ShuoHuang/public/SuperMap/Cesium/Workers/PolygonGeometryLibrary-073be5ba.js

/**
 * Cesium - https://github.com/AnalyticalGraphicsInc/cesium
 *
 * Copyright 2011-2017 Cesium Contributors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * Columbus View (Pat. Pend.)
 *
 * Portions licensed separately.
 * See https://github.com/AnalyticalGraphicsInc/cesium/blob/master/LICENSE.md for full licensing details.
 */
define(['exports', './when-8d13db60', './Math-61ede240', './Cartographic-fe4be337', './Cartesian2-85064f09', './BoundingSphere-775c5788', './ComponentDatatype-5862616f', './GeometryAttribute-91704ebb', './PrimitiveType-97893bc7', './Transforms-b2e71640', './GeometryAttributes-aacecde6', './GeometryPipeline-f95a0a6f', './IndexDatatype-9435b55f', './arrayRemoveDuplicates-f0b089b1', './ArcType-66bc286a', './EllipsoidRhumbLine-f161e674', './PolygonPipeline-6a35d737'], function (exports, when, _Math, Cartographic, Cartesian2, BoundingSphere, ComponentDatatype, GeometryAttribute, PrimitiveType, Transforms, GeometryAttributes, GeometryPipeline, IndexDatatype, arrayRemoveDuplicates, ArcType, EllipsoidRhumbLine, PolygonPipeline) { 'use strict';

    /**
         * A queue that can enqueue items at the end, and dequeue items from the front.
         *
         * @alias Queue
         * @constructor
         */
        function Queue() {
            this._array = [];
            this._offset = 0;
            this._length = 0;
        }

        Object.defineProperties(Queue.prototype, {
            /**
             * The length of the queue.
             *
             * @memberof Queue.prototype
             *
             * @type {Number}
             * @readonly
             */
            length : {
                get : function() {
                    return this._length;
                }
            }
        });

        /**
         * Enqueues the specified item.
         *
         * @param {*} item The item to enqueue.
         */
        Queue.prototype.enqueue = function(item) {
            this._array.push(item);
            this._length++;
        };

        /**
         * Dequeues an item.  Returns undefined if the queue is empty.
         *
         * @returns {*} The the dequeued item.
         */
        Queue.prototype.dequeue = function() {
            if (this._length === 0) {
                return undefined;
            }

            var array = this._array;
            var offset = this._offset;
            var item = array[offset];
            array[offset] = undefined;

            offset++;
            if ((offset > 10) && (offset * 2 > array.length)) {
                //compact array
                this._array = array.slice(offset);
                offset = 0;
            }

            this._offset = offset;
            this._length--;

            return item;
        };

        /**
         * Returns the item at the front of the queue.  Returns undefined if the queue is empty.
         *
         * @returns {*} The item at the front of the queue.
         */
        Queue.prototype.peek = function() {
            if (this._length === 0) {
                return undefined;
            }

            return this._array[this._offset];
        };

        /**
         * Check whether this queue contains the specified item.
         *
         * @param {*} item The item to search for.
         */
        Queue.prototype.contains = function(item) {
            return this._array.indexOf(item) !== -1;
        };

        /**
         * Remove all items from the queue.
         */
        Queue.prototype.clear = function() {
            this._array.length = this._offset = this._length = 0;
        };

        /**
         * Sort the items in the queue in-place.
         *
         * @param {Queue~Comparator} compareFunction A function that defines the sort order.
         */
        Queue.prototype.sort = function(compareFunction) {
            if (this._offset > 0) {
                //compact array
                this._array = this._array.slice(this._offset);
                this._offset = 0;
            }

            this._array.sort(compareFunction);
        };

    /**
         * @private
         */
        var PolygonGeometryLibrary = {};

        PolygonGeometryLibrary.computeHierarchyPackedLength = function(polygonHierarchy) {
            var numComponents = 0;
            var stack = [polygonHierarchy];
            while (stack.length > 0) {
                var hierarchy = stack.pop();
                if (!when.defined(hierarchy)) {
                    continue;
                }

                numComponents += 2;

                var positions = hierarchy.positions;
                var holes = hierarchy.holes;

                if (when.defined(positions)) {
                    numComponents += positions.length * Cartographic.Cartesian3.packedLength;
                }

                if (when.defined(holes)) {
                    var length = holes.length;
                    for (var i = 0; i < length; ++i) {
                        stack.push(holes[i]);
                    }
                }
            }

            return numComponents;
        };

