text: /*global define*/
  define([
          './BoundingSphere',
          './Cartesian3',
          './Color',
          './ComponentDatatype',
          './defaultValue',
          './defined',
          './DeveloperError',
          './Ellipsoid',
          './Geometry',
          './GeometryAttribute',
          './GeometryAttributes',
          './GeometryType',
          './IndexDatatype',
          './Math',
          './PolylinePipeline',
          './PrimitiveType',
          './VertexFormat'
      ], function(
          BoundingSphere,
          Cartesian3,
          Color,
          ComponentDatatype,
          defaultValue,
          defined,
          DeveloperError,
          Ellipsoid,
          Geometry,
          GeometryAttribute,
          GeometryAttributes,
          GeometryType,
          IndexDatatype,
          CesiumMath,
          PolylinePipeline,
          PrimitiveType,
          VertexFormat) {
      "use strict";
  
      var scratchInterpolateColorsArray = [];
  
      function interpolateColors(p0, p1, color0, color1, numPoints) {
          var colors = scratchInterpolateColorsArray;
          colors.length = numPoints;
          var i;
  
          var r0 = color0.red;
          var g0 = color0.green;
          var b0 = color0.blue;
          var a0 = color0.alpha;
  
          var r1 = color1.red;
          var g1 = color1.green;
          var b1 = color1.blue;
          var a1 = color1.alpha;
  
          if (Color.equals(color0, color1)) {
              for (i = 0; i < numPoints; i++) {
                  colors[i] = Color.clone(color0);
              }
              return colors;
          }
  
          var redPerVertex = (r1 - r0) / numPoints;
          var greenPerVertex = (g1 - g0) / numPoints;
          var bluePerVertex = (b1 - b0) / numPoints;
          var alphaPerVertex = (a1 - a0) / numPoints;
  
          for (i = 0; i < numPoints; i++) {
              colors[i] = new Color(r0 + i * redPerVertex, g0 + i * greenPerVertex, b0 + i * bluePerVertex, a0 + i * alphaPerVertex);
          }
  
          return colors;
      }
  
      /**
       * A description of a polyline modeled 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 polyline is capable of
       * displaying with a material.
       *
       * @alias PolylineGeometry
       * @constructor
       *
       * @param {Object} options Object with the following properties:
       * @param {Cartesian3[]} options.positions An array of {@link Cartesian3} defining the positions in the polyline as a line strip.
       * @param {Number} [options.width=1.0] The width in pixels.
       * @param {Color[]} [options.colors] An Array of {@link Color} defining the per vertex or per segment colors.
       * @param {Boolean} [options.colorsPerVertex=false] A boolean that determines whether the colors will be flat across each segment of the line or interpolated across the vertices.
       * @param {Boolean} [options.followSurface=true] A boolean that determines whether positions will be adjusted to the surface of the ellipsoid via a great arc.
       * @param {Number} [options.granularity=CesiumMath.RADIANS_PER_DEGREE] The distance, in radians, between each latitude and longitude if options.followSurface=true. Determines the number of positions in the buffer.
       * @param {Ellipsoid} [options.ellipsoid=Ellipsoid.WGS84] The ellipsoid to be used as a reference.
       *
       * @exception {DeveloperError} At least two positions are required.
       * @exception {DeveloperError} width must be greater than or equal to one.
       * @exception {DeveloperError} colors has an invalid length.
       *
       * @see PolylineGeometry#createGeometry
       *
       * @demo {@link http://cesiumjs.org/Cesium/Apps/Sandcastle/index.html?src=Polyline.html|Cesium Sandcastle Polyline Demo}
       *
       * @example
       * // A polyline with two connected line segments
       * var polyline = new Cesium.PolylineGeometry({
       *   positions : Cesium.Cartesian3.fromDegreesArray([
       *     0.0, 0.0,
       *     5.0, 0.0,
       *     5.0, 5.0
       *   ]),
       *   width : 10.0
       * });
       * var geometry = Cesium.PolylineGeometry.createGeometry(polyline);
       */
      var PolylineGeometry = function(options) {
          options = defaultValue(options, defaultValue.EMPTY_OBJECT);
          var positions = options.positions;
          var colors = options.colors;
          var width = defaultValue(options.width, 1.0);
          var colorsPerVertex = defaultValue(options.colorsPerVertex, false);
  
