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import Cartesian3 from "./Cartesian3.js";
import Check from "./Check.js";
import Frozen from "./Frozen.js";
import defined from "./defined.js";
import DeveloperError from "./DeveloperError.js";
import GeographicProjection from "./GeographicProjection.js";
import HeightmapEncoding from "./HeightmapEncoding.js";
import HeightmapTessellator from "./HeightmapTessellator.js";
import CesiumMath from "./Math.js";
import OrientedBoundingBox from "./OrientedBoundingBox.js";
import Rectangle from "./Rectangle.js";
import TaskProcessor from "./TaskProcessor.js";
import TerrainData from "./TerrainData.js";
import TerrainEncoding from "./TerrainEncoding.js";
import TerrainMesh from "./TerrainMesh.js";
import TerrainProvider from "./TerrainProvider.js";
/**
* Terrain data for a single tile where the terrain data is represented as a heightmap. A heightmap
* is a rectangular array of heights in row-major order from north to south and west to east.
*
* @alias HeightmapTerrainData
* @constructor
*
* @param {object} options Object with the following properties:
* @param {Int8Array|Uint8Array|Int16Array|Uint16Array|Int32Array|Uint32Array|Float32Array|Float64Array} options.buffer The buffer containing height data.
* @param {number} options.width The width (longitude direction) of the heightmap, in samples.
* @param {number} options.height The height (latitude direction) of the heightmap, in samples.
* @param {number} [options.childTileMask=15] A bit mask indicating which of this tile's four children exist.
* If a child's bit is set, geometry will be requested for that tile as well when it
* is needed. If the bit is cleared, the child tile is not requested and geometry is
* instead upsampled from the parent. The bit values are as follows:
* <table>
* <tr><th>Bit Position</th><th>Bit Value</th><th>Child Tile</th></tr>
* <tr><td>0</td><td>1</td><td>Southwest</td></tr>
* <tr><td>1</td><td>2</td><td>Southeast</td></tr>
* <tr><td>2</td><td>4</td><td>Northwest</td></tr>
* <tr><td>3</td><td>8</td><td>Northeast</td></tr>
* </table>
* @param {Uint8Array} [options.waterMask] The water mask included in this terrain data, if any. A water mask is a square
* Uint8Array or image where a value of 255 indicates water and a value of 0 indicates land.
* Values in between 0 and 255 are allowed as well to smoothly blend between land and water.
* @param {object} [options.structure] An object describing the structure of the height data.
* @param {number} [options.structure.heightScale=1.0] The factor by which to multiply height samples in order to obtain
* the height above the heightOffset, in meters. The heightOffset is added to the resulting
* height after multiplying by the scale.
* @param {number} [options.structure.heightOffset=0.0] The offset to add to the scaled height to obtain the final
* height in meters. The offset is added after the height sample is multiplied by the
* heightScale.
* @param {number} [options.structure.elementsPerHeight=1] The number of elements in the buffer that make up a single height
* sample. This is usually 1, indicating that each element is a separate height sample. If
* it is greater than 1, that number of elements together form the height sample, which is
* computed according to the structure.elementMultiplier and structure.isBigEndian properties.
* @param {number} [options.structure.stride=1] The number of elements to skip to get from the first element of
* one height to the first element of the next height.
* @param {number} [options.structure.elementMultiplier=256.0] The multiplier used to compute the height value when the
* stride property is greater than 1. For example, if the stride is 4 and the strideMultiplier
* is 256, the height is computed as follows:
* `height = buffer[index] + buffer[index + 1] * 256 + buffer[index + 2] * 256 * 256 + buffer[index + 3] * 256 * 256 * 256`
* This is assuming that the isBigEndian property is false. If it is true, the order of the
* elements is reversed.
* @param {boolean} [options.structure.isBigEndian=false] Indicates endianness of the elements in the buffer when the
* stride property is greater than 1. If this property is false, the first element is the
* low-order element. If it is true, the first element is the high-order element.
