import Cartesian2 from "../Core/Cartesian2.js";
import Cartesian4 from "../Core/Cartesian4.js";
import defaultValue from "../Core/defaultValue.js";
import defined from "../Core/defined.js";
import destroyObject from "../Core/destroyObject.js";
import DeveloperError from "../Core/DeveloperError.js";
import FeatureDetection from "../Core/FeatureDetection.js";
import GeographicProjection from "../Core/GeographicProjection.js";
import IndexDatatype from "../Core/IndexDatatype.js";
import CesiumMath from "../Core/Math.js";
import PixelFormat from "../Core/PixelFormat.js";
import Rectangle from "../Core/Rectangle.js";
import Request from "../Core/Request.js";
import RequestState from "../Core/RequestState.js";
import RequestType from "../Core/RequestType.js";
import TerrainProvider from "../Core/TerrainProvider.js";
import TileProviderError from "../Core/TileProviderError.js";
import WebMercatorProjection from "../Core/WebMercatorProjection.js";
import Buffer from "../Renderer/Buffer.js";
import BufferUsage from "../Renderer/BufferUsage.js";
import ComputeCommand from "../Renderer/ComputeCommand.js";
import ContextLimits from "../Renderer/ContextLimits.js";
import MipmapHint from "../Renderer/MipmapHint.js";
import Sampler from "../Renderer/Sampler.js";
import ShaderProgram from "../Renderer/ShaderProgram.js";
import ShaderSource from "../Renderer/ShaderSource.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 ReprojectWebMercatorFS from "../Shaders/ReprojectWebMercatorFS.js";
import ReprojectWebMercatorVS from "../Shaders/ReprojectWebMercatorVS.js";
import when from "../ThirdParty/when.js";
import Imagery from "./Imagery.js";
import ImagerySplitDirection from "./ImagerySplitDirection.js";
import ImageryState from "./ImageryState.js";
import TileImagery from "./TileImagery.js";
/**
* 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.nightAlpha=1.0] The alpha blending value of this layer on the night side of the globe, 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. This only takes effect when <code>enableLighting</code> is <code>true</code>.
* @param {Number|Function} [options.dayAlpha=1.0] The alpha blending value of this layer on the day side of the globe, 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. This only takes effect when <code>enableLighting</code> is <code>true</code>.
* @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 {ImagerySplitDirection|Function} [options.splitDirection=ImagerySplitDirection.NONE] The {@link ImagerySplitDirection} split to apply to this layer.
* @param {TextureMinificationFilter} [options.minificationFilter=TextureMinificationFilter.LINEAR] The
* texture minification filter to apply to this layer. Possible values
* are <code>TextureMinificationFilter.LINEAR</code> and
* <code>TextureMinificationFilter.NEAREST</code>.
* @param {TextureMagnificationFilter} [options.magnificationFilter=TextureMagnificationFilter.LINEAR] The
* texture minification filter to apply to this layer. Possible values
* are <code>TextureMagnificationFilter.LINEAR</code> and
* <code>TextureMagnificationFilter.NEAREST</code>.
* @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.
* @param {Rectangle} [options.cutoutRectangle] Cartographic rectangle for cutting out a portion of this ImageryLayer.
* @param {Color} [options.colorToAlpha] Color to be used as alpha.
* @param {Number} [options.colorToAlphaThreshold=0.004] Threshold for color-to-alpha.
*/
function ImageryLayer(imageryProvider, options) {
this._imageryProvider = imageryProvider;
options = defaultValue(options, defaultValue.EMPTY_OBJECT);
/**
* 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 alpha blending value of this layer on the night side of the globe, with 0.0 representing fully transparent and
* 1.0 representing fully opaque. This only takes effect when {@link Globe#enableLighting} is <code>true</code>.
*
* @type {Number}
* @default 1.0
*/
this.nightAlpha = defaultValue(
options.nightAlpha,
defaultValue(imageryProvider.defaultNightAlpha, 1.0)
);
/**
* The alpha blending value of this layer on the day side of the globe, with 0.0 representing fully transparent and
* 1.0 representing fully opaque. This only takes effect when {@link Globe#enableLighting} is <code>true</code>.
