text: /**
   * @author       Richard Davey <rich@photonstorm.com>
   * @copyright    2020 Photon Storm Ltd.
   * @license      {@link https://opensource.org/licenses/MIT|MIT License}
   */
  
  /**
   * This module implements a modified ear slicing algorithm, optimized by z-order curve hashing and extended to
   * handle holes, twisted polygons, degeneracies and self-intersections in a way that doesn't guarantee correctness
   * of triangulation, but attempts to always produce acceptable results for practical data.
   *
   * Example:
   *
   * ```javascript
   * const triangles = Phaser.Geom.Polygon.Earcut([10,0, 0,50, 60,60, 70,10]); // returns [1,0,3, 3,2,1]
   * ```
   *
   * Each group of three vertex indices in the resulting array forms a triangle.
   *
   * ```javascript
   * // triangulating a polygon with a hole
   * earcut([0,0, 100,0, 100,100, 0,100,  20,20, 80,20, 80,80, 20,80], [4]);
   * // [3,0,4, 5,4,0, 3,4,7, 5,0,1, 2,3,7, 6,5,1, 2,7,6, 6,1,2]
   *
   * // triangulating a polygon with 3d coords
   * earcut([10,0,1, 0,50,2, 60,60,3, 70,10,4], null, 3);
   * // [1,0,3, 3,2,1]
   * ```
   *
   * If you pass a single vertex as a hole, Earcut treats it as a Steiner point.
   *
   * If your input is a multi-dimensional array (e.g. GeoJSON Polygon), you can convert it to the format
   * expected by Earcut with `Phaser.Geom.Polygon.Earcut.flatten`:
   *
   * ```javascript
   * var data = earcut.flatten(geojson.geometry.coordinates);
   * var triangles = earcut(data.vertices, data.holes, data.dimensions);
   * ```
   *
   * After getting a triangulation, you can verify its correctness with `Phaser.Geom.Polygon.Earcut.deviation`:
   *
   * ```javascript
   * var deviation = earcut.deviation(vertices, holes, dimensions, triangles);
   * ```
   * Returns the relative difference between the total area of triangles and the area of the input polygon.
   * 0 means the triangulation is fully correct.
   *
   * For more information see https://github.com/mapbox/earcut
   *
   * @function Phaser.Geom.Polygon.Earcut
   * @since 3.50.0
   *
   * @param {number[]} data - A flat array of vertex coordinate, like [x0,y0, x1,y1, x2,y2, ...]
   * @param {number[]} [holeIndices] - An array of hole indices if any (e.g. [5, 8] for a 12-vertex input would mean one hole with vertices 5–7 and another with 8–11).
   * @param {number} [dimensions=2] - The number of coordinates per vertex in the input array (2 by default).
   *
   * @return {number[]} An array of triangulated data.
   */
  
   //  Earcut 2.2.2 (January 21st 2020)
  
  /*
   * ISC License
   *
   * Copyright (c) 2016, Mapbox
   *
   * Permission to use, copy, modify, and/or distribute this software for any purpose
   * with or without fee is hereby granted, provided that the above copyright notice
   * and this permission notice appear in all copies.
   *
   * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
   * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
   * FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
   * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
   * OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
   * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
   * THIS SOFTWARE.
   */
  
  'use strict';
  
  function earcut(data, holeIndices, dim) {
  
      dim = dim || 2;
  
      var hasHoles = holeIndices && holeIndices.length,
          outerLen = hasHoles ? holeIndices[0] * dim : data.length,
          outerNode = linkedList(data, 0, outerLen, dim, true),
          triangles = [];
  
      if (!outerNode || outerNode.next === outerNode.prev) return triangles;
  
      var minX, minY, maxX, maxY, x, y, invSize;
  
      if (hasHoles) outerNode = eliminateHoles(data, holeIndices, outerNode, dim);
  
      // if the shape is not too simple, we'll use z-order curve hash later; calculate polygon bbox
      if (data.length > 80 * dim) {
          minX = maxX = data[0];
          minY = maxY = data[1];
  
          for (var i = dim; i < outerLen; i += dim) {
              x = data[i];
              y = data[i + 1];
              if (x < minX) minX = x;
              if (y < minY) minY = y;
              if (x > maxX) maxX = x;
              if (y > maxY) maxY = y;
          }
  