          //>>includeStart('debug', pragmas.debug);
          if ((!defined(positions)) || (positions.length < 2)) {
              throw new DeveloperError('At least two positions are required.');
          }
          if (width < 1.0) {
              throw new DeveloperError('width must be greater than or equal to one.');
          }
          if (defined(colors) && ((colorsPerVertex && colors.length < positions.length) || (!colorsPerVertex && colors.length < positions.length - 1))) {
              throw new DeveloperError('colors has an invalid length.');
          }
          //>>includeEnd('debug');
  
          this._positions = positions;
          this._colors = colors;
          this._width = width;
          this._colorsPerVertex = colorsPerVertex;
          this._vertexFormat = VertexFormat.clone(defaultValue(options.vertexFormat, VertexFormat.DEFAULT));
          this._followSurface = defaultValue(options.followSurface, true);
          this._granularity = defaultValue(options.granularity, CesiumMath.RADIANS_PER_DEGREE);
          this._ellipsoid = Ellipsoid.clone(defaultValue(options.ellipsoid, Ellipsoid.WGS84));
          this._workerName = 'createPolylineGeometry';
  
          var numComponents = 1 + positions.length * Cartesian3.packedLength;
          numComponents += defined(colors) ? 1 + colors.length * Color.packedLength : 1;
  
          /**
           * The number of elements used to pack the object into an array.
           * @type {Number}
           */
          this.packedLength = numComponents + Ellipsoid.packedLength + VertexFormat.packedLength + 4;
      };
  
      /**
       * Stores the provided instance into the provided array.
       * @function
       *
       * @param {PolylineGeometry} value The value to pack.
       * @param {Number[]} array The array to pack into.
       * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
       */
      PolylineGeometry.pack = function(value, array, startingIndex) {
          //>>includeStart('debug', pragmas.debug);
          if (!defined(value)) {
              throw new DeveloperError('value is required');
          }
          if (!defined(array)) {
              throw new DeveloperError('array is required');
          }
          //>>includeEnd('debug');
  
          startingIndex = defaultValue(startingIndex, 0);
  
          var i;
  
          var positions = value._positions;
          var length = positions.length;
          array[startingIndex++] = length;
  
          for (i = 0; i < length; ++i, startingIndex += Cartesian3.packedLength) {
              Cartesian3.pack(positions[i], array, startingIndex);
          }
  
          var colors = value._colors;
          length = defined(colors) ? colors.length : 0.0;
          array[startingIndex++] = length;
  
          for (i = 0; i < length; ++i, startingIndex += Color.packedLength) {
              Color.pack(colors[i], array, startingIndex);
          }
  
          Ellipsoid.pack(value._ellipsoid, array, startingIndex);
          startingIndex += Ellipsoid.packedLength;
  
          VertexFormat.pack(value._vertexFormat, array, startingIndex);
          startingIndex += VertexFormat.packedLength;
  
          array[startingIndex++] = value._width;
          array[startingIndex++] = value._colorsPerVertex ? 1.0 : 0.0;
          array[startingIndex++] = value._followSurface ? 1.0 : 0.0;
          array[startingIndex]   = value._granularity;
      };
  
      var scratchEllipsoid = Ellipsoid.clone(Ellipsoid.UNIT_SPHERE);
      var scratchVertexFormat = new VertexFormat();
      var scratchOptions = {
          positions : undefined,
          colors : undefined,
          ellipsoid : scratchEllipsoid,
          vertexFormat : scratchVertexFormat,
          width : undefined,
          colorsPerVertex : undefined,
          followSurface : undefined,
          granularity : undefined
      };
  
      /**
       * Retrieves an instance from a packed array.
       *
       * @param {Number[]} array The packed array.
       * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
       * @param {PolylineGeometry} [result] The object into which to store the result.
       * @returns {PolylineGeometry} The modified result parameter or a new PolylineGeometry instance if one was not provided.
       */
      PolylineGeometry.unpack = function(array, startingIndex, result) {
          //>>includeStart('debug', pragmas.debug);
          if (!defined(array)) {
              throw new DeveloperError('array is required');
          }
          //>>includeEnd('debug');
  
          startingIndex = defaultValue(startingIndex, 0);
  
          var i;
  
          var length = array[startingIndex++];
          var positions = new Array(length);
  
          for (i = 0; i < length; ++i, startingIndex += Cartesian3.packedLength) {
              positions[i] = Cartesian3.unpack(array, startingIndex);
          }
  
          length = array[startingIndex++];
          var colors = length > 0 ? new Array(length) : undefined;
  
          for (i = 0; i < length; ++i, startingIndex += Color.packedLength) {
              colors[i] = Color.unpack(array, startingIndex);
          }
  
          var ellipsoid = Ellipsoid.unpack(array, startingIndex, scratchEllipsoid);
          startingIndex += Ellipsoid.packedLength;
  
          var vertexFormat = VertexFormat.unpack(array, startingIndex, scratchVertexFormat);
          startingIndex += VertexFormat.packedLength;
  
