/*global define*/
define([
'../Core/BoundingRectangle',
'../Core/Cartesian2',
'../Core/Cartesian4',
'../Core/Color',
'../Core/ComponentDatatype',
'../Core/defaultValue',
'../Core/defined',
'../Core/defineProperties',
'../Core/destroyObject',
'../Core/FeatureDetection',
'../Core/GeographicTilingScheme',
'../Core/IndexDatatype',
'../Core/Math',
'../Core/PixelFormat',
'../Core/PrimitiveType',
'../Core/Rectangle',
'../Core/TerrainProvider',
'../Core/TileProviderError',
'../Renderer/BufferUsage',
'../Renderer/ClearCommand',
'../Renderer/DrawCommand',
'../Renderer/MipmapHint',
'../Renderer/ShaderSource',
'../Renderer/TextureMagnificationFilter',
'../Renderer/TextureMinificationFilter',
'../Renderer/TextureWrap',
'../Shaders/ReprojectWebMercatorFS',
'../Shaders/ReprojectWebMercatorVS',
'../ThirdParty/when',
'./Imagery',
'./ImageryState',
'./TileImagery'
], function(
BoundingRectangle,
Cartesian2,
Cartesian4,
Color,
ComponentDatatype,
defaultValue,
defined,
defineProperties,
destroyObject,
FeatureDetection,
GeographicTilingScheme,
IndexDatatype,
CesiumMath,
PixelFormat,
PrimitiveType,
Rectangle,
TerrainProvider,
TileProviderError,
BufferUsage,
ClearCommand,
DrawCommand,
MipmapHint,
ShaderSource,
TextureMagnificationFilter,
TextureMinificationFilter,
TextureWrap,
ReprojectWebMercatorFS,
ReprojectWebMercatorVS,
when,
Imagery,
ImageryState,
TileImagery) {
"use strict";
/**
* An imagery layer that displays tiled image data from a single imagery provider
* on a {@link Globe}.
*
* @alias ImageryLayer
* @constructor
*
* @param {ImageryProvider} imageryProvider The imagery provider to use.
* @param {Object} [options] Object with the following properties:
* @param {Rectangle} [options.rectangle=imageryProvider.rectangle] The rectangle of the layer. This rectangle
* can limit the visible portion of the imagery provider.
* @param {Number|Function} [options.alpha=1.0] The alpha blending value of this layer, from 0.0 to 1.0.
* This can either be a simple number or a function with the signature
* <code>function(frameState, layer, x, y, level)</code>. The function is passed the
* current frame state, this layer, and the x, y, and level coordinates of the
* imagery tile for which the alpha is required, and it is expected to return
* the alpha value to use for the tile.
* @param {Number|Function} [options.brightness=1.0] The brightness of this layer. 1.0 uses the unmodified imagery
* color. Less than 1.0 makes the imagery darker while greater than 1.0 makes it brighter.
* This can either be a simple number or a function with the signature
* <code>function(frameState, layer, x, y, level)</code>. The function is passed the
* current frame state, this layer, and the x, y, and level coordinates of the
* imagery tile for which the brightness is required, and it is expected to return
* the brightness value to use for the tile. The function is executed for every
* frame and for every tile, so it must be fast.
* @param {Number|Function} [options.contrast=1.0] The contrast of this layer. 1.0 uses the unmodified imagery color.
* Less than 1.0 reduces the contrast while greater than 1.0 increases it.
* This can either be a simple number or a function with the signature
* <code>function(frameState, layer, x, y, level)</code>. The function is passed the
* current frame state, this layer, and the x, y, and level coordinates of the
* imagery tile for which the contrast is required, and it is expected to return
* the contrast value to use for the tile. The function is executed for every
* frame and for every tile, so it must be fast.
* @param {Number|Function} [options.hue=0.0] The hue of this layer. 0.0 uses the unmodified imagery color.
* This can either be a simple number or a function with the signature
* <code>function(frameState, layer, x, y, level)</code>. The function is passed the
* current frame state, this layer, and the x, y, and level coordinates
* of the imagery tile for which the hue is required, and it is expected to return
* the contrast value to use for the tile. The function is executed for every
* frame and for every tile, so it must be fast.
* @param {Number|Function} [options.saturation=1.0] The saturation of this layer. 1.0 uses the unmodified imagery color.
* Less than 1.0 reduces the saturation while greater than 1.0 increases it.
* This can either be a simple number or a function with the signature
* <code>function(frameState, layer, x, y, level)</code>. The function is passed the
* current frame state, this layer, and the x, y, and level coordinates
* of the imagery tile for which the saturation is required, and it is expected to return
* the contrast value to use for the tile. The function is executed for every
* frame and for every tile, so it must be fast.
* @param {Number|Function} [options.gamma=1.0] The gamma correction to apply to this layer. 1.0 uses the unmodified imagery color.