        PolygonGeometryLibrary.packPolygonHierarchy = function(polygonHierarchy, array, startingIndex) {
            var stack = [polygonHierarchy];
            while (stack.length > 0) {
                var hierarchy = stack.pop();
                if (!when.defined(hierarchy)) {
                    continue;
                }

                var positions = hierarchy.positions;
                var holes = hierarchy.holes;

                array[startingIndex++] = when.defined(positions) ? positions.length : 0;
                array[startingIndex++] = when.defined(holes) ? holes.length : 0;

                if (when.defined(positions)) {
                    var positionsLength = positions.length;
                    for (var i = 0; i < positionsLength; ++i, startingIndex += 3) {
                        Cartographic.Cartesian3.pack(positions[i], array, startingIndex);
                    }
                }

                if (when.defined(holes)) {
                    var holesLength = holes.length;
                    for (var j = 0; j < holesLength; ++j) {
                        stack.push(holes[j]);
                    }
                }
            }

            return startingIndex;
        };

        PolygonGeometryLibrary.unpackPolygonHierarchy = function(array, startingIndex) {
            var positionsLength = array[startingIndex++];
            var holesLength = array[startingIndex++];

            var positions = new Array(positionsLength);
            var holes = holesLength > 0 ? new Array(holesLength) : undefined;

            for (var i = 0; i < positionsLength; ++i, startingIndex += Cartographic.Cartesian3.packedLength) {
                positions[i] = Cartographic.Cartesian3.unpack(array, startingIndex);
            }

            for (var j = 0; j < holesLength; ++j) {
                holes[j] = PolygonGeometryLibrary.unpackPolygonHierarchy(array, startingIndex);
                startingIndex = holes[j].startingIndex;
                delete holes[j].startingIndex;
            }

            return {
                positions : positions,
                holes : holes,
                startingIndex : startingIndex
            };
        };

        var distanceScratch = new Cartographic.Cartesian3();
        function getPointAtDistance(p0, p1, distance, length) {
            Cartographic.Cartesian3.subtract(p1, p0, distanceScratch);
            Cartographic.Cartesian3.multiplyByScalar(distanceScratch, distance / length, distanceScratch);
            Cartographic.Cartesian3.add(p0, distanceScratch, distanceScratch);
            return [distanceScratch.x, distanceScratch.y, distanceScratch.z];
        }

        PolygonGeometryLibrary.subdivideLineCount = function(p0, p1, minDistance) {
            var distance = Cartographic.Cartesian3.distance(p0, p1);
            var n = distance / minDistance;
            var countDivide = Math.max(0, Math.ceil(_Math.CesiumMath.log2(n)));
            return Math.pow(2, countDivide);
        };

        var scratchCartographic0 = new Cartographic.Cartographic();
        var scratchCartographic1 = new Cartographic.Cartographic();
        var scratchCartographic2 = new Cartographic.Cartographic();
        var scratchCartesian0 = new Cartographic.Cartesian3();
        PolygonGeometryLibrary.subdivideRhumbLineCount = function(ellipsoid, p0, p1, minDistance) {
            var c0 = ellipsoid.cartesianToCartographic(p0, scratchCartographic0);
            var c1 = ellipsoid.cartesianToCartographic(p1, scratchCartographic1);
            var rhumb = new EllipsoidRhumbLine.EllipsoidRhumbLine(c0, c1, ellipsoid);
            var n = rhumb.surfaceDistance / minDistance;
            var countDivide = Math.max(0, Math.ceil(_Math.CesiumMath.log2(n)));
            return Math.pow(2, countDivide);
        };

        PolygonGeometryLibrary.subdivideLine = function(p0, p1, minDistance, result) {
            var numVertices = PolygonGeometryLibrary.subdivideLineCount(p0, p1, minDistance);
            var length = Cartographic.Cartesian3.distance(p0, p1);
            var distanceBetweenVertices = length / numVertices;

            if (!when.defined(result)) {
                result = [];
            }

            var positions = result;
            positions.length = numVertices * 3;

            var index = 0;
            for ( var i = 0; i < numVertices; i++) {
                var p = getPointAtDistance(p0, p1, i * distanceBetweenVertices, length);
                positions[index++] = p[0];
                positions[index++] = p[1];
                positions[index++] = p[2];
            }

            return positions;
        };

