cesiumDemo/Source/Scene/GlobeSurfaceTile.js

import BoundingSphere from '../Core/BoundingSphere.js';
import Cartesian3 from '../Core/Cartesian3.js';
import Cartesian4 from '../Core/Cartesian4.js';
import defined from '../Core/defined.js';
import defineProperties from '../Core/defineProperties.js';
import IndexDatatype from '../Core/IndexDatatype.js';
import IntersectionTests from '../Core/IntersectionTests.js';
import OrientedBoundingBox from '../Core/OrientedBoundingBox.js';
import PixelFormat from '../Core/PixelFormat.js';
import Request from '../Core/Request.js';
import RequestState from '../Core/RequestState.js';
import RequestType from '../Core/RequestType.js';
import TileProviderError from '../Core/TileProviderError.js';
import Buffer from '../Renderer/Buffer.js';
import BufferUsage from '../Renderer/BufferUsage.js';
import PixelDatatype from '../Renderer/PixelDatatype.js';
import Sampler from '../Renderer/Sampler.js';
import Texture from '../Renderer/Texture.js';
import TextureMagnificationFilter from '../Renderer/TextureMagnificationFilter.js';
import TextureMinificationFilter from '../Renderer/TextureMinificationFilter.js';
import TextureWrap from '../Renderer/TextureWrap.js';
import VertexArray from '../Renderer/VertexArray.js';
import when from '../ThirdParty/when.js';
import ImageryState from './ImageryState.js';
import QuadtreeTileLoadState from './QuadtreeTileLoadState.js';
import SceneMode from './SceneMode.js';
import TerrainState from './TerrainState.js';

    /**
     * Contains additional information about a {@link QuadtreeTile} of the globe's surface, and
     * encapsulates state transition logic for loading tiles.
     *
     * @constructor
     * @alias GlobeSurfaceTile
     * @private
     */
    function GlobeSurfaceTile() {
        /**
         * The {@link TileImagery} attached to this tile.
         * @type {TileImagery[]}
         * @default []
         */
        this.imagery = [];

        this.waterMaskTexture = undefined;
        this.waterMaskTranslationAndScale = new Cartesian4(0.0, 0.0, 1.0, 1.0);

        this.terrainData = undefined;
        this.vertexArray = undefined;
        this.orientedBoundingBox = undefined;
        this.boundingVolumeSourceTile = undefined;

        /**
         * A bounding region used to estimate distance to the tile. The horizontal bounds are always tight-fitting,
         * but the `minimumHeight` and `maximumHeight` properties may be derived from the min/max of an ancestor tile
         * and be quite loose-fitting and thus very poor for estimating distance. The {@link TileBoundingRegion#boundingVolume}
         * and {@link TileBoundingRegion#boundingSphere} will always be undefined; tiles store these separately.
         * @type {TileBoundingRegion}
         */
        this.tileBoundingRegion = undefined;
        this.occludeePointInScaledSpace = new Cartesian3();

        this.terrainState = TerrainState.UNLOADED;
        this.mesh = undefined;
        this.fill = undefined;

        this.pickBoundingSphere = new BoundingSphere();

        this.surfaceShader = undefined;
        this.isClipped = true;

        this.clippedByBoundaries = false;
    }

    defineProperties(GlobeSurfaceTile.prototype, {
        /**
         * Gets a value indicating whether or not this tile is eligible to be unloaded.
         * Typically, a tile is ineligible to be unloaded while an asynchronous operation,
         * such as a request for data, is in progress on it.  A tile will never be
         * unloaded while it is needed for rendering, regardless of the value of this
         * property.
         * @memberof GlobeSurfaceTile.prototype
         * @type {Boolean}
         */
        eligibleForUnloading : {
            get : function() {
                // Do not remove tiles that are transitioning or that have
                // imagery that is transitioning.
                var terrainState = this.terrainState;
                var loadingIsTransitioning = terrainState === TerrainState.RECEIVING || terrainState === TerrainState.TRANSFORMING;

                var shouldRemoveTile = !loadingIsTransitioning;

                var imagery = this.imagery;
                for (var i = 0, len = imagery.length; shouldRemoveTile && i < len; ++i) {
                    var tileImagery = imagery[i];
                    shouldRemoveTile = !defined(tileImagery.loadingImagery) || tileImagery.loadingImagery.state !== ImageryState.TRANSITIONING;
                }