          // minX, minY and invSize are later used to transform coords into integers for z-order calculation
          invSize = Math.max(maxX - minX, maxY - minY);
          invSize = invSize !== 0 ? 1 / invSize : 0;
      }
  
      earcutLinked(outerNode, triangles, dim, minX, minY, invSize);
  
      return triangles;
  }
  
  // create a circular doubly linked list from polygon points in the specified winding order
  function linkedList(data, start, end, dim, clockwise) {
      var i, last;
  
      if (clockwise === (signedArea(data, start, end, dim) > 0)) {
          for (i = start; i < end; i += dim) last = insertNode(i, data[i], data[i + 1], last);
      } else {
          for (i = end - dim; i >= start; i -= dim) last = insertNode(i, data[i], data[i + 1], last);
      }
  
      if (last && equals(last, last.next)) {
          removeNode(last);
          last = last.next;
      }
  
      return last;
  }
  
  // eliminate colinear or duplicate points
  function filterPoints(start, end) {
      if (!start) return start;
      if (!end) end = start;
  
      var p = start,
          again;
      do {
          again = false;
  
          if (!p.steiner && (equals(p, p.next) || area(p.prev, p, p.next) === 0)) {
              removeNode(p);
              p = end = p.prev;
              if (p === p.next) break;
              again = true;
  
          } else {
              p = p.next;
          }
      } while (again || p !== end);
  
      return end;
  }
  
  // main ear slicing loop which triangulates a polygon (given as a linked list)
  function earcutLinked(ear, triangles, dim, minX, minY, invSize, pass) {
      if (!ear) return;
  
      // interlink polygon nodes in z-order
      if (!pass && invSize) indexCurve(ear, minX, minY, invSize);
  
      var stop = ear,
          prev, next;
  
      // iterate through ears, slicing them one by one
      while (ear.prev !== ear.next) {
          prev = ear.prev;
          next = ear.next;
  
          if (invSize ? isEarHashed(ear, minX, minY, invSize) : isEar(ear)) {
              // cut off the triangle
              triangles.push(prev.i / dim);
              triangles.push(ear.i / dim);
              triangles.push(next.i / dim);
  
              removeNode(ear);
  
              // skipping the next vertex leads to less sliver triangles
              ear = next.next;
              stop = next.next;
  
              continue;
          }
  
          ear = next;
  
          // if we looped through the whole remaining polygon and can't find any more ears
          if (ear === stop) {
              // try filtering points and slicing again
              if (!pass) {
                  earcutLinked(filterPoints(ear), triangles, dim, minX, minY, invSize, 1);
  
              // if this didn't work, try curing all small self-intersections locally
              } else if (pass === 1) {
                  ear = cureLocalIntersections(filterPoints(ear), triangles, dim);
                  earcutLinked(ear, triangles, dim, minX, minY, invSize, 2);
  
              // as a last resort, try splitting the remaining polygon into two
              } else if (pass === 2) {
                  splitEarcut(ear, triangles, dim, minX, minY, invSize);
              }
  
              break;
          }
      }
  }
  
  // check whether a polygon node forms a valid ear with adjacent nodes
  function isEar(ear) {
      var a = ear.prev,
          b = ear,
          c = ear.next;
  
      if (area(a, b, c) >= 0) return false; // reflex, can't be an ear
  
      // now make sure we don't have other points inside the potential ear
      var p = ear.next.next;
  
      while (p !== ear.prev) {
          if (pointInTriangle(a.x, a.y, b.x, b.y, c.x, c.y, p.x, p.y) &&
              area(p.prev, p, p.next) >= 0) return false;
          p = p.next;
      }
  
      return true;
  }
  
  function isEarHashed(ear, minX, minY, invSize) {
      var a = ear.prev,
          b = ear,
          c = ear.next;
  
      if (area(a, b, c) >= 0) return false; // reflex, can't be an ear
  
      // triangle bbox; min & max are calculated like this for speed
      var minTX = a.x < b.x ? (a.x < c.x ? a.x : c.x) : (b.x < c.x ? b.x : c.x),
          minTY = a.y < b.y ? (a.y < c.y ? a.y : c.y) : (b.y < c.y ? b.y : c.y),
          maxTX = a.x > b.x ? (a.x > c.x ? a.x : c.x) : (b.x > c.x ? b.x : c.x),
          maxTY = a.y > b.y ? (a.y > c.y ? a.y : c.y) : (b.y > c.y ? b.y : c.y);
  