* @param {number} [options.structure.lowestEncodedHeight] The lowest value that can be stored in the height buffer. Any heights that are lower
* than this value after encoding with the `heightScale` and `heightOffset` are clamped to this value. For example, if the height
* buffer is a `Uint16Array`, this value should be 0 because a `Uint16Array` cannot store negative numbers. If this parameter is
* not specified, no minimum value is enforced.
* @param {number} [options.structure.highestEncodedHeight] The highest value that can be stored in the height buffer. Any heights that are higher
* than this value after encoding with the `heightScale` and `heightOffset` are clamped to this value. For example, if the height
* buffer is a `Uint16Array`, this value should be `256 * 256 - 1` or 65535 because a `Uint16Array` cannot store numbers larger
* than 65535. If this parameter is not specified, no maximum value is enforced.
* @param {HeightmapEncoding} [options.encoding=HeightmapEncoding.NONE] The encoding that is used on the buffer.
* @param {boolean} [options.createdByUpsampling=false] True if this instance was created by upsampling another instance;
* otherwise, false.
*
*
* @example
* const buffer = ...
* const heightBuffer = new Uint16Array(buffer, 0, that._heightmapWidth * that._heightmapWidth);
* const childTileMask = new Uint8Array(buffer, heightBuffer.byteLength, 1)[0];
* const waterMask = new Uint8Array(buffer, heightBuffer.byteLength + 1, buffer.byteLength - heightBuffer.byteLength - 1);
* const terrainData = new Cesium.HeightmapTerrainData({
* buffer : heightBuffer,
* width : 65,
* height : 65,
* childTileMask : childTileMask,
* waterMask : waterMask
* });
*
* @see TerrainData
* @see QuantizedMeshTerrainData
* @see GoogleEarthEnterpriseTerrainData
*/
function HeightmapTerrainData(options) {
options = options ?? Frozen.EMPTY_OBJECT;
//>>includeStart('debug', pragmas.debug);
Check.typeOf.object("options.buffer", options.buffer);
Check.typeOf.number("options.width", options.width);
Check.typeOf.number("options.height", options.height);
//>>includeEnd('debug');
this._buffer = options.buffer;
this._width = options.width;
this._height = options.height;
this._childTileMask = options.childTileMask ?? 15;
this._encoding = options.encoding ?? HeightmapEncoding.NONE;
const defaultStructure = HeightmapTessellator.DEFAULT_STRUCTURE;
let structure = options.structure;
if (!defined(structure)) {
structure = defaultStructure;
} else if (structure !== defaultStructure) {
structure.heightScale =
structure.heightScale ?? defaultStructure.heightScale;
structure.heightOffset =
structure.heightOffset ?? defaultStructure.heightOffset;
structure.elementsPerHeight =
structure.elementsPerHeight ?? defaultStructure.elementsPerHeight;
structure.stride = structure.stride ?? defaultStructure.stride;
structure.elementMultiplier =
structure.elementMultiplier ?? defaultStructure.elementMultiplier;
structure.isBigEndian =
structure.isBigEndian ?? defaultStructure.isBigEndian;
}
this._structure = structure;
this._createdByUpsampling = options.createdByUpsampling ?? false;
this._waterMask = options.waterMask;
this._skirtHeight = undefined;
this._bufferType =
this._encoding === HeightmapEncoding.LERC
? Float32Array
: this._buffer.constructor;
this._mesh = undefined;
}
Object.defineProperties(HeightmapTerrainData.prototype, {
/**
* An array of credits for this tile.
* @memberof HeightmapTerrainData.prototype
* @type {Credit[]}
*/
credits: {
get: function () {
return undefined;
},
},
/**
* The water mask included in this terrain data, if any. A water mask is a square
* Uint8Array or image where a value of 255 indicates water and a value of 0 indicates land.
* Values in between 0 and 255 are allowed as well to smoothly blend between land and water.