                return shouldRemoveTile;
            }
        },

        /**
         * Gets the {@link TerrainMesh} that is used for rendering this tile, if any.
         * Returns the value of the {@link GlobeSurfaceTile#mesh} property if
         * {@link GlobeSurfaceTile#vertexArray} is defined. Otherwise, It returns the
         * {@link TerrainFillMesh#mesh} property of the {@link GlobeSurfaceTile#fill}.
         * If there is no fill, it returns undefined.
         *
         * @memberof GlobeSurfaceTile.prototype
         * @type {TerrainMesh}
         */
        renderedMesh : {
            get : function() {
                if (defined(this.vertexArray)) {
                    return this.mesh;
                } else if (defined(this.fill)) {
                    return this.fill.mesh;
                }
                return undefined;
            }
        }
    });

    function getPosition(encoding, mode, projection, vertices, index, result) {
        encoding.decodePosition(vertices, index, result);

        if (defined(mode) && mode !== SceneMode.SCENE3D) {
            var ellipsoid = projection.ellipsoid;
            var positionCart = ellipsoid.cartesianToCartographic(result);
            projection.project(positionCart, result);
            Cartesian3.fromElements(result.z, result.x, result.y, result);
        }

        return result;
    }

    var scratchV0 = new Cartesian3();
    var scratchV1 = new Cartesian3();
    var scratchV2 = new Cartesian3();
    var scratchResult = new Cartesian3();

    GlobeSurfaceTile.prototype.pick = function(ray, mode, projection, cullBackFaces, result) {
        var mesh = this.renderedMesh;
        if (!defined(mesh)) {
            return undefined;
        }

        var vertices = mesh.vertices;
        var indices = mesh.indices;
        var encoding = mesh.encoding;

        var length = indices.length;
        for (var i = 0; i < length; i += 3) {
            var i0 = indices[i];
            var i1 = indices[i + 1];
            var i2 = indices[i + 2];

            var v0 = getPosition(encoding, mode, projection, vertices, i0, scratchV0);
            var v1 = getPosition(encoding, mode, projection, vertices, i1, scratchV1);
            var v2 = getPosition(encoding, mode, projection, vertices, i2, scratchV2);

            var intersection = IntersectionTests.rayTriangle(ray, v0, v1, v2, cullBackFaces, scratchResult);
            if (defined(intersection)) {
                return Cartesian3.clone(intersection, result);
            }
        }

        return undefined;
    };

    GlobeSurfaceTile.prototype.freeResources = function() {
        if (defined(this.waterMaskTexture)) {
            --this.waterMaskTexture.referenceCount;
            if (this.waterMaskTexture.referenceCount === 0) {
                this.waterMaskTexture.destroy();
            }
            this.waterMaskTexture = undefined;
        }

        this.terrainData = undefined;

        this.terrainState = TerrainState.UNLOADED;
        this.mesh = undefined;
        this.fill = this.fill && this.fill.destroy();

        var imageryList = this.imagery;
        for (var i = 0, len = imageryList.length; i < len; ++i) {
            imageryList[i].freeResources();
        }
        this.imagery.length = 0;

        this.freeVertexArray();
    };

    GlobeSurfaceTile.prototype.freeVertexArray = function() {
        GlobeSurfaceTile._freeVertexArray(this.vertexArray);
        this.vertexArray = undefined;
        GlobeSurfaceTile._freeVertexArray(this.wireframeVertexArray);
        this.wireframeVertexArray = undefined;
    };

    GlobeSurfaceTile.initialize = function(tile, terrainProvider, imageryLayerCollection) {
        var surfaceTile = tile.data;
        if (!defined(surfaceTile)) {
            surfaceTile = tile.data = new GlobeSurfaceTile();
        }

        if (tile.state === QuadtreeTileLoadState.START) {
            prepareNewTile(tile, terrainProvider, imageryLayerCollection);
            tile.state = QuadtreeTileLoadState.LOADING;
        }
    };

    GlobeSurfaceTile.processStateMachine = function(tile, frameState, terrainProvider, imageryLayerCollection, vertexArraysToDestroy, terrainOnly) {
        GlobeSurfaceTile.initialize(tile, terrainProvider, imageryLayerCollection);

        var surfaceTile = tile.data;

        if (tile.state === QuadtreeTileLoadState.LOADING) {
            processTerrainStateMachine(tile, frameState, terrainProvider, imageryLayerCollection, vertexArraysToDestroy);
        }