        PolygonGeometryLibrary.subdivideRhumbLine = function(ellipsoid, p0, p1, minDistance, result) {
            var c0 = ellipsoid.cartesianToCartographic(p0, scratchCartographic0);
            var c1 = ellipsoid.cartesianToCartographic(p1, scratchCartographic1);
            var rhumb = new EllipsoidRhumbLine.EllipsoidRhumbLine(c0, c1, ellipsoid);

            var n = rhumb.surfaceDistance / minDistance;
            var countDivide = Math.max(0, Math.ceil(_Math.CesiumMath.log2(n)));
            var numVertices = Math.pow(2, countDivide);
            var distanceBetweenVertices = rhumb.surfaceDistance / numVertices;

            if (!when.defined(result)) {
                result = [];
            }

            var positions = result;
            positions.length = numVertices * 3;

            var index = 0;
            for ( var i = 0; i < numVertices; i++) {
                var c = rhumb.interpolateUsingSurfaceDistance(i * distanceBetweenVertices, scratchCartographic2);
                var p = ellipsoid.cartographicToCartesian(c, scratchCartesian0);
                positions[index++] = p.x;
                positions[index++] = p.y;
                positions[index++] = p.z;
            }

            return positions;
        };

        var scaleToGeodeticHeightN1 = new Cartographic.Cartesian3();
        var scaleToGeodeticHeightN2 = new Cartographic.Cartesian3();
        var scaleToGeodeticHeightP1 = new Cartographic.Cartesian3();
        var scaleToGeodeticHeightP2 = new Cartographic.Cartesian3();

        PolygonGeometryLibrary.scaleToGeodeticHeightExtruded = function(geometry, maxHeight, minHeight, ellipsoid, perPositionHeight) {
            ellipsoid = when.defaultValue(ellipsoid, Cartesian2.Ellipsoid.WGS84);

            var n1 = scaleToGeodeticHeightN1;
            var n2 = scaleToGeodeticHeightN2;
            var p = scaleToGeodeticHeightP1;
            var p2 = scaleToGeodeticHeightP2;

            if (when.defined(geometry) && when.defined(geometry.attributes) && when.defined(geometry.attributes.position)) {
                var positions = geometry.attributes.position.values;
                var length = positions.length / 2;

                for ( var i = 0; i < length; i += 3) {
                    Cartographic.Cartesian3.fromArray(positions, i, p);

                    ellipsoid.geodeticSurfaceNormal(p, n1);
                    p2 = ellipsoid.scaleToGeodeticSurface(p, p2);
                    n2 = Cartographic.Cartesian3.multiplyByScalar(n1, minHeight, n2);
                    n2 = Cartographic.Cartesian3.add(p2, n2, n2);
                    positions[i + length] = n2.x;
                    positions[i + 1 + length] = n2.y;
                    positions[i + 2 + length] = n2.z;

                    if (perPositionHeight) {
                        p2 = Cartographic.Cartesian3.clone(p, p2);
                    }
                    n2 = Cartographic.Cartesian3.multiplyByScalar(n1, maxHeight, n2);
                    n2 = Cartographic.Cartesian3.add(p2, n2, n2);
                    positions[i] = n2.x;
                    positions[i + 1] = n2.y;
                    positions[i + 2] = n2.z;
                }
            }
            return geometry;
        };

        PolygonGeometryLibrary.polygonOutlinesFromHierarchy = function(polygonHierarchy, scaleToEllipsoidSurface, ellipsoid) {
            // create from a polygon hierarchy
            // Algorithm adapted from http://www.geometrictools.com/Documentation/TriangulationByEarClipping.pdf
            var polygons = [];
            var queue = new Queue();
            queue.enqueue(polygonHierarchy);
            var i;
            var j;
            var length;
            while (queue.length !== 0) {
                var outerNode = queue.dequeue();
                var outerRing = outerNode.positions;
                if (scaleToEllipsoidSurface) {
                    length = outerRing.length;
                    for (i = 0; i < length; i++) {
                        ellipsoid.scaleToGeodeticSurface(outerRing[i], outerRing[i]);
                    }
                }
                outerRing = arrayRemoveDuplicates.arrayRemoveDuplicates(outerRing, Cartographic.Cartesian3.equalsEpsilon, true);
                if (outerRing.length < 3) {
                    continue;
                }