*
* @type {Number}
* @default 1.0
*/
this.dayAlpha = defaultValue(
options.dayAlpha,
defaultValue(imageryProvider.defaultDayAlpha, 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)
);
/**
* The {@link ImagerySplitDirection} to apply to this layer.
*
* @type {ImagerySplitDirection}
* @default {@link ImageryLayer.DEFAULT_SPLIT}
*/
this.splitDirection = defaultValue(
options.splitDirection,
defaultValue(imageryProvider.defaultSplit, ImageryLayer.DEFAULT_SPLIT)
);
/**
* The {@link TextureMinificationFilter} to apply to this layer.
* Possible values are {@link TextureMinificationFilter.LINEAR} (the default)
* and {@link TextureMinificationFilter.NEAREST}.
*
* To take effect, this property must be set immediately after adding the imagery layer.
* Once a texture is loaded it won't be possible to change the texture filter used.
*
* @type {TextureMinificationFilter}
* @default {@link ImageryLayer.DEFAULT_MINIFICATION_FILTER}
*/
this.minificationFilter = defaultValue(
options.minificationFilter,
defaultValue(
imageryProvider.defaultMinificationFilter,
ImageryLayer.DEFAULT_MINIFICATION_FILTER
)
);
/**
* The {@link TextureMagnificationFilter} to apply to this layer.
* Possible values are {@link TextureMagnificationFilter.LINEAR} (the default)
* and {@link TextureMagnificationFilter.NEAREST}.
*
* To take effect, this property must be set immediately after adding the imagery layer.
* Once a texture is loaded it won't be possible to change the texture filter used.
*
* @type {TextureMagnificationFilter}
* @default {@link ImageryLayer.DEFAULT_MAGNIFICATION_FILTER}
*/
this.magnificationFilter = defaultValue(
options.magnificationFilter,
defaultValue(
imageryProvider.defaultMagnificationFilter,
ImageryLayer.DEFAULT_MAGNIFICATION_FILTER
)
);
/**
* 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;
this._reprojectComputeCommands = [];
/**
* Rectangle cutout in this layer of imagery.
*
* @type {Rectangle}
*/
this.cutoutRectangle = options.cutoutRectangle;
/**
* Color value that should be set to transparent.
*
* @type {Color}
*/
this.colorToAlpha = options.colorToAlpha;
/**
* Normalized (0-1) threshold for color-to-alpha.
*
* @type {Number}
*/
this.colorToAlphaThreshold = defaultValue(
options.colorToAlphaThreshold,
ImageryLayer.DEFAULT_APPLY_COLOR_TO_ALPHA_THRESHOLD
);
}
Object.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;
/**
* This value is used as the default split for the imagery layer if one is not provided during construction
* or by the imagery provider.
* @type {ImagerySplitDirection}
* @default ImagerySplitDirection.NONE
*/
ImageryLayer.DEFAULT_SPLIT = ImagerySplitDirection.NONE;
/**
* This value is used as the default texture minification filter for the imagery layer if one is not provided
* during construction or by the imagery provider.
* @type {TextureMinificationFilter}
* @default TextureMinificationFilter.LINEAR
*/
ImageryLayer.DEFAULT_MINIFICATION_FILTER = TextureMinificationFilter.LINEAR;
/**
* This value is used as the default texture magnification filter for the imagery layer if one is not provided
* during construction or by the imagery provider.
* @type {TextureMagnificationFilter}
* @default TextureMagnificationFilter.LINEAR
*/
ImageryLayer.DEFAULT_MAGNIFICATION_FILTER = TextureMagnificationFilter.LINEAR;
/**
* This value is used as the default threshold for color-to-alpha if one is not provided
* during construction or by the imagery provider.
* @type {Number}
* @default 0.004
*/
ImageryLayer.DEFAULT_APPLY_COLOR_TO_ALPHA_THRESHOLD = 0.004;
/**
* 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.