* This can either be a simple number or a function with the signature
* <code>function(frameState, layer, x, y, level)</code>. The function is passed the
* current frame state, this layer, and the x, y, and level coordinates of the
* imagery tile for which the gamma is required, and it is expected to return
* the gamma value to use for the tile. The function is executed for every
* frame and for every tile, so it must be fast.
* @param {Boolean} [options.show=true] True if the layer is shown; otherwise, false.
* @param {Number} [options.maximumAnisotropy=maximum supported] The maximum anisotropy level to use
* for texture filtering. If this parameter is not specified, the maximum anisotropy supported
* by the WebGL stack will be used. Larger values make the imagery look better in horizon
* views.
* @param {Number} [options.minimumTerrainLevel] The minimum terrain level-of-detail at which to show this imagery layer,
* or undefined to show it at all levels. Level zero is the least-detailed level.
* @param {Number} [options.maximumTerrainLevel] The maximum terrain level-of-detail at which to show this imagery layer,
* or undefined to show it at all levels. Level zero is the least-detailed level.
*/
var ImageryLayer = function ImageryLayer(imageryProvider, options) {
this._imageryProvider = imageryProvider;
options = defaultValue(options, {});
/**
* The alpha blending value of this layer, with 0.0 representing fully transparent and
* 1.0 representing fully opaque.
*
* @type {Number}
* @default 1.0
*/
this.alpha = defaultValue(options.alpha, defaultValue(imageryProvider.defaultAlpha, 1.0));
/**
* The brightness of this layer. 1.0 uses the unmodified imagery color. Less than 1.0
* makes the imagery darker while greater than 1.0 makes it brighter.
*
* @type {Number}
* @default {@link ImageryLayer.DEFAULT_BRIGHTNESS}
*/
this.brightness = defaultValue(options.brightness, defaultValue(imageryProvider.defaultBrightness, ImageryLayer.DEFAULT_BRIGHTNESS));
/**
* The contrast of this layer. 1.0 uses the unmodified imagery color. Less than 1.0 reduces
* the contrast while greater than 1.0 increases it.
*
* @type {Number}
* @default {@link ImageryLayer.DEFAULT_CONTRAST}
*/
this.contrast = defaultValue(options.contrast, defaultValue(imageryProvider.defaultContrast, ImageryLayer.DEFAULT_CONTRAST));
/**
* The hue of this layer in radians. 0.0 uses the unmodified imagery color.
*
* @type {Number}
* @default {@link ImageryLayer.DEFAULT_HUE}
*/
this.hue = defaultValue(options.hue, defaultValue(imageryProvider.defaultHue, ImageryLayer.DEFAULT_HUE));
/**
* The saturation of this layer. 1.0 uses the unmodified imagery color. Less than 1.0 reduces the
* saturation while greater than 1.0 increases it.
*
* @type {Number}
* @default {@link ImageryLayer.DEFAULT_SATURATION}
*/
this.saturation = defaultValue(options.saturation, defaultValue(imageryProvider.defaultSaturation, ImageryLayer.DEFAULT_SATURATION));
/**
* The gamma correction to apply to this layer. 1.0 uses the unmodified imagery color.
*
* @type {Number}
* @default {@link ImageryLayer.DEFAULT_GAMMA}
*/
this.gamma = defaultValue(options.gamma, defaultValue(imageryProvider.defaultGamma, ImageryLayer.DEFAULT_GAMMA));
/**
* Determines if this layer is shown.
*
* @type {Boolean}
* @default true
*/
this.show = defaultValue(options.show, true);
this._minimumTerrainLevel = options.minimumTerrainLevel;
this._maximumTerrainLevel = options.maximumTerrainLevel;
this._rectangle = defaultValue(options.rectangle, Rectangle.MAX_VALUE);
this._maximumAnisotropy = options.maximumAnisotropy;
this._imageryCache = {};
this._skeletonPlaceholder = new TileImagery(Imagery.createPlaceholder(this));
// The value of the show property on the last update.
this._show = true;
// The index of this layer in the ImageryLayerCollection.
this._layerIndex = -1;
// true if this is the base (lowest shown) layer.
this._isBaseLayer = false;
this._requestImageError = undefined;
};
defineProperties(ImageryLayer.prototype, {
/**
* Gets the imagery provider for this layer.
* @memberof ImageryLayer.prototype
* @type {ImageryProvider}
* @readonly
*/
imageryProvider : {
get: function() {
return this._imageryProvider;
}
},
/**
* Gets the rectangle of this layer. If this rectangle is smaller than the rectangle of the
* {@link ImageryProvider}, only a portion of the imagery provider is shown.