* @memberof HeightmapTerrainData.prototype
* @type {Uint8Array|HTMLImageElement|HTMLCanvasElement|ImageBitmap|undefined}
*/
waterMask: {
get: function () {
return this._waterMask;
},
},
childTileMask: {
get: function () {
return this._childTileMask;
},
},
});
const createMeshTaskName = "createVerticesFromHeightmap";
const createMeshTaskProcessorNoThrottle = new TaskProcessor(createMeshTaskName);
const createMeshTaskProcessorThrottle = new TaskProcessor(
createMeshTaskName,
TerrainData.maximumAsynchronousTasks,
);
/**
* Creates a {@link TerrainMesh} from this terrain data.
*
* @private
*
* @param {object} options Object with the following properties:
* @param {TilingScheme} options.tilingScheme The tiling scheme to which this tile belongs.
* @param {number} options.x The X coordinate of the tile for which to create the terrain data.
* @param {number} options.y The Y coordinate of the tile for which to create the terrain data.
* @param {number} options.level The level of the tile for which to create the terrain data.
* @param {number} [options.exaggeration=1.0] The scale used to exaggerate the terrain.
* @param {number} [options.exaggerationRelativeHeight=0.0] The height relative to which terrain is exaggerated.
* @param {boolean} [options.throttle=true] If true, indicates that this operation will need to be retried if too many asynchronous mesh creations are already in progress.
* @returns {Promise<TerrainMesh>|undefined} A promise for the terrain mesh, or undefined if too many
* asynchronous mesh creations are already in progress and the operation should
* be retried later.
*/
HeightmapTerrainData.prototype.createMesh = function (options) {
options = options ?? Frozen.EMPTY_OBJECT;
//>>includeStart('debug', pragmas.debug);
Check.typeOf.object("options.tilingScheme", options.tilingScheme);
Check.typeOf.number("options.x", options.x);
Check.typeOf.number("options.y", options.y);
Check.typeOf.number("options.level", options.level);
//>>includeEnd('debug');
const tilingScheme = options.tilingScheme;
const x = options.x;
const y = options.y;
const level = options.level;
const exaggeration = options.exaggeration ?? 1.0;
const exaggerationRelativeHeight = options.exaggerationRelativeHeight ?? 0.0;
const throttle = options.throttle ?? true;
const ellipsoid = tilingScheme.ellipsoid;
const nativeRectangle = tilingScheme.tileXYToNativeRectangle(x, y, level);
const rectangle = tilingScheme.tileXYToRectangle(x, y, level);
// Compute the center of the tile for RTC rendering.
const center = ellipsoid.cartographicToCartesian(Rectangle.center(rectangle));
const structure = this._structure;
const levelZeroMaxError =
TerrainProvider.getEstimatedLevelZeroGeometricErrorForAHeightmap(
ellipsoid,
this._width,
tilingScheme.getNumberOfXTilesAtLevel(0),
);
const thisLevelMaxError = levelZeroMaxError / (1 << level);
this._skirtHeight = Math.min(thisLevelMaxError * 4.0, 1000.0);
const createMeshTaskProcessor = throttle
? createMeshTaskProcessorThrottle
: createMeshTaskProcessorNoThrottle;
const verticesPromise = createMeshTaskProcessor.scheduleTask({
heightmap: this._buffer,
structure: structure,
includeWebMercatorT: true,
width: this._width,
height: this._height,
nativeRectangle: nativeRectangle,
rectangle: rectangle,
relativeToCenter: center,
ellipsoid: ellipsoid,
skirtHeight: this._skirtHeight,
isGeographic: tilingScheme.projection instanceof GeographicProjection,
exaggeration: exaggeration,
exaggerationRelativeHeight: exaggerationRelativeHeight,
encoding: this._encoding,
});
if (!defined(verticesPromise)) {
// Postponed
return undefined;
}
const that = this;
return Promise.resolve(verticesPromise).then(function (result) {
let indicesAndEdges;
if (that._skirtHeight > 0.0) {
indicesAndEdges =
TerrainProvider.getRegularGridAndSkirtIndicesAndEdgeIndices(
result.gridWidth,
result.gridHeight,
);
} else E{
indicesAndEdges = TerrainProvider.getRegularGridIndicesAndEdgeIndices(
result.gridWidth,
result.gridHeight,
);
}
const vertexCountWithoutSkirts = result.gridWidth * result.gridHeight;
// Clone complex result objects because the transfer from the web worker
// has stripped them down to JSON-style objects.