*
* @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
*
*
* @example
* imageryLayer = imageryLayer && imageryLayer.destroy();
*
* @see ImageryLayer#isDestroyed
*/
ImageryLayer.prototype.destroy = function () {
return destroyObject(this);
};
var imageryBoundsScratch = new Rectangle();
var tileImageryBoundsScratch = new Rectangle();
var clippedRectangleScratch = new Rectangle();
var terrainRectangleScratch = new Rectangle();
/**
* Computes the intersection of this layer's rectangle with the imagery provider's availability rectangle,
* producing the overall bounds of imagery that can be produced by this layer.
*
* @returns {Promise.<Rectangle>} A promise to a rectangle which defines the overall bounds of imagery that can be produced by this layer.
*
* @example
* // Zoom to an imagery layer.
* imageryLayer.getViewableRectangle().then(function (rectangle) {
* return camera.flyTo({
* destination: rectangle
* });
* });
*/
ImageryLayer.prototype.getViewableRectangle = function () {
var imageryProvider = this._imageryProvider;
var rectangle = this._rectangle;
return imageryProvider.readyPromise.then(function () {
return Rectangle.intersection(imageryProvider.rectangle, 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 list.
* @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;
}
// Use Web Mercator for our texture coordinate computations if this imagery layer uses
// that projection and the terrain tile falls entirely inside the valid bounds of the
// projection.
var useWebMercatorT =
imageryProvider.tilingScheme.projection instanceof WebMercatorProjection &&
tile.rectangle.north < WebMercatorProjection.MaximumLatitude &&
tile.rectangle.south > -WebMercatorProjection.MaximumLatitude;
// 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;
} else {
rectangle.south = Math.max(
baseTerrainRectangle.south,
baseImageryRectangle.south
);
rectangle.north = Math.min(
baseTerrainRectangle.north,
baseImageryRectangle.north
);
}
if (baseTerrainRectangle.west >= baseImageryRectangle.east) {
rectangle.west = rectangle.east = baseImageryRectangle.east;
} else if (baseTerrainRectangle.east <= baseImageryRectangle.west) {
rectangle.west = rectangle.east = baseImageryRectangle.west;
} else {
rectangle.west = Math.max(
baseTerrainRectangle.west,
baseImageryRectangle.west
);
rectangle.east = Math.min(
baseTerrainRectangle.east,
baseImageryRectangle.east
);
}
}
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.width / 512.0;
var veryCloseY = tile.rectangle.height / 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 = Rectangle.clone(
tile.rectangle,
terrainRectangleScratch
);
var imageryRectangle = imageryTilingScheme.tileXYToRectangle(
northwestTileCoordinates.x,
northwestTileCoordinates.y,
imageryLevel
);
var clippedImageryRectangle = Rectangle.intersection(
imageryRectangle,
imageryBounds,
clippedRectangleScratch
);
var imageryTileXYToRectangle;
if (useWebMercatorT) {
imageryTilingScheme.rectangleToNativeRectangle(
terrainRectangle,
terrainRectangle
);
imageryTilingScheme.rectangleToNativeRectangle(
imageryRectangle,
imageryRectangle
);
imageryTilingScheme.rectangleToNativeRectangle(
clippedImageryRectangle,
clippedImageryRectangle
);
imageryTilingScheme.rectangleToNativeRectangle(
imageryBounds,
imageryBounds
);
imageryTileXYToRectangle = imageryTilingScheme.tileXYToNativeRectangle.bind(
imageryTilingScheme
);
veryCloseX = terrainRectangle.width / 512.0;
veryCloseY = terrainRectangle.height / 512.0;
} else {
imageryTileXYToRectangle = imageryTilingScheme.tileXYToRectangle.bind(
imageryTilingScheme
);
}
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 - terrainRectangle.west) >= veryCloseX
) {
maxU = Math.min(
1.0,
(clippedImageryRectangle.west - terrainRectangle.west) /
terrainRectangle.width
);
}
if (
!this.isBaseLayer() &&
Math.abs(clippedImageryRectangle.north - terrainRectangle.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 = imageryTileXYToRectangle(