      // z-order range for the current triangle bbox;
      var minZ = zOrder(minTX, minTY, minX, minY, invSize),
          maxZ = zOrder(maxTX, maxTY, minX, minY, invSize);
  
      var p = ear.prevZ,
          n = ear.nextZ;
  
      // look for points inside the triangle in both directions
      while (p && p.z >= minZ && n && n.z <= maxZ) {
          if (p !== ear.prev && p !== ear.next &&
              pointInTriangle(a.x, a.y, b.x, b.y, c.x, c.y, p.x, p.y) &&
              area(p.prev, p, p.next) >= 0) return false;
          p = p.prevZ;
  
          if (n !== ear.prev && n !== ear.next &&
              pointInTriangle(a.x, a.y, b.x, b.y, c.x, c.y, n.x, n.y) &&
              area(n.prev, n, n.next) >= 0) return false;
          n = n.nextZ;
      }
  
      // look for remaining points in decreasing z-order
      while (p && p.z >= minZ) {
          if (p !== ear.prev && p !== ear.next &&
              pointInTriangle(a.x, a.y, b.x, b.y, c.x, c.y, p.x, p.y) &&
              area(p.prev, p, p.next) >= 0) return false;
          p = p.prevZ;
      }
  
      // look for remaining points in increasing z-order
      while (n && n.z <= maxZ) {
          if (n !== ear.prev && n !== ear.next &&
              pointInTriangle(a.x, a.y, b.x, b.y, c.x, c.y, n.x, n.y) &&
              area(n.prev, n, n.next) >= 0) return false;
          n = n.nextZ;
      }
  
      return true;
  }
  
  // go through all polygon nodes and cure small local self-intersections
  function cureLocalIntersections(start, triangles, dim) {
      var p = start;
      do {
          var a = p.prev,
              b = p.next.next;
  
          if (!equals(a, b) && intersects(a, p, p.next, b) && locallyInside(a, b) && locallyInside(b, a)) {
  
              triangles.push(a.i / dim);
              triangles.push(p.i / dim);
              triangles.push(b.i / dim);
  
              // remove two nodes involved
              removeNode(p);
              removeNode(p.next);
  
              p = start = b;
          }
          p = p.next;
      } while (p !== start);
  
      return filterPoints(p);
  }
  
  // try splitting polygon into two and triangulate them independently
  function splitEarcut(start, triangles, dim, minX, minY, invSize) {
      // look for a valid diagonal that divides the polygon into two
      var a = start;
      do {
          var b = a.next.next;
          while (b !== a.prev) {
              if (a.i !== b.i && isValidDiagonal(a, b)) {
                  // split the polygon in two by the diagonal
                  var c = splitPolygon(a, b);
  
                  // filter colinear points around the cuts
                  a = filterPoints(a, a.next);
                  c = filterPoints(c, c.next);
  
                  // run earcut on each half
                  earcutLinked(a, triangles, dim, minX, minY, invSize);
                  earcutLinked(c, triangles, dim, minX, minY, invSize);
                  return;
              }
              b = b.next;
          }
          a = a.next;
      } while (a !== start);
  }
  
  // link every hole into the outer loop, producing a single-ring polygon without holes
  function eliminateHoles(data, holeIndices, outerNode, dim) {
      var queue = [],
          i, len, start, end, list;
  
      for (i = 0, len = holeIndices.length; i < len; i++) {
          start = holeIndices[i] * dim;
          end = i < len - 1 ? holeIndices[i + 1] * dim : data.length;
          list = linkedList(data, start, end, dim, false);
          if (list === list.next) list.steiner = true;
          queue.push(getLeftmost(list));
      }
  
      queue.sort(compareX);
  
      // process holes from left to right
      for (i = 0; i < queue.length; i++) {
          eliminateHole(queue[i], outerNode);
          outerNode = filterPoints(outerNode, outerNode.next);
      }
  
      return outerNode;
  }
  
  function compareX(a, b) {
      return a.x - b.x;
  }
  
  // find a bridge between vertices that connects hole with an outer ring and and link it
  function eliminateHole(hole, outerNode) {
      outerNode = findHoleBridge(hole, outerNode);
      if (outerNode) {
          var b = splitPolygon(outerNode, hole);
  