* @memberof ImageryLayer.prototype
* @type {Rectangle}
* @readonly
*/
rectangle: {
get: function() {
return this._rectangle;
}
}
});
/**
* This value is used as the default brightness for the imagery layer if one is not provided during construction
* or by the imagery provider. This value does not modify the brightness of the imagery.
* @type {Number}
* @default 1.0
*/
ImageryLayer.DEFAULT_BRIGHTNESS = 1.0;
/**
* This value is used as the default contrast for the imagery layer if one is not provided during construction
* or by the imagery provider. This value does not modify the contrast of the imagery.
* @type {Number}
* @default 1.0
*/
ImageryLayer.DEFAULT_CONTRAST = 1.0;
/**
* This value is used as the default hue for the imagery layer if one is not provided during construction
* or by the imagery provider. This value does not modify the hue of the imagery.
* @type {Number}
* @default 0.0
*/
ImageryLayer.DEFAULT_HUE = 0.0;
/**
* This value is used as the default saturation for the imagery layer if one is not provided during construction
* or by the imagery provider. This value does not modify the saturation of the imagery.
* @type {Number}
* @default 1.0
*/
ImageryLayer.DEFAULT_SATURATION = 1.0;
/**
* This value is used as the default gamma for the imagery layer if one is not provided during construction
* or by the imagery provider. This value does not modify the gamma of the imagery.
* @type {Number}
* @default 1.0
*/
ImageryLayer.DEFAULT_GAMMA = 1.0;
/**
* Gets a value indicating whether this layer is the base layer in the
* {@link ImageryLayerCollection}. The base layer is the one that underlies all
* others. It is special in that it is treated as if it has global rectangle, even if
* it actually does not, by stretching the texels at the edges over the entire
* globe.
*
* @returns {Boolean} true if this is the base layer; otherwise, false.
*/
ImageryLayer.prototype.isBaseLayer = function() {
return this._isBaseLayer;
};
/**
* Returns true if this object was destroyed; otherwise, false.
* <br /><br />
* If this object was destroyed, it should not be used; calling any function other than
* <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
*
* @returns {Boolean} True if this object was destroyed; otherwise, false.
*
* @see ImageryLayer#destroy
*/
ImageryLayer.prototype.isDestroyed = function() {
return false;
};
/**
* Destroys the WebGL resources held by this object. Destroying an object allows for deterministic
* release of WebGL resources, instead of relying on the garbage collector to destroy this object.
* <br /><br />
* Once an object is destroyed, it should not be used; calling any function other than
* <code>isDestroyed</code> will result in a {@link DeveloperError} exception. Therefore,
* assign the return value (<code>undefined</code>) to the object as done in the example.
*
* @returns {undefined}
*
* @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
*
* @see ImageryLayer#isDestroyed
*
* @example
* imageryLayer = imageryLayer && imageryLayer.destroy();
*/
ImageryLayer.prototype.destroy = function() {
return destroyObject(this);
};
var imageryBoundsScratch = new Rectangle();
var tileImageryBoundsScratch = new Rectangle();
var clippedRectangleScratch = new Rectangle();
/**
* Create skeletons for the imagery tiles that partially or completely overlap a given terrain
* tile.
*
* @private
*
* @param {Tile} tile The terrain tile.
* @param {TerrainProvider} terrainProvider The terrain provider associated with the terrain tile.
* @param {Number} insertionPoint The position to insert new skeletons before in the tile's imagery lsit.
* @returns {Boolean} true if this layer overlaps any portion of the terrain tile; otherwise, false.
*/
ImageryLayer.prototype._createTileImagerySkeletons = function(tile, terrainProvider, insertionPoint) {
var surfaceTile = tile.data;
if (defined(this._minimumTerrainLevel) && tile.level < this._minimumTerrainLevel) {
return false;
}
if (defined(this._maximumTerrainLevel) && tile.level > this._maximumTerrainLevel) {
return false;
}
var imageryProvider = this._imageryProvider;
if (!defined(insertionPoint)) {
insertionPoint = surfaceTile.imagery.length;
}
if (!imageryProvider.ready) {
// The imagery provider is not ready, so we can't create skeletons, yet.
// Instead, add a placeholder so that we'll know to create
// the skeletons once the provider is ready.
this._skeletonPlaceholder.loadingImagery.addReference();
surfaceTile.imagery.splice(insertionPoint, 0, this._skeletonPlaceholder);
return true;
}
// Compute the rectangle of the imagery from this imageryProvider that overlaps
// the geometry tile. The ImageryProvider and ImageryLayer both have the
// opportunity to constrain the rectangle. The imagery TilingScheme's rectangle
// always fully contains the ImageryProvider's rectangle.
var imageryBounds = Rectangle.intersection(imageryProvider.rectangle, this._rectangle, imageryBoundsScratch);
var rectangle = Rectangle.intersection(tile.rectangle, imageryBounds, tileImageryBoundsScratch);
if (!defined(rectangle)) {
// There is no overlap between this terrain tile and this imagery
// provider. Unless this is the base layer, no skeletons need to be created.