that._mesh = new TerrainMesh(
center,
new Float32Array(result.vertices),
indicesAndEdges.indices,
indicesAndEdges.indexCountWithoutSkirts,
vertexCountWithoutSkirts,
result.minimumHeight,
result.maximumHeight,
rectangle,
BoundingSphere.clone(result.boundingSphere3D),
Cartesian3.clone(result.occludeePointInScaledSpace),
result.numberOfAttributes,
OrientedBoundingBox.clone(result.orientedBoundingBox),
TerrainEncoding.clone(result.encoding),
indicesAndEdges.westIndicesSouthToNorth,
indicesAndEdges.southIndicesEastToWest,
indicesAndEdges.eastIndicesNorthToSouth,
indicesAndEdges.northIndicesWestToEast,
);
// Free memory received from server after mesh is created.
that._buffer = undefined;
return that._mesh;
});
};
/**
* @param {object} options Object with the following properties:
* @param {TilingScheme} options.tilingScheme The tiling scheme to which this tile belongs.
* @param {number} options.x The X coordinate of the tile for which to create the terrain data.
* @param {number} options.y The Y coordinate of the tile for which to create the terrain data.
* @param {number} options.level The level of the tile for which to create the terrain data.
* @param {number} [options.exaggeration=1.0] The scale used to exaggerate the terrain.
* @param {number} [options.exaggerationRelativeHeight=0.0] The height relative to which terrain is exaggerated.
*
* @private
*/
HeightmapTerrainData.prototype._createMeshSync = function (options) {
//>>includeStart('debug', pragmas.debug);
Check.typeOf.object("options.tilingScheme", options.tilingScheme);
Check.typeOf.number("options.x", options.x);
Check.typeOf.number("options.y", options.y);
Check.typeOf.number("options.level", options.level);
//>>includeEnd('debug');
const tilingScheme = options.tilingScheme;
const x = options.x;
const y = options.y;
const level = options.level;
const exaggeration = options.exaggeration ?? 1.0;
const exaggerationRelativeHeight = options.exaggerationRelativeHeight ?? 0.0;
const ellipsoid = tilingScheme.ellipsoid;
const nativeRectangle = tilingScheme.tileXYToNativeRectangle(x, y, level);
const rectangle = tilingScheme.tileXYToRectangle(x, y, level);
// Compute the center of the tile for RTC rendering.
const center = ellipsoid.cartographicToCartesian(Rectangle.center(rectangle));
const structure = this._structure;
const levelZeroMaxError =
TerrainProvider.getEstimatedLevelZeroGeometricErrorForAHeightmap(
ellipsoid,
this._width,
tilingScheme.getNumberOfXTilesAtLevel(0),
);
const thisLevelMaxError = levelZeroMaxError / (1 << level);
this._skirtHeight = Math.min(thisLevelMaxError * 4.0, 1000.0);
const result = HeightmapTessellator.computeVertices({
heightmap: this._buffer,
structure: structure,
includeWebMercatorT: true,
width: this._width,
height: this._height,
nativeRectangle: nativeRectangle,
rectangle: rectangle,
relativeToCenter: center,
ellipsoid: ellipsoid,
skirtHeight: this._skirtHeight,
isGeographic: tilingScheme.projection instanceof GeographicProjection,
exaggeration: exaggeration,
exaggerationRelativeHeight: exaggerationRelativeHeight,
});
// Free memory received from server after mesh is created.
this._buffer = undefined;
let indicesAndEdges;
if (this._skirtHeight > 0.0) {
indicesAndEdges =
TerrainProvider.getRegularGridAndSkirtIndicesAndEdgeIndices(
this._width,
this._height,
);
} else E{
indicesAndEdges = TerrainProvider.getRegularGridIndicesAndEdgeIndices(
this._width,
this._height,
);
}
const vertexCountWithoutSkirts = result.gridWidth * result.gridHeight;
// No need to clone here (as we do in the async version) because the result
// is not coming from a web worker.