          // filter collinear points around the cuts
          filterPoints(outerNode, outerNode.next);
          filterPoints(b, b.next);
      }
  }
  
  // David Eberly's algorithm for finding a bridge between hole and outer polygon
  function findHoleBridge(hole, outerNode) {
      var p = outerNode,
          hx = hole.x,
          hy = hole.y,
          qx = -Infinity,
          m;
  
      // find a segment intersected by a ray from the hole's leftmost point to the left;
      // segment's endpoint with lesser x will be potential connection point
      do {
          if (hy <= p.y && hy >= p.next.y && p.next.y !== p.y) {
              var x = p.x + (hy - p.y) * (p.next.x - p.x) / (p.next.y - p.y);
              if (x <= hx && x > qx) {
                  qx = x;
                  if (x === hx) {
                      if (hy === p.y) return p;
                      if (hy === p.next.y) return p.next;
                  }
                  m = p.x < p.next.x ? p : p.next;
              }
          }
          p = p.next;
      } while (p !== outerNode);
  
      if (!m) return null;
  
      if (hx === qx) return m; // hole touches outer segment; pick leftmost endpoint
  
      // look for points inside the triangle of hole point, segment intersection and endpoint;
      // if there are no points found, we have a valid connection;
      // otherwise choose the point of the minimum angle with the ray as connection point
  
      var stop = m,
          mx = m.x,
          my = m.y,
          tanMin = Infinity,
          tan;
  
      p = m;
  
      do {
          if (hx >= p.x && p.x >= mx && hx !== p.x &&
                  pointInTriangle(hy < my ? hx : qx, hy, mx, my, hy < my ? qx : hx, hy, p.x, p.y)) {
  
              tan = Math.abs(hy - p.y) / (hx - p.x); // tangential
  
              if (locallyInside(p, hole) &&
                  (tan < tanMin || (tan === tanMin && (p.x > m.x || (p.x === m.x && sectorContainsSector(m, p)))))) {
                  m = p;
                  tanMin = tan;
              }
          }
  
          p = p.next;
      } while (p !== stop);
  
      return m;
  }
  
  // whether sector in vertex m contains sector in vertex p in the same coordinates
  function sectorContainsSector(m, p) {
      return area(m.prev, m, p.prev) < 0 && area(p.next, m, m.next) < 0;
  }
  
  // interlink polygon nodes in z-order
  function indexCurve(start, minX, minY, invSize) {
      var p = start;
      do {
          if (p.z === null) p.z = zOrder(p.x, p.y, minX, minY, invSize);
          p.prevZ = p.prev;
          p.nextZ = p.next;
          p = p.next;
      } while (p !== start);
  
      p.prevZ.nextZ = null;
      p.prevZ = null;
  
      sortLinked(p);
  }
  
  // Simon Tatham's linked list merge sort algorithm
  // http://www.chiark.greenend.org.uk/~sgtatham/algorithms/listsort.html
  function sortLinked(list) {
      var i, p, q, e, tail, numMerges, pSize, qSize,
          inSize = 1;
  
      do {
          p = list;
          list = null;
          tail = null;
          numMerges = 0;
  
          while (p) {
              numMerges++;
              q = p;
              pSize = 0;
              for (i = 0; i < inSize; i++) {
                  pSize++;
                  q = q.nextZ;
                  if (!q) break;
              }
              qSize = inSize;
  
              while (pSize > 0 || (qSize > 0 && q)) {
  
                  if (pSize !== 0 && (qSize === 0 || !q || p.z <= q.z)) {
                      e = p;
                      p = p.nextZ;
                      pSize--;
                  } else {
                      e = q;
                      q = q.nextZ;
                      qSize--;
                  }
  
                  if (tail) tail.nextZ = e;
                  else list = e;
  
                  e.prevZ = tail;
                  tail = e;
              }
  
              p = q;
          }
  
          tail.nextZ = null;
          inSize *= 2;
  