// We stretch texels at the edge of the base layer over the entire globe.
if (!this.isBaseLayer()) {
return false;
}
var baseImageryRectangle = imageryBounds;
var baseTerrainRectangle = tile.rectangle;
rectangle = tileImageryBoundsScratch;
if (baseTerrainRectangle.south >= baseImageryRectangle.north) {
rectangle.north = rectangle.south = baseImageryRectangle.north;
} else if (baseTerrainRectangle.north <= baseImageryRectangle.south) {
rectangle.north = rectangle.south = baseImageryRectangle.south;
}
if (baseTerrainRectangle.west >= baseImageryRectangle.east) {
rectangle.west = rectangle.east = baseImageryRectangle.east;
} else if (baseTerrainRectangle.east <= baseImageryRectangle.west) {
rectangle.west = rectangle.east = baseImageryRectangle.west;
}
}
var latitudeClosestToEquator = 0.0;
if (rectangle.south > 0.0) {
latitudeClosestToEquator = rectangle.south;
} else if (rectangle.north < 0.0) {
latitudeClosestToEquator = rectangle.north;
}
// Compute the required level in the imagery tiling scheme.
// The errorRatio should really be imagerySSE / terrainSSE rather than this hard-coded value.
// But first we need configurable imagery SSE and we need the rendering to be able to handle more
// images attached to a terrain tile than there are available texture units. So that's for the future.
var errorRatio = 1.0;
var targetGeometricError = errorRatio * terrainProvider.getLevelMaximumGeometricError(tile.level);
var imageryLevel = getLevelWithMaximumTexelSpacing(this, targetGeometricError, latitudeClosestToEquator);
imageryLevel = Math.max(0, imageryLevel);
var maximumLevel = imageryProvider.maximumLevel;
if (imageryLevel > maximumLevel) {
imageryLevel = maximumLevel;
}
if (defined(imageryProvider.minimumLevel)) {
var minimumLevel = imageryProvider.minimumLevel;
if (imageryLevel < minimumLevel) {
imageryLevel = minimumLevel;
}
}
var imageryTilingScheme = imageryProvider.tilingScheme;
var northwestTileCoordinates = imageryTilingScheme.positionToTileXY(Rectangle.northwest(rectangle), imageryLevel);
var southeastTileCoordinates = imageryTilingScheme.positionToTileXY(Rectangle.southeast(rectangle), imageryLevel);
// If the southeast corner of the rectangle lies very close to the north or west side
// of the southeast tile, we don't actually need the southernmost or easternmost
// tiles.
// Similarly, if the northwest corner of the rectangle lies very close to the south or east side
// of the northwest tile, we don't actually need the northernmost or westernmost tiles.
// We define "very close" as being within 1/512 of the width of the tile.
var veryCloseX = tile.rectangle.height / 512.0;
var veryCloseY = tile.rectangle.width / 512.0;
var northwestTileRectangle = imageryTilingScheme.tileXYToRectangle(northwestTileCoordinates.x, northwestTileCoordinates.y, imageryLevel);
if (Math.abs(northwestTileRectangle.south - tile.rectangle.north) < veryCloseY && northwestTileCoordinates.y < southeastTileCoordinates.y) {
++northwestTileCoordinates.y;
}
if (Math.abs(northwestTileRectangle.east - tile.rectangle.west) < veryCloseX && northwestTileCoordinates.x < southeastTileCoordinates.x) {
++northwestTileCoordinates.x;
}
var southeastTileRectangle = imageryTilingScheme.tileXYToRectangle(southeastTileCoordinates.x, southeastTileCoordinates.y, imageryLevel);
if (Math.abs(southeastTileRectangle.north - tile.rectangle.south) < veryCloseY && southeastTileCoordinates.y > northwestTileCoordinates.y) {
--southeastTileCoordinates.y;
}
if (Math.abs(southeastTileRectangle.west - tile.rectangle.east) < veryCloseX && southeastTileCoordinates.x > northwestTileCoordinates.x) {
--southeastTileCoordinates.x;
}
// Create TileImagery instances for each imagery tile overlapping this terrain tile.
// We need to do all texture coordinate computations in the imagery tile's tiling scheme.
var terrainRectangle = tile.rectangle;
var imageryRectangle = imageryTilingScheme.tileXYToRectangle(northwestTileCoordinates.x, northwestTileCoordinates.y, imageryLevel);
var clippedImageryRectangle = Rectangle.intersection(imageryRectangle, imageryBounds, clippedRectangleScratch);
var minU;
var maxU = 0.0;
var minV = 1.0;
var maxV;
// If this is the northern-most or western-most tile in the imagery tiling scheme,
// it may not start at the northern or western edge of the terrain tile.