i,
northwestTileCoordinates.y,
imageryLevel
);
clippedImageryRectangle = Rectangle.simpleIntersection(
imageryRectangle,
imageryBounds,
clippedRectangleScratch
);
if (!defined(clippedImageryRectangle)) {
continue;
}
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 - terrainRectangle.east) <
veryCloseX)
) {
maxU = 1.0;
}
minV = initialMinV;
for (
var j = northwestTileCoordinates.y;
j <= southeastTileCoordinates.y;
j++
) {
maxV = minV;
imageryRectangle = imageryTileXYToRectangle(i, j, imageryLevel);
clippedImageryRectangle = Rectangle.simpleIntersection(
imageryRectangle,
imageryBounds,
clippedRectangleScratch
);
if (!defined(clippedImageryRectangle)) {
continue;
}
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 - terrainRectangle.south) <
veryCloseY)
) {
minV = 0.0;
}
var texCoordsRectangle = new Cartesian4(minU, minV, maxU, maxV);
var imagery = this.getImageryFromCache(i, j, imageryLevel);
surfaceTile.imagery.splice(
insertionPoint,
0,
new TileImagery(imagery, texCoordsRectangle, useWebMercatorT)
);
++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;
if (tileImagery.useWebMercatorT) {
var tilingScheme =
tileImagery.readyImagery.imageryLayer.imageryProvider.tilingScheme;
imageryRectangle = tilingScheme.rectangleToNativeRectangle(
imageryRectangle,
imageryBoundsScratch
);
terrainRectangle = tilingScheme.rectangleToNativeRectangle(
terrainRectangle,
terrainRectangleScratch
);
}
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;
imagery.request = undefined;
TileProviderError.handleSuccess(that._requestImageError);
}
function failure(e) {
if (imagery.request.state === RequestState.CANCELLED) {
// Cancelled due to low priority - try again later.
imagery.state = ImageryState.UNLOADED;
imagery.request = undefined;
return;
}
// Initially assume failure. handleError may retry, in which case the state will
// change to TRANSITIONING.
imagery.state = ImageryState.FAILED;
imagery.request = undefined;
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,
e
);
}
function doRequest() {
var request = new Request({
throttle: false,
throttleByServer: true,
type: RequestType.IMAGERY,
});
imagery.request = request;
imagery.state = ImageryState.TRANSITIONING;
var imagePromise = imageryProvider.requestImage(
imagery.x,
imagery.y,
imagery.level,
request
);
if (!defined(imagePromise)) {
// Too many parallel requests, so postpone loading tile.
imagery.state = ImageryState.UNLOADED;
imagery.request = undefined;
return;
}
if (defined(imageryProvider.getTileCredits)) {
imagery.credits = imageryProvider.getTileCredits(
imagery.x,
imagery.y,
imagery.level
);
}
when(imagePromise, success, failure);
}
doRequest();
};
ImageryLayer.prototype._createTextureWebGL = function (context, imagery) {
var sampler = new Sampler({
minificationFilter: this.minificationFilter,
magnificationFilter: this.magnificationFilter,
});
var image = imagery.image;
if (defined(image.internalFormat)) {
return new Texture({
context: context,
pixelFormat: image.internalFormat,
width: image.width,
height: image.height,
source: {
arrayBufferView: image.bufferView,
},
sampler: sampler,
});
}
return new Texture({
context: context,
source: image,
pixelFormat: this._imageryProvider.hasAlphaChannel
? PixelFormat.RGBA
: PixelFormat.RGB,
sampler: sampler,
});
};
/**
* 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;
var image = imagery.image;
// 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(image)) {
imagery.state = ImageryState.INVALID;
return;
}
}
}
//>>includeStart('debug', pragmas.debug);
if (
this.minificationFilter !== TextureMinificationFilter.NEAREST &&
this.minificationFilter !== TextureMinificationFilter.LINEAR
) {
throw new DeveloperError(
"ImageryLayer minification filter must be NEAREST or LINEAR"
);
}
//>>includeEnd('debug');
// Imagery does not need to be discarded, so upload it to WebGL.