                var numChildren = outerNode.holes ? outerNode.holes.length : 0;
                // The outer polygon contains inner polygons
                for (i = 0; i < numChildren; i++) {
                    var hole = outerNode.holes[i];
                    var holePositions = hole.positions;
                    if (scaleToEllipsoidSurface) {
                        length = holePositions.length;
                        for (j = 0; j < length; ++j) {
                            ellipsoid.scaleToGeodeticSurface(holePositions[j], holePositions[j]);
                        }
                    }
                    holePositions = arrayRemoveDuplicates.arrayRemoveDuplicates(holePositions, Cartographic.Cartesian3.equalsEpsilon, true);
                    if (holePositions.length < 3) {
                        continue;
                    }
                    polygons.push(holePositions);

                    var numGrandchildren = 0;
                    if (when.defined(hole.holes)) {
                        numGrandchildren = hole.holes.length;
                    }

                    for (j = 0; j < numGrandchildren; j++) {
                        queue.enqueue(hole.holes[j]);
                    }
                }

                polygons.push(outerRing);
            }

            return polygons;
        };

        PolygonGeometryLibrary.polygonsFromHierarchy = function(polygonHierarchy, projectPointsTo2D, scaleToEllipsoidSurface, ellipsoid) {
            // create from a polygon hierarchy
            // Algorithm adapted from http://www.geometrictools.com/Documentation/TriangulationByEarClipping.pdf
            var hierarchy = [];
            var polygons = [];

            var queue = new Queue();
            queue.enqueue(polygonHierarchy);

            while (queue.length !== 0) {
                var outerNode = queue.dequeue();
                var outerRing = outerNode.positions;
                var holes = outerNode.holes;

                var i;
                var length;
                if (scaleToEllipsoidSurface) {
                    length = outerRing.length;
                    for (i = 0; i < length; i++) {
                        ellipsoid.scaleToGeodeticSurface(outerRing[i], outerRing[i]);
                    }
                }

                outerRing = arrayRemoveDuplicates.arrayRemoveDuplicates(outerRing, Cartographic.Cartesian3.equalsEpsilon, true);
                if (outerRing.length < 3) {
                    continue;
                }

                var positions2D = projectPointsTo2D(outerRing);
                if (!when.defined(positions2D)) {
                    continue;
                }
                var holeIndices = [];

                var originalWindingOrder = PolygonPipeline.PolygonPipeline.computeWindingOrder2D(positions2D);
                if (originalWindingOrder === PolygonPipeline.WindingOrder.CLOCKWISE) {
                    positions2D.reverse();
                    outerRing = outerRing.slice().reverse();
                }

                var positions = outerRing.slice();
                var numChildren = when.defined(holes) ? holes.length : 0;
                var polygonHoles = [];
                var j;

                for (i = 0; i < numChildren; i++) {
                    var hole = holes[i];
                    var holePositions = hole.positions;
                    if (scaleToEllipsoidSurface) {
                        length = holePositions.length;
                        for (j = 0; j < length; ++j) {
                            ellipsoid.scaleToGeodeticSurface(holePositions[j], holePositions[j]);
                        }
                    }

                    holePositions = arrayRemoveDuplicates.arrayRemoveDuplicates(holePositions, Cartographic.Cartesian3.equalsEpsilon, true);
                    if (holePositions.length < 3) {
                        continue;
                    }

                    var holePositions2D = projectPointsTo2D(holePositions);
                    if (!when.defined(holePositions2D)) {
                        continue;
                    }

                    originalWindingOrder = PolygonPipeline.PolygonPipeline.computeWindingOrder2D(holePositions2D);
                    if (originalWindingOrder === PolygonPipeline.WindingOrder.CLOCKWISE) {
                        holePositions2D.reverse();
                        holePositions = holePositions.slice().reverse();
                    }

                    polygonHoles.push(holePositions);
                    holeIndices.push(positions.length);
                    positions = positions.concat(holePositions);
                    positions2D = positions2D.concat(holePositions2D);

                    var numGrandchildren = 0;
                    if (when.defined(hole.holes)) {
                        numGrandchildren = hole.holes.length;
                    }

                    for (j = 0; j < numGrandchildren; j++) {
                        queue.enqueue(hole.holes[j]);
                    }
                }