        // From here down we're loading imagery, not terrain. We don't want to load imagery until
        // we're certain that the terrain tiles are actually visible, though. We'll load terrainOnly
        // in these scenarios:
        //   * our bounding volume isn't accurate so we're not certain this tile is really visible (see GlobeSurfaceTileProvider#loadTile).
        //   * we want to upsample from this tile but don't plan to render it (see processTerrainStateMachine).
        if (terrainOnly) {
            return;
        }

        var wasAlreadyRenderable = tile.renderable;

        // The terrain is renderable as soon as we have a valid vertex array.
        tile.renderable = defined(surfaceTile.vertexArray);

        // But it's not done loading until it's in the READY state.
        var isTerrainDoneLoading = surfaceTile.terrainState === TerrainState.READY;

        // If this tile's terrain and imagery are just upsampled from its parent, mark the tile as
        // upsampled only.  We won't refine a tile if its four children are upsampled only.
        tile.upsampledFromParent = defined(surfaceTile.terrainData) && surfaceTile.terrainData.wasCreatedByUpsampling();

        var isImageryDoneLoading = surfaceTile.processImagery(tile, terrainProvider, frameState);

        if (isTerrainDoneLoading && isImageryDoneLoading) {
            var callbacks = tile._loadedCallbacks;
            var newCallbacks = {};
            for(var layerId in callbacks) {
                if (callbacks.hasOwnProperty(layerId)) {
                    if(!callbacks[layerId](tile)) {
                        newCallbacks[layerId] = callbacks[layerId];
                    }
                }
            }
            tile._loadedCallbacks = newCallbacks;

            tile.state = QuadtreeTileLoadState.DONE;
        }

        // Once a tile is renderable, it stays renderable, because doing otherwise would
        // cause detail (or maybe even the entire globe) to vanish when adding a new
        // imagery layer. `GlobeSurfaceTileProvider._onLayerAdded` sets renderable to
        // false for all affected tiles that are not currently being rendered.
        if (wasAlreadyRenderable) {
            tile.renderable = true;
        }
    };

    GlobeSurfaceTile.prototype.processImagery = function(tile, terrainProvider, frameState, skipLoading) {
        var surfaceTile = tile.data;
        var isUpsampledOnly = tile.upsampledFromParent;
        var isAnyTileLoaded = false;
        var isDoneLoading = true;

        // Transition imagery states
        var tileImageryCollection = surfaceTile.imagery;
        var i, len;
        for (i = 0, len = tileImageryCollection.length; i < len; ++i) {
            var tileImagery = tileImageryCollection[i];
            if (!defined(tileImagery.loadingImagery)) {
                isUpsampledOnly = false;
                continue;
            }

            if (tileImagery.loadingImagery.state === ImageryState.PLACEHOLDER) {
                var imageryLayer = tileImagery.loadingImagery.imageryLayer;
                if (imageryLayer.imageryProvider.ready) {
                    // Remove the placeholder and add the actual skeletons (if any)
                    // at the same position.  Then continue the loop at the same index.
                    tileImagery.freeResources();
                    tileImageryCollection.splice(i, 1);
                    imageryLayer._createTileImagerySkeletons(tile, terrainProvider, i);
                    --i;
                    len = tileImageryCollection.length;
                    continue;
                } else {
                    isUpsampledOnly = false;
                }
            }

            var thisTileDoneLoading = tileImagery.processStateMachine(tile, frameState, skipLoading);
            isDoneLoading = isDoneLoading && thisTileDoneLoading;

            // The imagery is renderable as soon as we have any renderable imagery for this region.
            isAnyTileLoaded = isAnyTileLoaded || (thisTileDoneLoading || defined(tileImagery.readyImagery));

            isUpsampledOnly = isUpsampledOnly && defined(tileImagery.loadingImagery) &&
                              (tileImagery.loadingImagery.state === ImageryState.FAILED || tileImagery.loadingImagery.state === ImageryState.INVALID);
        }

        tile.upsampledFromParent = isUpsampledOnly;

