body.id,
                  sprite = render.sprites[spriteId],
                  spriteContainer = render.spriteContainer;
  
              // initialise body sprite if not existing
              if (!sprite)
                  sprite = render.sprites[spriteId] = _createBodySprite(render, body);
  
              // add to scene graph if not already there
              if (Common.indexOf(spriteContainer.children, sprite) === -1)
                  spriteContainer.addChild(sprite);
  
              // update body sprite
              sprite.position.x = body.position.x;
              sprite.position.y = body.position.y;
              sprite.rotation = body.angle;
              sprite.scale.x = bodyRender.sprite.xScale || 1;
              sprite.scale.y = bodyRender.sprite.yScale || 1;
          } else {
              var primitiveId = 'b-' + body.id,
                  primitive = render.primitives[primitiveId],
                  container = render.container;
  
              // initialise body primitive if not existing
              if (!primitive) {
                  primitive = render.primitives[primitiveId] = _createBodyPrimitive(render, body);
                  primitive.initialAngle = body.angle;
              }
  
              // add to scene graph if not already there
              if (Common.indexOf(container.children, primitive) === -1)
                  container.addChild(primitive);
  
              // update body primitive
              primitive.position.x = body.position.x;
              primitive.position.y = body.position.y;
              primitive.rotation = body.angle - primitive.initialAngle;
          }
      };
  
      /**
       * Creates a body sprite
       * @method _createBodySprite
       * @private
       * @param {RenderPixi} render
       * @param {body} body
       * @return {PIXI.Sprite} sprite
       */
      var _createBodySprite = function(render, body) {
          var bodyRender = body.render,
              texturePath = bodyRender.sprite.texture,
              texture = _getTexture(render, texturePath),
              sprite = new PIXI.Sprite(texture);
  
          sprite.anchor.x = body.render.sprite.xOffset;
          sprite.anchor.y = body.render.sprite.yOffset;
  
          return sprite;
      };
  
      /**
       * Creates a body primitive
       * @method _createBodyPrimitive
       * @private
       * @param {RenderPixi} render
       * @param {body} body
       * @return {PIXI.Graphics} graphics
       */
      var _createBodyPrimitive = function(render, body) {
          var bodyRender = body.render,
              options = render.options,
              primitive = new PIXI.Graphics(),
              fillStyle = Common.colorToNumber(bodyRender.fillStyle),
              strokeStyle = Common.colorToNumber(bodyRender.strokeStyle),
              strokeStyleIndicator = Common.colorToNumber(bodyRender.strokeStyle),
              strokeStyleWireframe = Common.colorToNumber('#bbb'),
              strokeStyleWireframeIndicator = Common.colorToNumber('#CD5C5C'),
              part;
  
          primitive.clear();
  
          // handle compound parts
          for (var k = body.parts.length > 1 ? 1 : 0; k < body.parts.length; k++) {
              part = body.parts[k];
  
              if (!options.wireframes) {
                  primitive.beginFill(fillStyle, 1);
                  primitive.lineStyle(bodyRender.lineWidth, strokeStyle, 1);
              } else {
                  primitive.beginFill(0, 0);
                  primitive.lineStyle(1, strokeStyleWireframe, 1);
              }
  
              primitive.moveTo(part.vertices[0].x - body.position.x, part.vertices[0].y - body.position.y);
  
              for (var j = 1; j < part.vertices.length; j++) {
                  primitive.lineTo(part.vertices[j].x - body.position.x, part.vertices[j].y - body.position.y);
              }
  
              primitive.lineTo(part.vertices[0].x - body.position.x, part.vertices[0].y - body.position.y);
  
              primitive.endFill();
  
              // angle indicator
              if (options.showAngleIndicator || options.showAxes) {
                  primitive.beginFill(0, 0);
  
                  if (options.wireframes) {
                      primitive.lineStyle(1, strokeStyleWireframeIndicator, 1);
                  } else {
                      primitive.lineStyle(1, strokeStyleIndicator);
                  }
  
                  primitive.moveTo(part.position.x - body.position.x, part.position.y - body.position.y);
                  primitive.lineTo(((part.vertices[0].x + part.vertices[part.vertices.length-1].x) / 2 - body.position.x), 
                                   ((part.vertices[0].y + part.vertices[part.vertices.length-1].y) / 2 - body.position.y));
  
                  primitive.endFill();
              }
          }
  
          return primitive;
      };
  
      /**
       * Gets the requested texture (a PIXI.Texture) via its path
       * @method _getTexture
       * @private
       * @param {RenderPixi} render
       * @param {string} imagePath
       * @return {PIXI.Texture} texture
       */
      var _getTexture = function(render, imagePath) {
          var texture = render.textures[imagePath];
  
          if (!texture)
              texture = render.textures[imagePath] = PIXI.Texture.fromImage(imagePath);
  
          return texture;
      };
  
  })();
  
  },{"../body/Composite":2,"../core/Common":14}]},{},[28])(28)
  });