// Calculate where it does start.
if (!this.isBaseLayer() && Math.abs(clippedImageryRectangle.west - tile.rectangle.west) >= veryCloseX) {
maxU = Math.min(1.0, (clippedImageryRectangle.west - terrainRectangle.west) / terrainRectangle.width);
}
if (!this.isBaseLayer() && Math.abs(clippedImageryRectangle.north - tile.rectangle.north) >= veryCloseY) {
minV = Math.max(0.0, (clippedImageryRectangle.north - terrainRectangle.south) / terrainRectangle.height);
}
var initialMinV = minV;
for ( var i = northwestTileCoordinates.x; i <= southeastTileCoordinates.x; i++) {
minU = maxU;
imageryRectangle = imageryTilingScheme.tileXYToRectangle(i, northwestTileCoordinates.y, imageryLevel);
clippedImageryRectangle = Rectangle.intersection(imageryRectangle, imageryBounds, clippedRectangleScratch);
maxU = Math.min(1.0, (clippedImageryRectangle.east - terrainRectangle.west) / terrainRectangle.width);
// If this is the eastern-most imagery tile mapped to this terrain tile,
// and there are more imagery tiles to the east of this one, the maxU
// should be 1.0 to make sure rounding errors don't make the last
// image fall shy of the edge of the terrain tile.
if (i === southeastTileCoordinates.x && (this.isBaseLayer() || Math.abs(clippedImageryRectangle.east - tile.rectangle.east) < veryCloseX)) {
maxU = 1.0;
}
minV = initialMinV;
for ( var j = northwestTileCoordinates.y; j <= southeastTileCoordinates.y; j++) {
maxV = minV;
imageryRectangle = imageryTilingScheme.tileXYToRectangle(i, j, imageryLevel);
clippedImageryRectangle = Rectangle.intersection(imageryRectangle, imageryBounds, clippedRectangleScratch);
minV = Math.max(0.0, (clippedImageryRectangle.south - terrainRectangle.south) / terrainRectangle.height);
// If this is the southern-most imagery tile mapped to this terrain tile,
// and there are more imagery tiles to the south of this one, the minV
// should be 0.0 to make sure rounding errors don't make the last
// image fall shy of the edge of the terrain tile.
if (j === southeastTileCoordinates.y && (this.isBaseLayer() || Math.abs(clippedImageryRectangle.south - tile.rectangle.south) < veryCloseY)) {
minV = 0.0;
}
var texCoordsRectangle = new Cartesian4(minU, minV, maxU, maxV);
var imagery = this.getImageryFromCache(i, j, imageryLevel, imageryRectangle);
surfaceTile.imagery.splice(insertionPoint, 0, new TileImagery(imagery, texCoordsRectangle));
++insertionPoint;
}
}
return true;
};
/**
* Calculate the translation and scale for a particular {@link TileImagery} attached to a
* particular terrain tile.
*
* @private
*
* @param {Tile} tile The terrain tile.
* @param {TileImagery} tileImagery The imagery tile mapping.
* @returns {Cartesian4} The translation and scale where X and Y are the translation and Z and W
* are the scale.
*/
ImageryLayer.prototype._calculateTextureTranslationAndScale = function(tile, tileImagery) {
var imageryRectangle = tileImagery.readyImagery.rectangle;
var terrainRectangle = tile.rectangle;
var terrainWidth = terrainRectangle.width;
var terrainHeight = terrainRectangle.height;
var scaleX = terrainWidth / imageryRectangle.width;
var scaleY = terrainHeight / imageryRectangle.height;
return new Cartesian4(
scaleX * (terrainRectangle.west - imageryRectangle.west) / terrainWidth,
scaleY * (terrainRectangle.south - imageryRectangle.south) / terrainHeight,
scaleX,
scaleY);
};
/**
* Request a particular piece of imagery from the imagery provider. This method handles raising an
* error event if the request fails, and retrying the request if necessary.
*
* @private
*
* @param {Imagery} imagery The imagery to request.
*/
ImageryLayer.prototype._requestImagery = function(imagery) {
var imageryProvider = this._imageryProvider;
var that = this;
function success(image) {
if (!defined(image)) {
return failure();
}
imagery.image = image;
imagery.state = ImageryState.RECEIVED;
TileProviderError.handleSuccess(that._requestImageError);
}
function failure(e) {
// Initially assume failure. handleError may retry, in which case the state will
// change to TRANSITIONING.
imagery.state = ImageryState.FAILED;
var message = 'Failed to obtain image tile X: ' + imagery.x + ' Y: ' + imagery.y + ' Level: ' + imagery.level + '.';
that._requestImageError = TileProviderError.handleError(
that._requestImageError,
imageryProvider,
imageryProvider.errorEvent,
message,
imagery.x, imagery.y, imagery.level,
doRequest);
}
function doRequest() {
imagery.state = ImageryState.TRANSITIONING;
var imagePromise = imageryProvider.requestImage(imagery.x, imagery.y, imagery.level);
if (!defined(imagePromise)) {
// Too many parallel requests, so postpone loading tile.
imagery.state = ImageryState.UNLOADED;
return;
}
if (defined(imageryProvider.getTileCredits)) {
imagery.credits = imageryProvider.getTileCredits(imagery.x, imagery.y, imagery.level);
}
when(imagePromise, success, failure);
}
doRequest();
};
/**
* Create a WebGL texture for a given {@link Imagery} instance.