        // Allow rendering if any available layers are loaded
        tile.renderable = tile.renderable && (isAnyTileLoaded || isDoneLoading);

        return isDoneLoading;
    };

    function prepareNewTile(tile, terrainProvider, imageryLayerCollection) {
        var available = terrainProvider.getTileDataAvailable(tile.x, tile.y, tile.level);

        if (!defined(available) && defined(tile.parent)) {
            // Provider doesn't know if this tile is available. Does the parent tile know?
            var parent = tile.parent;
            var parentSurfaceTile = parent.data;
            if (defined(parentSurfaceTile) && defined(parentSurfaceTile.terrainData)) {
                available = parentSurfaceTile.terrainData.isChildAvailable(parent.x, parent.y, tile.x, tile.y);
            }
        }

        if (available === false) {
            // This tile is not available, so mark it failed so we start upsampling right away.
            tile.data.terrainState = TerrainState.FAILED;
        }

        // Map imagery tiles to this terrain tile
        for (var i = 0, len = imageryLayerCollection.length; i < len; ++i) {
            var layer = imageryLayerCollection.get(i);
            if (layer.show) {
                layer._createTileImagerySkeletons(tile, terrainProvider);
            }
        }
    }

    function processTerrainStateMachine(tile, frameState, terrainProvider, imageryLayerCollection, vertexArraysToDestroy) {
        var surfaceTile = tile.data;

        // If this tile is FAILED, we'll need to upsample from the parent. If the parent isn't
        // ready for that, let's push it along.
        var parent = tile.parent;
        if (surfaceTile.terrainState === TerrainState.FAILED && parent !== undefined) {
            var parentReady = parent.data !== undefined && parent.data.terrainData !== undefined && parent.data.terrainData.canUpsample !== false;
            if (!parentReady) {
                GlobeSurfaceTile.processStateMachine(parent, frameState, terrainProvider, imageryLayerCollection, true);
            }
        }

        if (surfaceTile.terrainState === TerrainState.FAILED) {
            upsample(surfaceTile, tile, frameState, terrainProvider, tile.x, tile.y, tile.level);
        }

        if (surfaceTile.terrainState === TerrainState.UNLOADED) {
            requestTileGeometry(surfaceTile, terrainProvider, tile.x, tile.y, tile.level);
        }

        if (surfaceTile.terrainState === TerrainState.RECEIVED) {
            transform(surfaceTile, frameState, terrainProvider, tile.x, tile.y, tile.level);
        }

        if (surfaceTile.terrainState === TerrainState.TRANSFORMED) {
            createResources(surfaceTile, frameState.context, terrainProvider, tile.x, tile.y, tile.level, vertexArraysToDestroy);
        }

        if (surfaceTile.terrainState >= TerrainState.RECEIVED && surfaceTile.waterMaskTexture === undefined && terrainProvider.hasWaterMask) {
            var terrainData = surfaceTile.terrainData;
            if (terrainData.waterMask !== undefined) {
                createWaterMaskTextureIfNeeded(frameState.context, surfaceTile);
            } else {
                var sourceTile = surfaceTile._findAncestorTileWithTerrainData(tile);
                if (defined(sourceTile) && defined(sourceTile.data.waterMaskTexture)) {
                    surfaceTile.waterMaskTexture = sourceTile.data.waterMaskTexture;
                    ++surfaceTile.waterMaskTexture.referenceCount;
                    surfaceTile._computeWaterMaskTranslationAndScale(tile, sourceTile, surfaceTile.waterMaskTranslationAndScale);
                }
            }
        }
    }

    function upsample(surfaceTile, tile, frameState, terrainProvider, x, y, level) {
        var parent = tile.parent;
        if (!parent) {
            // Trying to upsample from a root tile. No can do. This tile is a failure.
            tile.state = QuadtreeTileLoadState.FAILED;
            return;
        }

        var sourceData = parent.data.terrainData;
        var sourceX = parent.x;
        var sourceY = parent.y;
        var sourceLevel = parent.level;

        if (!defined(sourceData)) {
            // Parent is not available, so we can't upsample this tile yet.
            return;
        }

        var terrainDataPromise = sourceData.upsample(terrainProvider.tilingScheme, sourceX, sourceY, sourceLevel, x, y, level);
        if (!defined(terrainDataPromise)) {
            // The upsample request has been deferred - try again later.
            return;
        }

        surfaceTile.terrainState = TerrainState.RECEIVING;