this._mesh = new TerrainMesh(
center,
result.vertices,
indicesAndEdges.indices,
indicesAndEdges.indexCountWithoutSkirts,
vertexCountWithoutSkirts,
result.minimumHeight,
result.maximumHeight,
rectangle,
result.boundingSphere3D,
result.occludeePointInScaledSpace,
result.encoding.stride,
result.orientedBoundingBox,
result.encoding,
indicesAndEdges.westIndicesSouthToNorth,
indicesAndEdges.southIndicesEastToWest,
indicesAndEdges.eastIndicesNorthToSouth,
indicesAndEdges.northIndicesWestToEast,
);
return this._mesh;
};
/**
* Computes the terrain height at a specified longitude and latitude.
*
* @param {Rectangle} rectangle The rectangle covered by this terrain data.
* @param {number} longitude The longitude in radians.
* @param {number} latitude The latitude in radians.
* @returns {number} The terrain height at the specified position. If the position
* is outside the rectangle, this method will extrapolate the height, which is likely to be wildly
* incorrect for positions far outside the rectangle.
*/
HeightmapTerrainData.prototype.interpolateHeight = function (
rectangle,
longitude,
latitude,
) {
const width = this._width;
const height = this._height;
const structure = this._structure;
const stride = structure.stride;
const elementsPerHeight = structure.elementsPerHeight;
const elementMultiplier = structure.elementMultiplier;
const isBigEndian = structure.isBigEndian;
const heightOffset = structure.heightOffset;
const heightScale = structure.heightScale;
const isMeshCreated = defined(this._mesh);
const isLERCEncoding = this._encoding === HeightmapEncoding.LERC;
const isInterpolationImpossible = !isMeshCreated && isLERCEncoding;
if (isInterpolationImpossible) {
// We can't interpolate using the buffer because it's LERC encoded
// so please call createMesh() first and interpolate using the mesh;
// as mesh creation will decode the LERC buffer
return undefined;
}
let heightSample;
if (isMeshCreated) {
const buffer = this._mesh.vertices;
const encoding = this._mesh.encoding;
heightSample = interpolateMeshHeight(
buffer,
encoding,
heightOffset,
heightScale,
rectangle,
width,
height,
longitude,
latitude,
);
} else {
heightSample = interpolateHeight(
this._buffer,
elementsPerHeight,
elementMultiplier,
stride,
isBigEndian,
rectangle,
width,
height,
longitude,
latitude,
);
heightSample = heightSample * heightScale + heightOffset;
}
return heightSample;
};
/**
* Upsamples this terrain data for use by a descendant tile. The resulting instance will contain a subset of the
* height samples in this instance, interpolated if necessary.
*
* @param {TilingScheme} tilingScheme The tiling scheme of this terrain data.
* @param {number} thisX The X coordinate of this tile in the tiling scheme.
* @param {number} thisY The Y coordinate of this tile in the tiling scheme.
* @param {number} thisLevel The level of this tile in the tiling scheme.
* @param {number} descendantX The X coordinate within the tiling scheme of the descendant tile for which we are upsampling.
* @param {number} descendantY The Y coordinate within the tiling scheme of the descendant tile for which we are upsampling.
* @param {number} descendantLevel The level within the tiling scheme of the descendant tile for which we are upsampling.
* @returns {Promise<HeightmapTerrainData>|undefined} A promise for upsampled heightmap terrain data for the descendant tile,
* or undefined if the mesh is unavailable.