                hierarchy.push({
                    outerRing : outerRing,
                    holes : polygonHoles
                });
                polygons.push({
                    positions : positions,
                    positions2D : positions2D,
                    holes : holeIndices
                });
            }

            return {
                hierarchy : hierarchy,
                polygons : polygons
            };
        };

        var computeBoundingRectangleCartesian2 = new Cartesian2.Cartesian2();
        var computeBoundingRectangleCartesian3 = new Cartographic.Cartesian3();
        var computeBoundingRectangleQuaternion = new Transforms.Quaternion();
        var computeBoundingRectangleMatrix3 = new BoundingSphere.Matrix3();
        PolygonGeometryLibrary.computeBoundingRectangle = function (planeNormal, projectPointTo2D, positions, angle, result) {
            var rotation = Transforms.Quaternion.fromAxisAngle(planeNormal, angle, computeBoundingRectangleQuaternion);
            var textureMatrix = BoundingSphere.Matrix3.fromQuaternion(rotation, computeBoundingRectangleMatrix3);

            var minX = Number.POSITIVE_INFINITY;
            var maxX = Number.NEGATIVE_INFINITY;
            var minY = Number.POSITIVE_INFINITY;
            var maxY = Number.NEGATIVE_INFINITY;

            var length = positions.length;
            for ( var i = 0; i < length; ++i) {
                var p = Cartographic.Cartesian3.clone(positions[i], computeBoundingRectangleCartesian3);
                BoundingSphere.Matrix3.multiplyByVector(textureMatrix, p, p);
                var st = projectPointTo2D(p, computeBoundingRectangleCartesian2);

                if (when.defined(st)) {
                    minX = Math.min(minX, st.x);
                    maxX = Math.max(maxX, st.x);

                    minY = Math.min(minY, st.y);
                    maxY = Math.max(maxY, st.y);
                }
            }

            result.x = minX;
            result.y = minY;
            result.width = maxX - minX;
            result.height = maxY - minY;
            return result;
        };

        PolygonGeometryLibrary.createGeometryFromPositions = function(ellipsoid, polygon, granularity, perPositionHeight, vertexFormat, arcType) {
            var indices = PolygonPipeline.PolygonPipeline.triangulate(polygon.positions2D, polygon.holes);

            /* If polygon is completely unrenderable, just use the first three vertices */
            if (indices.length < 3) {
                indices = [0, 1, 2];
            }

            var positions = polygon.positions;

            if (perPositionHeight) {
                var length = positions.length;
                var flattenedPositions = new Array(length * 3);
                var index = 0;
                for ( var i = 0; i < length; i++) {
                    var p = positions[i];
                    flattenedPositions[index++] = p.x;
                    flattenedPositions[index++] = p.y;
                    flattenedPositions[index++] = p.z;
                }
                var geometry = new GeometryAttribute.Geometry({
                    attributes : {
                        position : new GeometryAttribute.GeometryAttribute({
                            componentDatatype : ComponentDatatype.ComponentDatatype.DOUBLE,
                            componentsPerAttribute : 3,
                            values : flattenedPositions
                        })
                    },
                    indices : indices,
                    primitiveType : PrimitiveType.PrimitiveType.TRIANGLES
                });

                if (vertexFormat.normal) {
                    return GeometryPipeline.GeometryPipeline.computeNormal(geometry);
                }

                return geometry;
            }

            if (arcType === ArcType.ArcType.GEODESIC) {
                return PolygonPipeline.PolygonPipeline.computeSubdivision(ellipsoid, positions, indices, granularity);
            } else if (arcType === ArcType.ArcType.RHUMB) {
                return PolygonPipeline.PolygonPipeline.computeRhumbLineSubdivision(ellipsoid, positions, indices, granularity);
            }
        };

        var computeWallIndicesSubdivided = [];
        var p1Scratch = new Cartographic.Cartesian3();
        var p2Scratch = new Cartographic.Cartesian3();