      } while (numMerges > 1);
  
      return list;
  }
  
  // z-order of a point given coords and inverse of the longer side of data bbox
  function zOrder(x, y, minX, minY, invSize) {
      // coords are transformed into non-negative 15-bit integer range
      x = 32767 * (x - minX) * invSize;
      y = 32767 * (y - minY) * invSize;
  
      x = (x | (x << 8)) & 0x00FF00FF;
      x = (x | (x << 4)) & 0x0F0F0F0F;
      x = (x | (x << 2)) & 0x33333333;
      x = (x | (x << 1)) & 0x55555555;
  
      y = (y | (y << 8)) & 0x00FF00FF;
      y = (y | (y << 4)) & 0x0F0F0F0F;
      y = (y | (y << 2)) & 0x33333333;
      y = (y | (y << 1)) & 0x55555555;
  
      return x | (y << 1);
  }
  
  // find the leftmost node of a polygon ring
  function getLeftmost(start) {
      var p = start,
          leftmost = start;
      do {
          if (p.x < leftmost.x || (p.x === leftmost.x && p.y < leftmost.y)) leftmost = p;
          p = p.next;
      } while (p !== start);
  
      return leftmost;
  }
  
  // check if a point lies within a convex triangle
  function pointInTriangle(ax, ay, bx, by, cx, cy, px, py) {
      return (cx - px) * (ay - py) - (ax - px) * (cy - py) >= 0 &&
             (ax - px) * (by - py) - (bx - px) * (ay - py) >= 0 &&
             (bx - px) * (cy - py) - (cx - px) * (by - py) >= 0;
  }
  
  // check if a diagonal between two polygon nodes is valid (lies in polygon interior)
  function isValidDiagonal(a, b) {
      return a.next.i !== b.i && a.prev.i !== b.i && !intersectsPolygon(a, b) && // dones't intersect other edges
             (locallyInside(a, b) && locallyInside(b, a) && middleInside(a, b) && // locally visible
              (area(a.prev, a, b.prev) || area(a, b.prev, b)) || // does not create opposite-facing sectors
              equals(a, b) && area(a.prev, a, a.next) > 0 && area(b.prev, b, b.next) > 0); // special zero-length case
  }
  
  // signed area of a triangle
  function area(p, q, r) {
      return (q.y - p.y) * (r.x - q.x) - (q.x - p.x) * (r.y - q.y);
  }
  
  // check if two points are equal
  function equals(p1, p2) {
      return p1.x === p2.x && p1.y === p2.y;
  }
  
  // check if two segments intersect
  function intersects(p1, q1, p2, q2) {
      var o1 = sign(area(p1, q1, p2));
      var o2 = sign(area(p1, q1, q2));
      var o3 = sign(area(p2, q2, p1));
      var o4 = sign(area(p2, q2, q1));
  
      if (o1 !== o2 && o3 !== o4) return true; // general case
  
      if (o1 === 0 && onSegment(p1, p2, q1)) return true; // p1, q1 and p2 are collinear and p2 lies on p1q1
      if (o2 === 0 && onSegment(p1, q2, q1)) return true; // p1, q1 and q2 are collinear and q2 lies on p1q1
      if (o3 === 0 && onSegment(p2, p1, q2)) return true; // p2, q2 and p1 are collinear and p1 lies on p2q2
      if (o4 === 0 && onSegment(p2, q1, q2)) return true; // p2, q2 and q1 are collinear and q1 lies on p2q2
  
      return false;
  }
  
  // for collinear points p, q, r, check if point q lies on segment pr
  function onSegment(p, q, r) {
      return q.x <= Math.max(p.x, r.x) && q.x >= Math.min(p.x, r.x) && q.y <= Math.max(p.y, r.y) && q.y >= Math.min(p.y, r.y);
  }
  
  function sign(num) {
      return num > 0 ? 1 : num < 0 ? -1 : 0;
  }
  
  // check if a polygon diagonal intersects any polygon segments
  function intersectsPolygon(a, b) {
      var p = a;
      do {
          if (p.i !== a.i && p.next.i !== a.i && p.i !== b.i && p.next.i !== b.i &&
                  intersects(p, p.next, a, b)) return true;
          p = p.next;
      } while (p !== a);
  
      return false;
  }
  
  // check if a polygon diagonal is locally inside the polygon
  function locallyInside(a, b) {
      return area(a.prev, a, a.next) < 0 ?
          area(a, b, a.next) >= 0 && area(a, a.prev, b) >= 0 :
          area(a, b, a.prev) < 0 || area(a, a.next, b) < 0;
  }
  