        when(terrainDataPromise, function(terrainData) {
            surfaceTile.terrainData = terrainData;
            surfaceTile.terrainState = TerrainState.RECEIVED;
        }, function() {
            surfaceTile.terrainState = TerrainState.FAILED;
        });
    }

    function requestTileGeometry(surfaceTile, terrainProvider, x, y, level) {
        function success(terrainData) {
            surfaceTile.terrainData = terrainData;
            surfaceTile.terrainState = TerrainState.RECEIVED;
            surfaceTile.request = undefined;
        }

        function failure() {
            if (surfaceTile.request.state === RequestState.CANCELLED) {
                // Cancelled due to low priority - try again later.
                surfaceTile.terrainData = undefined;
                surfaceTile.terrainState = TerrainState.UNLOADED;
                surfaceTile.request = undefined;
                return;
            }

            // Initially assume failure.  handleError may retry, in which case the state will
            // change to RECEIVING or UNLOADED.
            surfaceTile.terrainState = TerrainState.FAILED;
            surfaceTile.request = undefined;

            var message = 'Failed to obtain terrain tile X: ' + x + ' Y: ' + y + ' Level: ' + level + '.';
            terrainProvider._requestError = TileProviderError.handleError(
                terrainProvider._requestError,
                terrainProvider,
                terrainProvider.errorEvent,
                message,
                x, y, level,
                doRequest);
        }

        function doRequest() {
            // Request the terrain from the terrain provider.
            var request = new Request({
                throttle : false,
                throttleByServer : true,
                type : RequestType.TERRAIN
            });
            surfaceTile.request = request;
            var requestPromise = terrainProvider.requestTileGeometry(x, y, level, request);

            // If the request method returns undefined (instead of a promise), the request
            // has been deferred.
            if (defined(requestPromise)) {
                surfaceTile.terrainState = TerrainState.RECEIVING;
                when(requestPromise, success, failure);
            } else {
                // Deferred - try again later.
                surfaceTile.terrainState = TerrainState.UNLOADED;
                surfaceTile.request = undefined;
            }
        }

        doRequest();
    }

    function transform(surfaceTile, frameState, terrainProvider, x, y, level) {
        var tilingScheme = terrainProvider.tilingScheme;

        var terrainData = surfaceTile.terrainData;
        var meshPromise = terrainData.createMesh(tilingScheme, x, y, level, frameState.terrainExaggeration);

        if (!defined(meshPromise)) {
            // Postponed.
            return;
        }

        surfaceTile.terrainState = TerrainState.TRANSFORMING;

        when(meshPromise, function(mesh) {
            surfaceTile.mesh = mesh;
            surfaceTile.orientedBoundingBox = OrientedBoundingBox.clone(mesh.orientedBoundingBox, surfaceTile.orientedBoundingBox);
            surfaceTile.occludeePointInScaledSpace = Cartesian3.clone(mesh.occludeePointInScaledSpace, surfaceTile.occludeePointInScaledSpace);
            surfaceTile.terrainState = TerrainState.TRANSFORMED;
        }, function() {
            surfaceTile.terrainState = TerrainState.FAILED;
        });
    }

    GlobeSurfaceTile._createVertexArrayForMesh = function(context, mesh) {
        var typedArray = mesh.vertices;
        var buffer = Buffer.createVertexBuffer({
            context : context,
            typedArray : typedArray,
            usage : BufferUsage.STATIC_DRAW
        });
        var attributes = mesh.encoding.getAttributes(buffer);

        var indexBuffers = mesh.indices.indexBuffers || {};
        var indexBuffer = indexBuffers[context.id];
        if (!defined(indexBuffer) || indexBuffer.isDestroyed()) {
            var indices = mesh.indices;
            indexBuffer = Buffer.createIndexBuffer({
                context : context,
                typedArray : indices,
                usage : BufferUsage.STATIC_DRAW,
                indexDatatype : IndexDatatype.fromSizeInBytes(indices.BYTES_PER_ELEMENT)
            });
            indexBuffer.vertexArrayDestroyable = false;
            indexBuffer.referenceCount = 1;
            indexBuffers[context.id] = indexBuffer;
            mesh.indices.indexBuffers = indexBuffers;
        } else {
            ++indexBuffer.referenceCount;
        }

        return new VertexArray({
            context : context,
            attributes : attributes,
            indexBuffer : indexBuffer
        });
    };