          var width = array[startingIndex++];
          var colorsPerVertex = array[startingIndex++] === 1.0;
          var followSurface = array[startingIndex++] === 1.0;
          var granularity = array[startingIndex];
  
          if (!defined(result)) {
              scratchOptions.positions = positions;
              scratchOptions.colors = colors;
              scratchOptions.width = width;
              scratchOptions.colorsPerVertex = colorsPerVertex;
              scratchOptions.followSurface = followSurface;
              scratchOptions.granularity = granularity;
              return new PolylineGeometry(scratchOptions);
          }
  
          result._positions = positions;
          result._colors = colors;
          result._ellipsoid = Ellipsoid.clone(ellipsoid, result._ellipsoid);
          result._vertexFormat = VertexFormat.clone(vertexFormat, result._vertexFormat);
          result._width = width;
          result._colorsPerVertex = colorsPerVertex;
          result._followSurface = followSurface;
          result._granularity = granularity;
  
          return result;
      };
  
      var scratchCartesian3 = new Cartesian3();
      var scratchPosition = new Cartesian3();
      var scratchPrevPosition = new Cartesian3();
      var scratchNextPosition = new Cartesian3();
  
      /**
       * Computes the geometric representation of a polyline, including its vertices, indices, and a bounding sphere.
       *
       * @param {PolylineGeometry} polylineGeometry A description of the polyline.
       * @returns {Geometry|undefined} The computed vertices and indices.
       */
      PolylineGeometry.createGeometry = function(polylineGeometry) {
          var width = polylineGeometry._width;
          var vertexFormat = polylineGeometry._vertexFormat;
          var colors = polylineGeometry._colors;
          var colorsPerVertex = polylineGeometry._colorsPerVertex;
          var followSurface = polylineGeometry._followSurface;
          var granularity = polylineGeometry._granularity;
          var ellipsoid = polylineGeometry._ellipsoid;
  
          var minDistance = CesiumMath.chordLength(granularity, ellipsoid.maximumRadius);
  
          var i;
          var j;
          var k;
  
          var positions = PolylinePipeline.removeDuplicates(polylineGeometry._positions);
  
          var positionsLength = positions.length;
          if (positionsLength < 2) {
              return undefined;
          }
  
          if (followSurface) {
              var heights = PolylinePipeline.extractHeights(positions, ellipsoid);
  
              if (defined(colors)) {
                  var colorLength = 1;
                  for (i = 0; i < positionsLength - 1; ++i) {
                      colorLength += PolylinePipeline.numberOfPoints(positions[i], positions[i+1], minDistance);
                  }
  
                  var newColors = new Array(colorLength);
                  var newColorIndex = 0;
  
                  for (i = 0; i < positionsLength - 1; ++i) {
                      var p0 = positions[i];
                      var p1 = positions[i+1];
                      var c0 = colors[i];
  
                      var numColors = PolylinePipeline.numberOfPoints(p0, p1, minDistance);
                      if (colorsPerVertex && i < colorLength) {
                          var c1 = colors[i+1];
                          var interpolatedColors = interpolateColors(p0, p1, c0, c1, numColors);
                          var interpolatedColorsLength = interpolatedColors.length;
                          for (j = 0; j < interpolatedColorsLength; ++j) {
                              newColors[newColorIndex++] = interpolatedColors[j];
                          }
                      } else {
                          for (j = 0; j < numColors; ++j) {
                              newColors[newColorIndex++] = Color.clone(c0);
                          }
                      }
                  }
  
                  newColors[newColorIndex] = Color.clone(colors[colors.length-1]);
                  colors = newColors;
  
                  scratchInterpolateColorsArray.length = 0;
              }
  
              positions = PolylinePipeline.generateCartesianArc({
                  positions: positions,
                  minDistance: minDistance,
                  ellipsoid: ellipsoid,
                  height: heights
              });
          }
  
          positionsLength = positions.length;
          var size = positionsLength * 4.0 - 4.0;
  
          var finalPositions = new Float64Array(size * 3);
          var prevPositions = new Float64Array(size * 3);
          var nextPositions = new Float64Array(size * 3);
          var expandAndWidth = new Float32Array(size * 2);
          var st = vertexFormat.st ? new Float32Array(size * 2) : undefined;
          var finalColors = defined(colors) ? new Uint8Array(size * 4) : undefined;
  
          var positionIndex = 0;
          var expandAndWidthIndex = 0;
          var stIndex = 0;
          var colorIndex = 0;
  
          var segmentLength;
          var segmentIndex = 0;
          var count = 0;
          var position;
  
          for (j = 0; j < positionsLength; ++j) {
              if (j === 0) {
                  position = scratchCartesian3;
                  Cartesian3.subtract(positions[0], positions[1], position);
                  Cartesian3.add(positions[0], position, position);
              } else {
                  position = positions[j - 1];
              }
  