        PolygonGeometryLibrary.computeWallGeometry = function(positions, ellipsoid, granularity, perPositionHeight, arcType) {
            var edgePositions;
            var topEdgeLength;
            var i;
            var p1;
            var p2;

            var length = positions.length;
            var index = 0;

            if (!perPositionHeight) {
                var minDistance = _Math.CesiumMath.chordLength(granularity, ellipsoid.maximumRadius);

                var numVertices = 0;
                if (arcType === ArcType.ArcType.GEODESIC) {
                    for (i = 0; i < length; i++) {
                        numVertices += PolygonGeometryLibrary.subdivideLineCount(positions[i], positions[(i + 1) % length], minDistance);
                    }
                } else if (arcType === ArcType.ArcType.RHUMB) {
                    for (i = 0; i < length; i++) {
                        numVertices += PolygonGeometryLibrary.subdivideRhumbLineCount(ellipsoid, positions[i], positions[(i + 1) % length], minDistance);
                    }
                }

                topEdgeLength = (numVertices + length) * 3;
                edgePositions = new Array(topEdgeLength * 2);
                for (i = 0; i < length; i++) {
                    p1 = positions[i];
                    p2 = positions[(i + 1) % length];

                    var tempPositions;
                    if (arcType === ArcType.ArcType.GEODESIC) {
                        tempPositions = PolygonGeometryLibrary.subdivideLine(p1, p2, minDistance, computeWallIndicesSubdivided);
                    } else if (arcType === ArcType.ArcType.RHUMB) {
                        tempPositions = PolygonGeometryLibrary.subdivideRhumbLine(ellipsoid, p1, p2, minDistance, computeWallIndicesSubdivided);
                    }
                    var tempPositionsLength = tempPositions.length;
                    for (var j = 0; j < tempPositionsLength; ++j, ++index) {
                        edgePositions[index] = tempPositions[j];
                        edgePositions[index + topEdgeLength] = tempPositions[j];
                    }

                    edgePositions[index] = p2.x;
                    edgePositions[index + topEdgeLength] = p2.x;
                    ++index;

                    edgePositions[index] = p2.y;
                    edgePositions[index + topEdgeLength] = p2.y;
                    ++index;

                    edgePositions[index] = p2.z;
                    edgePositions[index + topEdgeLength] = p2.z;
                    ++index;
                }
            } else {
                topEdgeLength = length * 3 * 2;
                edgePositions = new Array(topEdgeLength * 2);
                for (i = 0; i < length; i++) {
                    p1 = positions[i];
                    p2 = positions[(i + 1) % length];
                    edgePositions[index] = edgePositions[index + topEdgeLength] = p1.x;
                    ++index;
                    edgePositions[index] = edgePositions[index + topEdgeLength] = p1.y;
                    ++index;
                    edgePositions[index] = edgePositions[index + topEdgeLength] = p1.z;
                    ++index;
                    edgePositions[index] = edgePositions[index + topEdgeLength] = p2.x;
                    ++index;
                    edgePositions[index] = edgePositions[index + topEdgeLength] = p2.y;
                    ++index;
                    edgePositions[index] = edgePositions[index + topEdgeLength] = p2.z;
                    ++index;
                }
            }

            length = edgePositions.length;
            var indices = IndexDatatype.IndexDatatype.createTypedArray(length / 3, length - positions.length * 6);
            var edgeIndex = 0;
            length /= 6;

            for (i = 0; i < length; i++) {
                var UL = i;
                var UR = UL + 1;
                var LL = UL + length;
                var LR = LL + 1;

                p1 = Cartographic.Cartesian3.fromArray(edgePositions, UL * 3, p1Scratch);
                p2 = Cartographic.Cartesian3.fromArray(edgePositions, UR * 3, p2Scratch);
                if (Cartographic.Cartesian3.equalsEpsilon(p1, p2, _Math.CesiumMath.EPSILON14)) {
                    continue;
                }

                indices[edgeIndex++] = UL;
                indices[edgeIndex++] = LL;
                indices[edgeIndex++] = UR;
                indices[edgeIndex++] = UR;
                indices[edgeIndex++] = LL;
                indices[edgeIndex++] = LR;
            }

            return new GeometryAttribute.Geometry({
                attributes : new GeometryAttributes.GeometryAttributes({
                    position : new GeometryAttribute.GeometryAttribute({
                        componentDatatype : ComponentDatatype.ComponentDatatype.DOUBLE,
                        componentsPerAttribute : 3,
                        values : edgePositions
                    })
                }),
                indices : indices,
                primitiveType : PrimitiveType.PrimitiveType.TRIANGLES
            });
        };

    exports.PolygonGeometryLibrary = PolygonGeometryLibrary;

});