text: /*global define*/
  define([
          '../Core/defaultValue',
          '../Core/defined',
          '../Core/defineProperties',
          '../Core/DeveloperError',
          '../Core/Event',
          './createMaterialPropertyDescriptor',
          './createPropertyDescriptor'
      ], function(
          defaultValue,
          defined,
          defineProperties,
          DeveloperError,
          Event,
          createMaterialPropertyDescriptor,
          createPropertyDescriptor) {
      "use strict";
  
      /**
       * Describes a polyline defined as a line strip. The first two positions define a line segment,
       * and each additional position defines a line segment from the previous position. The segments
       * can be linear connected points or great arcs.
       *
       * @alias PolylineGraphics
       * @constructor
       *
       * @param {Object} [options] Object with the following properties:
       * @param {Property} [options.positions] A Property specifying the array of {@link Cartesian3} positions that define the line strip.
       * @param {Property} [options.followSurface=true] A boolean Property specifying whether the line segments should be great arcs or linearly connected.
       * @param {Property} [options.width=1.0] A numeric Property specifying the width in pixels.
       * @param {Property} [options.show=true] A boolean Property specifying the visibility of the polyline.
       * @param {MaterialProperty} [options.material=Color.WHITE] A Property specifying the material used to draw the polyline.
       * @param {Property} [options.granularity=Cesium.Math.RADIANS_PER_DEGREE] A numeric Property specifying the angular distance between each latitude and longitude if followSurface is true.
       *
       * @see Entity
       * @demo {@link http://cesiumjs.org/Cesium/Apps/Sandcastle/index.html?src=Polyline.html|Cesium Sandcastle Polyline Demo}
       */
      function PolylineGraphics(options) {
          this._show = undefined;
          this._showSubscription = undefined;
          this._material = undefined;
          this._materialSubscription = undefined;
          this._positions = undefined;
          this._positionsSubscription = undefined;
          this._followSurface = undefined;
          this._followSurfaceSubscription = undefined;
          this._granularity = undefined;
          this._granularitySubscription = undefined;
          this._widthSubscription = undefined;
          this._width = undefined;
          this._widthSubscription = undefined;
          this._definitionChanged = new Event();
  
          this.merge(defaultValue(options, defaultValue.EMPTY_OBJECT));
      }
  
      defineProperties(PolylineGraphics.prototype, {
          /**
           * Gets the event that is raised whenever a property or sub-property is changed or modified.
           * @memberof PolylineGraphics.prototype
           *
           * @type {Event}
           * @readonly
           */
          definitionChanged : {
              get : function() {
                  return this._definitionChanged;
              }
          },
  
          /**
           * Gets or sets the boolean Property specifying the visibility of the polyline.
           * @memberof PolylineGraphics.prototype
           * @type {Property}
           * @default true
           */
          show : createPropertyDescriptor('show'),
  
          /**
           * Gets or sets the Property specifying the material used to draw the polyline.
           * @memberof PolylineGraphics.prototype
           * @type {MaterialProperty}
           * @default Color.WHITE
           */
          material : createMaterialPropertyDescriptor('material'),
  
          /**
           * Gets or sets the Property specifying the array of {@link Cartesian3}
           * positions that define the line strip.
           * @memberof PolylineGraphics.prototype
           * @type {Property}
           */
          positions : createPropertyDescriptor('positions'),
  
          /**
           * Gets or sets the numeric Property specifying the width in pixels.
           * @memberof PolylineGraphics.prototype
           * @type {Property}
           * @default 1.0
           */
          width : createPropertyDescriptor('width'),
  
          /**
           * Gets or sets the boolean Property specifying whether the line segments
           * should be great arcs or linearly connected.
           * @memberof PolylineGraphics.prototype
           * @type {Property}
           * @default true
           */
          followSurface : createPropertyDescriptor('followSurface'),
  
          /**
           * Gets or sets the numeric Property specifying the angular distance between each latitude and longitude if followSurface is true.
           * @memberof PolylineGraphics.prototype
           * @type {Property}
           * @default Cesium.Math.RADIANS_PER_DEGREE
           */
          granularity : createPropertyDescriptor('granularity')
      });
  
      /**
       * Duplicates this instance.
       *
       * @param {PolylineGraphics} [result] The object onto which to store the result.
       * @returns {PolylineGraphics} The modified result parameter or a new instance if one was not provided.
       */
      PolylineGraphics.prototype.clone = function(result) {
          if (!defined(result)) {
              return new PolylineGraphics(this);
          }
          result.show = this.show;
          result.material = this.material;
          result.positions = this.positions;
          result.width = this.width;
          result.followSurface = this.followSurface;
          result.granularity = this.granularity;
          return result;
      };
  
      /**
       * Assigns each unassigned property on this object to the value
       * of the same property on the provided source object.
       *
       * @param {PolylineGraphics} source The object to be merged into this object.
       */
      PolylineGraphics.prototype.merge = function(source) {
          //>>includeStart('debug', pragmas.debug);
          if (!defined(source)) {
              throw new DeveloperError('source is required.');
          }
          //>>includeEnd('debug');
  
          this.show = defaultValue(this.show, source.show);
          this.material = defaultValue(this.material, source.material);
          this.positions = defaultValue(this.positions, source.positions);
          this.width = defaultValue(this.width, source.width);
          this.followSurface = defaultValue(this.followSurface, source.followSurface);
          this.granularity = defaultValue(this.granularity, source.granularity);
      };
  
      return PolylineGraphics;
  });
  