*
* @private
*
* @param {Context} context The rendered context to use to create textures.
* @param {Imagery} imagery The imagery for which to create a texture.
*/
ImageryLayer.prototype._createTexture = function(context, imagery) {
var imageryProvider = this._imageryProvider;
// If this imagery provider has a discard policy, use it to check if this
// image should be discarded.
if (defined(imageryProvider.tileDiscardPolicy)) {
var discardPolicy = imageryProvider.tileDiscardPolicy;
if (defined(discardPolicy)) {
// If the discard policy is not ready yet, transition back to the
// RECEIVED state and we'll try again next time.
if (!discardPolicy.isReady()) {
imagery.state = ImageryState.RECEIVED;
return;
}
// Mark discarded imagery tiles invalid. Parent imagery will be used instead.
if (discardPolicy.shouldDiscardImage(imagery.image)) {
imagery.state = ImageryState.INVALID;
return;
}
}
}
// Imagery does not need to be discarded, so upload it to WebGL.
var texture = context.createTexture2D({
source : imagery.image,
pixelFormat : imageryProvider.hasAlphaChannel ? PixelFormat.RGBA : PixelFormat.RGB
});
imagery.texture = texture;
imagery.image = undefined;
imagery.state = ImageryState.TEXTURE_LOADED;
};
/**
* Reproject a texture to a {@link GeographicProjection}, if necessary, and generate
* mipmaps for the geographic texture.
*
* @private
*
* @param {Context} context The rendered context to use.
* @param {Imagery} imagery The imagery instance to reproject.
*/
ImageryLayer.prototype._reprojectTexture = function(context, imagery) {
var texture = imagery.texture;
var rectangle = imagery.rectangle;
// Reproject this texture if it is not already in a geographic projection and
// the pixels are more than 1e-5 radians apart. The pixel spacing cutoff
// avoids precision problems in the reprojection transformation while making
// no noticeable difference in the georeferencing of the image.
if (!(this._imageryProvider.tilingScheme instanceof GeographicTilingScheme) &&
rectangle.width / texture.width > 1e-5) {
var reprojectedTexture = reprojectToGeographic(this, context, texture, imagery.rectangle);
texture.destroy();
imagery.texture = texture = reprojectedTexture;
}
// Use mipmaps if this texture has power-of-two dimensions.
if (CesiumMath.isPowerOfTwo(texture.width) && CesiumMath.isPowerOfTwo(texture.height)) {
var mipmapSampler = context.cache.imageryLayer_mipmapSampler;
if (!defined(mipmapSampler)) {
var maximumSupportedAnisotropy = context.maximumTextureFilterAnisotropy;
mipmapSampler = context.cache.imageryLayer_mipmapSampler = context.createSampler({
wrapS : TextureWrap.CLAMP_TO_EDGE,
wrapT : TextureWrap.CLAMP_TO_EDGE,
minificationFilter : TextureMinificationFilter.LINEAR_MIPMAP_LINEAR,
magnificationFilter : TextureMagnificationFilter.LINEAR,
maximumAnisotropy : Math.min(maximumSupportedAnisotropy, defaultValue(this._maximumAnisotropy, maximumSupportedAnisotropy))
});
}
texture.generateMipmap(MipmapHint.NICEST);
texture.sampler = mipmapSampler;
} else {
var nonMipmapSampler = context.cache.imageryLayer_nonMipmapSampler;
if (!defined(nonMipmapSampler)) {
nonMipmapSampler = context.cache.imageryLayer_nonMipmapSampler = context.createSampler({
wrapS : TextureWrap.CLAMP_TO_EDGE,
wrapT : TextureWrap.CLAMP_TO_EDGE,
minificationFilter : TextureMinificationFilter.LINEAR,
magnificationFilter : TextureMagnificationFilter.LINEAR
});
}
texture.sampler = nonMipmapSampler;
}
imagery.state = ImageryState.READY;
};
ImageryLayer.prototype.getImageryFromCache = function(x, y, level, imageryRectangle) {
var cacheKey = getImageryCacheKey(x, y, level);
var imagery = this._imageryCache[cacheKey];
if (!defined(imagery)) {
imagery = new Imagery(this, x, y, level, imageryRectangle);
this._imageryCache[cacheKey] = imagery;
}
imagery.addReference();
return imagery;
};
ImageryLayer.prototype.removeImageryFromCache = function(imagery) {
var cacheKey = getImageryCacheKey(imagery.x, imagery.y, imagery.level);
delete this._imageryCache[cacheKey];
};
function getImageryCacheKey(x, y, level) {
return JSON.stringify([x, y, level]);
}
var uniformMap = {
u_textureDimensions : function() {
return this.textureDimensions;
},
u_texture : function() {
return this.texture;
},
textureDimensions : new Cartesian2(),
texture : undefined
};
var float32ArrayScratch = FeatureDetection.supportsTypedArrays() ? new Float32Array(2 * 64) : undefined;
function reprojectToGeographic(imageryLayer, context, texture, rectangle) {
// This function has gone through a number of iterations, because GPUs are awesome.