var texture = this._createTextureWebGL(context, imagery);
if (
imageryProvider.tilingScheme.projection instanceof WebMercatorProjection
) {
imagery.textureWebMercator = texture;
} else {
imagery.texture = texture;
}
imagery.image = undefined;
imagery.state = ImageryState.TEXTURE_LOADED;
};
function getSamplerKey(
minificationFilter,
magnificationFilter,
maximumAnisotropy
) {
return (
minificationFilter + ":" + magnificationFilter + ":" + maximumAnisotropy
);
}
ImageryLayer.prototype._finalizeReprojectTexture = function (context, texture) {
var minificationFilter = this.minificationFilter;
var magnificationFilter = this.magnificationFilter;
var usesLinearTextureFilter =
minificationFilter === TextureMinificationFilter.LINEAR &&
magnificationFilter === TextureMagnificationFilter.LINEAR;
// Use mipmaps if this texture has power-of-two dimensions.
// In addition, mipmaps are only generated if the texture filters are both LINEAR.
if (
usesLinearTextureFilter &&
!PixelFormat.isCompressedFormat(texture.pixelFormat) &&
CesiumMath.isPowerOfTwo(texture.width) &&
CesiumMath.isPowerOfTwo(texture.height)
) {
minificationFilter = TextureMinificationFilter.LINEAR_MIPMAP_LINEAR;
var maximumSupportedAnisotropy =
ContextLimits.maximumTextureFilterAnisotropy;
var maximumAnisotropy = Math.min(
maximumSupportedAnisotropy,
defaultValue(this._maximumAnisotropy, maximumSupportedAnisotropy)
);
var mipmapSamplerKey = getSamplerKey(
minificationFilter,
magnificationFilter,
maximumAnisotropy
);
var mipmapSamplers = context.cache.imageryLayerMipmapSamplers;
if (!defined(mipmapSamplers)) {
mipmapSamplers = {};
context.cache.imageryLayerMipmapSamplers = mipmapSamplers;
}
var mipmapSampler = mipmapSamplers[mipmapSamplerKey];
if (!defined(mipmapSampler)) {
mipmapSampler = mipmapSamplers[mipmapSamplerKey] = new Sampler({
wrapS: TextureWrap.CLAMP_TO_EDGE,
wrapT: TextureWrap.CLAMP_TO_EDGE,
minificationFilter: minificationFilter,
magnificationFilter: magnificationFilter,
maximumAnisotropy: maximumAnisotropy,
});
}
texture.generateMipmap(MipmapHint.NICEST);
texture.sampler = mipmapSampler;
} else {
var nonMipmapSamplerKey = getSamplerKey(
minificationFilter,
magnificationFilter,
0
);
var nonMipmapSamplers = context.cache.imageryLayerNonMipmapSamplers;
if (!defined(nonMipmapSamplers)) {
nonMipmapSamplers = {};
context.cache.imageryLayerNonMipmapSamplers = nonMipmapSamplers;
}
var nonMipmapSampler = nonMipmapSamplers[nonMipmapSamplerKey];
if (!defined(nonMipmapSampler)) {
nonMipmapSampler = nonMipmapSamplers[nonMipmapSamplerKey] = new Sampler({
wrapS: TextureWrap.CLAMP_TO_EDGE,
wrapT: TextureWrap.CLAMP_TO_EDGE,
minificationFilter: minificationFilter,
magnificationFilter: magnificationFilter,
});
}
texture.sampler = nonMipmapSampler;
}
};
/**
* Enqueues a command re-projecting a texture to a {@link GeographicProjection} on the next update, if necessary, and generate
* mipmaps for the geographic texture.
*
* @private
*
* @param {FrameState} frameState The frameState.
* @param {Imagery} imagery The imagery instance to reproject.
* @param {Boolean} [needGeographicProjection=true] True to reproject to geographic, or false if Web Mercator is fine.