  // check if the middle point of a polygon diagonal is inside the polygon
  function middleInside(a, b) {
      var p = a,
          inside = false,
          px = (a.x + b.x) / 2,
          py = (a.y + b.y) / 2;
      do {
          if (((p.y > py) !== (p.next.y > py)) && p.next.y !== p.y &&
                  (px < (p.next.x - p.x) * (py - p.y) / (p.next.y - p.y) + p.x))
              inside = !inside;
          p = p.next;
      } while (p !== a);
  
      return inside;
  }
  
  // link two polygon vertices with a bridge; if the vertices belong to the same ring, it splits polygon into two;
  // if one belongs to the outer ring and another to a hole, it merges it into a single ring
  function splitPolygon(a, b) {
      var a2 = new Node(a.i, a.x, a.y),
          b2 = new Node(b.i, b.x, b.y),
          an = a.next,
          bp = b.prev;
  
      a.next = b;
      b.prev = a;
  
      a2.next = an;
      an.prev = a2;
  
      b2.next = a2;
      a2.prev = b2;
  
      bp.next = b2;
      b2.prev = bp;
  
      return b2;
  }
  
  // create a node and optionally link it with previous one (in a circular doubly linked list)
  function insertNode(i, x, y, last) {
      var p = new Node(i, x, y);
  
      if (!last) {
          p.prev = p;
          p.next = p;
  
      } else {
          p.next = last.next;
          p.prev = last;
          last.next.prev = p;
          last.next = p;
      }
      return p;
  }
  
  function removeNode(p) {
      p.next.prev = p.prev;
      p.prev.next = p.next;
  
      if (p.prevZ) p.prevZ.nextZ = p.nextZ;
      if (p.nextZ) p.nextZ.prevZ = p.prevZ;
  }
  
  function Node(i, x, y) {
      // vertex index in coordinates array
      this.i = i;
  
      // vertex coordinates
      this.x = x;
      this.y = y;
  
      // previous and next vertex nodes in a polygon ring
      this.prev = null;
      this.next = null;
  
      // z-order curve value
      this.z = null;
  
      // previous and next nodes in z-order
      this.prevZ = null;
      this.nextZ = null;
  
      // indicates whether this is a steiner point
      this.steiner = false;
  }
  
  // return a percentage difference between the polygon area and its triangulation area;
  // used to verify correctness of triangulation
  earcut.deviation = function (data, holeIndices, dim, triangles) {
      var hasHoles = holeIndices && holeIndices.length;
      var outerLen = hasHoles ? holeIndices[0] * dim : data.length;
  
      var polygonArea = Math.abs(signedArea(data, 0, outerLen, dim));
      if (hasHoles) {
          for (var i = 0, len = holeIndices.length; i < len; i++) {
              var start = holeIndices[i] * dim;
              var end = i < len - 1 ? holeIndices[i + 1] * dim : data.length;
              polygonArea -= Math.abs(signedArea(data, start, end, dim));
          }
      }
  
      var trianglesArea = 0;
      for (i = 0; i < triangles.length; i += 3) {
          var a = triangles[i] * dim;
          var b = triangles[i + 1] * dim;
          var c = triangles[i + 2] * dim;
          trianglesArea += Math.abs(
              (data[a] - data[c]) * (data[b + 1] - data[a + 1]) -
              (data[a] - data[b]) * (data[c + 1] - data[a + 1]));
      }
  
      return polygonArea === 0 && trianglesArea === 0 ? 0 :
          Math.abs((trianglesArea - polygonArea) / polygonArea);
  };
  
  function signedArea(data, start, end, dim) {
      var sum = 0;
      for (var i = start, j = end - dim; i < end; i += dim) {
          sum += (data[j] - data[i]) * (data[i + 1] + data[j + 1]);
          j = i;
      }
      return sum;
  }
  
  // turn a polygon in a multi-dimensional array form (e.g. as in GeoJSON) into a form Earcut accepts
  earcut.flatten = function (data) {
      var dim = data[0][0].length,
          result = {vertices: [], holes: [], dimensions: dim},
          holeIndex = 0;
  
      for (var i = 0; i < data.length; i++) {
          for (var j = 0; j < data[i].length; j++) {
              for (var d = 0; d < dim; d++) result.vertices.push(data[i][j][d]);
          }
          if (i > 0) {
              holeIndex += data[i - 1].length;
              result.holes.push(holeIndex);
          }
      }
      return result;
  };
  
  module.exports = earcut;
  