//
// Originally, we had a very simple vertex shader and computed the Web Mercator texture coordinates
// per-fragment in the fragment shader. That worked well, except on mobile devices, because
// fragment shaders have limited precision on many mobile devices. The result was smearing artifacts
// at medium zoom levels because different geographic texture coordinates would be reprojected to Web
// Mercator as the same value.
//
// Our solution was to reproject to Web Mercator in the vertex shader instead of the fragment shader.
// This required far more vertex data. With fragment shader reprojection, we only needed a single quad.
// But to achieve the same precision with vertex shader reprojection, we needed a vertex for each
// output pixel. So we used a grid of 256x256 vertices, because most of our imagery
// tiles are 256x256. Fortunately the grid could be created and uploaded to the GPU just once and
// re-used for all reprojections, so the performance was virtually unchanged from our original fragment
// shader approach. See https://github.com/AnalyticalGraphicsInc/cesium/pull/714.
//
// Over a year later, we noticed (https://github.com/AnalyticalGraphicsInc/cesium/issues/2110)
// that our reprojection code was creating a rare but severe artifact on some GPUs (Intel HD 4600
// for one). The problem was that the GLSL sin function on these GPUs had a discontinuity at fine scales in
// a few places.
//
// We solved this by implementing a more reliable sin function based on the CORDIC algorithm
// (https://github.com/AnalyticalGraphicsInc/cesium/pull/2111). Even though this was a fair
// amount of code to be executing per vertex, the performance seemed to be pretty good on most GPUs.
// Unfortunately, on some GPUs, the performance was absolutely terrible
// (https://github.com/AnalyticalGraphicsInc/cesium/issues/2258).
//
// So that brings us to our current solution, the one you see here. Effectively, we compute the Web
// Mercator texture coordinates on the CPU and store the T coordinate with each vertex (the S coordinate
// is the same in Geographic and Web Mercator). To make this faster, we reduced our reprojection mesh
// to be only 2 vertices wide and 64 vertices high. We should have reduced the width to 2 sooner,
// because the extra vertices weren't buying us anything. The height of 64 means we are technically
// doing a slightly less accurate reprojection than we were before, but we can't see the difference
// so it's worth the 4x speedup.
var reproject = context.cache.imageryLayer_reproject;
if (!defined(reproject)) {
reproject = context.cache.imageryLayer_reproject = {
framebuffer : undefined,
vertexArray : undefined,
shaderProgram : undefined,
renderState : undefined,
sampler : undefined,
destroy : function() {
if (defined(this.framebuffer)) {
this.framebuffer.destroy();
}
if (defined(this.vertexArray)) {
this.vertexArray.destroy();
}
if (defined(this.shaderProgram)) {
this.shaderProgram.destroy();
}
}
};
var positions = new Float32Array(2 * 64 * 2);
var index = 0;
for (var j = 0; j < 64; ++j) {
var y = j / 63.0;
positions[index++] = 0.0;
positions[index++] = y;
positions[index++] = 1.0;
positions[index++] = y;
}
var reprojectAttributeIndices = {
position : 0,
webMercatorT : 1
};
var indices = TerrainProvider.getRegularGridIndices(2, 64);
var indexBuffer = context.createIndexBuffer(indices, BufferUsage.STATIC_DRAW, IndexDatatype.UNSIGNED_SHORT);
reproject.vertexArray = context.createVertexArray([
{
index : reprojectAttributeIndices.position,
vertexBuffer : context.createVertexBuffer(positions, BufferUsage.STATIC_DRAW),
componentsPerAttribute : 2
},
{
index : reprojectAttributeIndices.webMercatorT,
vertexBuffer : context.createVertexBuffer(64 * 2 * 4, BufferUsage.STREAM_DRAW),
componentsPerAttribute : 1
}
], indexBuffer);
var vs = new ShaderSource({
sources : [ReprojectWebMercatorVS]
});
reproject.shaderProgram = context.createShaderProgram(vs, ReprojectWebMercatorFS, reprojectAttributeIndices);