*/
ImageryLayer.prototype._reprojectTexture = function (
frameState,
imagery,
needGeographicProjection
) {
var texture = imagery.textureWebMercator || imagery.texture;
var rectangle = imagery.rectangle;
var context = frameState.context;
needGeographicProjection = defaultValue(needGeographicProjection, true);
// 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 (
needGeographicProjection &&
!(
this._imageryProvider.tilingScheme.projection instanceof
GeographicProjection
) &&
rectangle.width / texture.width > 1e-5
) {
var that = this;
imagery.addReference();
var computeCommand = new ComputeCommand({
persists: true,
owner: this,
// Update render resources right before execution instead of now.
// This allows different ImageryLayers to share the same vao and buffers.
preExecute: function (command) {
reprojectToGeographic(command, context, texture, imagery.rectangle);
},
postExecute: function (outputTexture) {
imagery.texture = outputTexture;
that._finalizeReprojectTexture(context, outputTexture);
imagery.state = ImageryState.READY;
imagery.releaseReference();
},
canceled: function () {
imagery.state = ImageryState.TEXTURE_LOADED;
imagery.releaseReference();
},
});
this._reprojectComputeCommands.push(computeCommand);
} else {
if (needGeographicProjection) {
imagery.texture = texture;
}
this._finalizeReprojectTexture(context, texture);
imagery.state = ImageryState.READY;
}
};
/**
* Updates frame state to execute any queued texture re-projections.
*
* @private
*
* @param {FrameState} frameState The frameState.
*/
ImageryLayer.prototype.queueReprojectionCommands = function (frameState) {
var computeCommands = this._reprojectComputeCommands;
var length = computeCommands.length;
for (var i = 0; i < length; ++i) {
frameState.commandList.push(computeCommands[i]);
}
computeCommands.length = 0;
};
/**
* Cancels re-projection commands queued for the next frame.
*
* @private
*/
ImageryLayer.prototype.cancelReprojections = function () {
this._reprojectComputeCommands.forEach(function (command) {
if (defined(command.canceled)) {
command.canceled();
}
});
this._reprojectComputeCommands.length = 0;
};
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(command, 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/CesiumGS/cesium/pull/714.
//
// Over a year later, we noticed (https://github.com/CesiumGS/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/CesiumGS/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/CesiumGS/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 = {
vertexArray: undefined,
shaderProgram: 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 = Buffer.createIndexBuffer({
context: context,
typedArray: indices,
usage: BufferUsage.STATIC_DRAW,
indexDatatype: IndexDatatype.UNSIGNED_SHORT,
});
reproject.vertexArray = new VertexArray({
context: context,
attributes: [
{
index: reprojectAttributeIndices.position,
vertexBuffer: Buffer.createVertexBuffer({
context: context,
typedArray: positions,
usage: BufferUsage.STATIC_DRAW,
}),
componentsPerAttribute: 2,
},
{
index: reprojectAttributeIndices.webMercatorT,
vertexBuffer: Buffer.createVertexBuffer({
context: context,
sizeInBytes: 64 * 2 * 4,
usage: BufferUsage.STREAM_DRAW,
}),
componentsPerAttribute: 1,
},
],
indexBuffer: indexBuffer,
});
var vs = new ShaderSource({
sources: [ReprojectWebMercatorVS],
});
reproject.shaderProgram = ShaderProgram.fromCache({
context: context,
vertexShaderSource: vs,
fragmentShaderSource: ReprojectWebMercatorFS,
attributeLocations: reprojectAttributeIndices,
});
reproject.sampler = new Sampler({
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 = new Texture({
context: context,
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.
if (CesiumMath.isPowerOfTwo(width) && CesiumMath.isPowerOfTwo(height)) {
outputTexture.generateMipmap(MipmapHint.NICEST);
}
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);
command.shaderProgram = reproject.shaderProgram;
command.outputTexture = outputTexture;
command.uniformMap = uniformMap;
command.vertexArray = reproject.vertexArray;
}
/**
* Gets the level with the specified world coordinate spacing between texels, or less.
*
* @param {ImageryLayer} layer The imagery layer to use.
* @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.
* @private
*/
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.projection instanceof
GeographicProjection
)
? 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;
}
export default ImageryLayer;