    GlobeSurfaceTile._freeVertexArray = function(vertexArray) {
        if (defined(vertexArray)) {
            var indexBuffer = vertexArray.indexBuffer;

            vertexArray.destroy();

            if (defined(indexBuffer) && !indexBuffer.isDestroyed() && defined(indexBuffer.referenceCount)) {
                --indexBuffer.referenceCount;
                if (indexBuffer.referenceCount === 0) {
                    indexBuffer.destroy();
                }
            }
        }

    };

    function createResources(surfaceTile, context, terrainProvider, x, y, level, vertexArraysToDestroy) {
        surfaceTile.vertexArray = GlobeSurfaceTile._createVertexArrayForMesh(context, surfaceTile.mesh);
        surfaceTile.terrainState = TerrainState.READY;
        surfaceTile.fill = surfaceTile.fill && surfaceTile.fill.destroy(vertexArraysToDestroy);
    }

    function getContextWaterMaskData(context) {
        var data = context.cache.tile_waterMaskData;

        if (!defined(data)) {
            var allWaterTexture = Texture.create({
                context : context,
                pixelFormat : PixelFormat.LUMINANCE,
                pixelDatatype : PixelDatatype.UNSIGNED_BYTE,
                source : {
                    arrayBufferView : new Uint8Array([255]),
                    width : 1,
                    height : 1
                }
            });
            allWaterTexture.referenceCount = 1;

            var sampler = new Sampler({
                wrapS : TextureWrap.CLAMP_TO_EDGE,
                wrapT : TextureWrap.CLAMP_TO_EDGE,
                minificationFilter : TextureMinificationFilter.LINEAR,
                magnificationFilter : TextureMagnificationFilter.LINEAR
            });

            data = {
                allWaterTexture : allWaterTexture,
                sampler : sampler,
                destroy : function() {
                    this.allWaterTexture.destroy();
                }
            };

            context.cache.tile_waterMaskData = data;
        }

        return data;
    }

    function createWaterMaskTextureIfNeeded(context, surfaceTile) {
        var waterMask = surfaceTile.terrainData.waterMask;
        var waterMaskData = getContextWaterMaskData(context);
        var texture;

        var waterMaskLength = waterMask.length;
        if (waterMaskLength === 1) {
            // Length 1 means the tile is entirely land or entirely water.
            // A value of 0 indicates entirely land, a value of 1 indicates entirely water.
            if (waterMask[0] !== 0) {
                texture = waterMaskData.allWaterTexture;
            } else {
                // Leave the texture undefined if the tile is entirely land.
                return;
            }
        } else {
            var textureSize = Math.sqrt(waterMaskLength);
            texture = Texture.create({
                context : context,
                pixelFormat : PixelFormat.LUMINANCE,
                pixelDatatype : PixelDatatype.UNSIGNED_BYTE,
                source : {
                    width : textureSize,
                    height : textureSize,
                    arrayBufferView : waterMask
                },
                sampler : waterMaskData.sampler,
                flipY : false
            });

            texture.referenceCount = 0;
        }

        ++texture.referenceCount;
        surfaceTile.waterMaskTexture = texture;

        Cartesian4.fromElements(0.0, 0.0, 1.0, 1.0, surfaceTile.waterMaskTranslationAndScale);
    }

    GlobeSurfaceTile.prototype._findAncestorTileWithTerrainData = function(tile) {
        var sourceTile = tile.parent;

        while (defined(sourceTile) && (!defined(sourceTile.data) || !defined(sourceTile.data.terrainData) || sourceTile.data.terrainData.wasCreatedByUpsampling())) {
            sourceTile = sourceTile.parent;
        }

        return sourceTile;
    };

    GlobeSurfaceTile.prototype._computeWaterMaskTranslationAndScale = function(tile, sourceTile, result) {
        var sourceTileRectangle = sourceTile.rectangle;
        var tileRectangle = tile.rectangle;
        var tileWidth = tileRectangle.width;
        var tileHeight = tileRectangle.height;

        var scaleX = tileWidth / sourceTileRectangle.width;
        var scaleY = tileHeight / sourceTileRectangle.height;
        result.x = scaleX * (tileRectangle.west - sourceTileRectangle.west) / tileWidth;
        result.y = scaleY * (tileRectangle.south - sourceTileRectangle.south) / tileHeight;
        result.z = scaleX;
        result.w = scaleY;

        return result;
    };
export default GlobeSurfaceTile;