reproject.sampler = context.createSampler({
wrapS : TextureWrap.CLAMP_TO_EDGE,
wrapT : TextureWrap.CLAMP_TO_EDGE,
minificationFilter : TextureMinificationFilter.LINEAR,
magnificationFilter : TextureMagnificationFilter.LINEAR
});
}
texture.sampler = reproject.sampler;
var width = texture.width;
var height = texture.height;
uniformMap.textureDimensions.x = width;
uniformMap.textureDimensions.y = height;
uniformMap.texture = texture;
var sinLatitude = Math.sin(rectangle.south);
var southMercatorY = 0.5 * Math.log((1 + sinLatitude) / (1 - sinLatitude));
sinLatitude = Math.sin(rectangle.north);
var northMercatorY = 0.5 * Math.log((1 + sinLatitude) / (1 - sinLatitude));
var oneOverMercatorHeight = 1.0 / (northMercatorY - southMercatorY);
var outputTexture = context.createTexture2D({
width : width,
height : height,
pixelFormat : texture.pixelFormat,
pixelDatatype : texture.pixelDatatype,
preMultiplyAlpha : texture.preMultiplyAlpha
});
// Allocate memory for the mipmaps. Failure to do this before rendering
// to the texture via the FBO, and calling generateMipmap later,
// will result in the texture appearing blank. I can't pretend to
// understand exactly why this is.
outputTexture.generateMipmap(MipmapHint.NICEST);
if (defined(reproject.framebuffer)) {
reproject.framebuffer.destroy();
}
reproject.framebuffer = context.createFramebuffer({
colorTextures : [outputTexture]
});
reproject.framebuffer.destroyAttachments = false;
var south = rectangle.south;
var north = rectangle.north;
var webMercatorT = float32ArrayScratch;
var outputIndex = 0;
for (var webMercatorTIndex = 0; webMercatorTIndex < 64; ++webMercatorTIndex) {
var fraction = webMercatorTIndex / 63.0;
var latitude = CesiumMath.lerp(south, north, fraction);
sinLatitude = Math.sin(latitude);
var mercatorY = 0.5 * Math.log((1.0 + sinLatitude) / (1.0 - sinLatitude));
var mercatorFraction = (mercatorY - southMercatorY) * oneOverMercatorHeight;
webMercatorT[outputIndex++] = mercatorFraction;
webMercatorT[outputIndex++] = mercatorFraction;
}
reproject.vertexArray.getAttribute(1).vertexBuffer.copyFromArrayView(webMercatorT);
var command = new ClearCommand({
color : Color.BLACK,
framebuffer : reproject.framebuffer
});
command.execute(context);
if ((!defined(reproject.renderState)) ||
(reproject.renderState.viewport.width !== width) ||
(reproject.renderState.viewport.height !== height)) {
reproject.renderState = context.createRenderState({
viewport : new BoundingRectangle(0, 0, width, height)
});
}
var drawCommand = new DrawCommand({
framebuffer : reproject.framebuffer,
shaderProgram : reproject.shaderProgram,
renderState : reproject.renderState,
primitiveType : PrimitiveType.TRIANGLES,
vertexArray : reproject.vertexArray,
uniformMap : uniformMap
});
drawCommand.execute(context);
return outputTexture;
}
/**
* Gets the level with the specified world coordinate spacing between texels, or less.
*
* @param {Number} texelSpacing The texel spacing for which to find a corresponding level.
* @param {Number} latitudeClosestToEquator The latitude closest to the equator that we're concerned with.
* @returns {Number} The level with the specified texel spacing or less.
*/
function getLevelWithMaximumTexelSpacing(layer, texelSpacing, latitudeClosestToEquator) {
// PERFORMANCE_IDEA: factor out the stuff that doesn't change.
var imageryProvider = layer._imageryProvider;
var tilingScheme = imageryProvider.tilingScheme;
var ellipsoid = tilingScheme.ellipsoid;
var latitudeFactor = !(layer._imageryProvider.tilingScheme instanceof GeographicTilingScheme) ? Math.cos(latitudeClosestToEquator) : 1.0;
var tilingSchemeRectangle = tilingScheme.rectangle;
var levelZeroMaximumTexelSpacing = ellipsoid.maximumRadius * tilingSchemeRectangle.width * latitudeFactor / (imageryProvider.tileWidth * tilingScheme.getNumberOfXTilesAtLevel(0));
var twoToTheLevelPower = levelZeroMaximumTexelSpacing / texelSpacing;
var level = Math.log(twoToTheLevelPower) / Math.log(2);
var rounded = Math.round(level);
return rounded | 0;
}
return ImageryLayer;
});