              Cartesian3.clone(position, scratchPrevPosition);
              Cartesian3.clone(positions[j], scratchPosition);
  
              if (j === positionsLength - 1) {
                  position = scratchCartesian3;
                  Cartesian3.subtract(positions[positionsLength - 1], positions[positionsLength - 2], position);
                  Cartesian3.add(positions[positionsLength - 1], position, position);
              } else {
                  position = positions[j + 1];
              }
  
              Cartesian3.clone(position, scratchNextPosition);
  
              var color0, color1;
              if (defined(finalColors)) {
                  if (j !== 0 && !colorsPerVertex) {
                      color0 = colors[j - 1];
                  } else {
                      color0 = colors[j];
                  }
  
                  if (j !== positionsLength - 1) {
                      color1 = colors[j];
                  }
              }
  
              var startK = j === 0 ? 2 : 0;
              var endK = j === positionsLength - 1 ? 2 : 4;
  
              for (k = startK; k < endK; ++k) {
                  Cartesian3.pack(scratchPosition, finalPositions, positionIndex);
                  Cartesian3.pack(scratchPrevPosition, prevPositions, positionIndex);
                  Cartesian3.pack(scratchNextPosition, nextPositions, positionIndex);
                  positionIndex += 3;
  
                  var direction = (k - 2 < 0) ? -1.0 : 1.0;
                  expandAndWidth[expandAndWidthIndex++] = 2 * (k % 2) - 1;       // expand direction
                  expandAndWidth[expandAndWidthIndex++] = direction * width;
  
                  if (vertexFormat.st) {
                      st[stIndex++] = j / (positionsLength - 1);
                      st[stIndex++] = Math.max(expandAndWidth[expandAndWidthIndex - 2], 0.0);
                  }
  
                  if (defined(finalColors)) {
                      var color = (k < 2) ? color0 : color1;
  
                      finalColors[colorIndex++] = Color.floatToByte(color.red);
                      finalColors[colorIndex++] = Color.floatToByte(color.green);
                      finalColors[colorIndex++] = Color.floatToByte(color.blue);
                      finalColors[colorIndex++] = Color.floatToByte(color.alpha);
                  }
              }
          }
  
          var attributes = new GeometryAttributes();
  
          attributes.position = new GeometryAttribute({
              componentDatatype : ComponentDatatype.DOUBLE,
              componentsPerAttribute : 3,
              values : finalPositions
          });
  
          attributes.prevPosition = new GeometryAttribute({
              componentDatatype : ComponentDatatype.DOUBLE,
              componentsPerAttribute : 3,
              values : prevPositions
          });
  
          attributes.nextPosition = new GeometryAttribute({
              componentDatatype : ComponentDatatype.DOUBLE,
              componentsPerAttribute : 3,
              values : nextPositions
          });
  
          attributes.expandAndWidth = new GeometryAttribute({
              componentDatatype : ComponentDatatype.FLOAT,
              componentsPerAttribute : 2,
              values : expandAndWidth
          });
  
          if (vertexFormat.st) {
              attributes.st = new GeometryAttribute({
                  componentDatatype : ComponentDatatype.FLOAT,
                  componentsPerAttribute : 2,
                  values : st
              });
          }
  
          if (defined(finalColors)) {
              attributes.color = new GeometryAttribute({
                  componentDatatype : ComponentDatatype.UNSIGNED_BYTE,
                  componentsPerAttribute : 4,
                  values : finalColors,
                  normalize : true
              });
          }
  
          var indices = IndexDatatype.createTypedArray(size, positionsLength * 6 - 6);
          var index = 0;
          var indicesIndex = 0;
          var length = positionsLength - 1.0;
          for (j = 0; j < length; ++j) {
              indices[indicesIndex++] = index;
              indices[indicesIndex++] = index + 2;
              indices[indicesIndex++] = index + 1;
  
              indices[indicesIndex++] = index + 1;
              indices[indicesIndex++] = index + 2;
              indices[indicesIndex++] = index + 3;
  
              index += 4;
          }
  
          return new Geometry({
              attributes : attributes,
              indices : indices,
              primitiveType : PrimitiveType.TRIANGLES,
              boundingSphere : BoundingSphere.fromPoints(positions),
              geometryType : GeometryType.POLYLINES
          });
      };
  
      return PolylineGeometry;
  });
  