*/
HeightmapTerrainData.prototype.upsample = function (
tilingScheme,
thisX,
thisY,
thisLevel,
descendantX,
descendantY,
descendantLevel,
) {
//>>includeStart('debug', pragmas.debug);
if (!defined(tilingScheme)) {
throw new DeveloperError("tilingScheme is required.");
}
if (!defined(thisX)) {
throw new DeveloperError("thisX is required.");
}
if (!defined(thisY)) {
throw new DeveloperError("thisY is required.");
}
if (!defined(thisLevel)) {
throw new DeveloperError("thisLevel is required.");
}
if (!defined(descendantX)) {
throw new DeveloperError("descendantX is required.");
}
if (!defined(descendantY)) {
throw new DeveloperError("descendantY is required.");
}
if (!defined(descendantLevel)) {
throw new DeveloperError("descendantLevel is required.");
}
const levelDifference = descendantLevel - thisLevel;
if (levelDifference > 1) {
throw new DeveloperError(
"Upsampling through more than one level at a time is not currently supported.",
);
}
//>>includeEnd('debug');
const meshData = this._mesh;
if (!defined(meshData)) {
return undefined;
}
const width = this._width;
const height = this._height;
const structure = this._structure;
const stride = structure.stride;
const heights = new this._bufferType(width * height * stride);
const buffer = meshData.vertices;
const encoding = meshData.encoding;
// PERFORMANCE_IDEA: don't recompute these rectangles - the caller already knows them.
const sourceRectangle = tilingScheme.tileXYToRectangle(
thisX,
thisY,
thisLevel,
);
const destinationRectangle = tilingScheme.tileXYToRectangle(
descendantX,
descendantY,
descendantLevel,
);
const heightOffset = structure.heightOffset;
const heightScale = structure.heightScale;
const elementsPerHeight = structure.elementsPerHeight;
const elementMultiplier = structure.elementMultiplier;
const isBigEndian = structure.isBigEndian;
const divisor = Math.pow(elementMultiplier, elementsPerHeight - 1);
for (let j = 0; j < height; ++j) {
const latitude = CesiumMath.lerp(
destinationRectangle.north,
destinationRectangle.south,
j / (height - 1),
);
for (let i = 0; i < width; ++i) {
const longitude = CesiumMath.lerp(
destinationRectangle.west,
destinationRectangle.east,
i / (width - 1),
);
let heightSample = interpolateMeshHeight(
buffer,
encoding,
heightOffset,
heightScale,
sourceRectangle,
width,
height,
longitude,
latitude,
);
// Use conditionals here instead of Math.min and Math.max so that an undefined
// lowestEncodedHeight or highestEncodedHeight has no effect.
heightSample =
heightSample < structure.lowestEncodedHeight
? structure.lowestEncodedHeight
: heightSample;
heightSample =
heightSample > structure.highestEncodedHeight
? structure.highestEncodedHeight
: heightSample;
setHeight(
heights,
elementsPerHeight,
elementMultiplier,
divisor,
stride,
isBigEndian,
j * width + i,
heightSample,
);
}
}
return Promise.resolve(
new HeightmapTerrainData({
buffer: heights,
width: width,
height: height,
childTileMask: 0,
structure: this._structure,
createdByUpsampling: true,
}),
);
};
/**
* Determines if a given child tile is available, based on the
* {@link HeightmapTerrainData.childTileMask}. The given child tile coordinates are assumed
* to be one of the four children of this tile. If non-child tile coordinates are
* given, the availability of the southeast child tile is returned.
*
* @param {number} thisX The tile X coordinate of this (the parent) tile.
* @param {number} thisY The tile Y coordinate of this (the parent) tile.
* @param {number} childX The tile X coordinate of the child tile to check for availability.
* @param {number} childY The tile Y coordinate of the child tile to check for availability.
* @returns {boolean} True if the child tile is available; otherwise, false.
*/
HeightmapTerrainData.prototype.isChildAvailable = function (
thisX,
thisY,
childX,
childY,
) {
//>>includeStart('debug', pragmas.debug);
Check.typeOf.number("thisX", thisX);
Check.typeOf.number("thisY", thisY);
Check.typeOf.number("childX", childX);
Check.typeOf.number("childY", childY);
//>>includeEnd('debug');
let bitNumber = 2; // northwest child
if (childX !== thisX * 2) {
++bitNumber; // east child
}
if (childY !== thisY * 2) {
bitNumber -= 2; // south child
}
return (this._childTileMask & (1 << bitNumber)) !== 0;
};
/**
* Gets a value indicating whether or not this terrain data was created by upsampling lower resolution
* terrain data. If this value is false, the data was obtained from some other source, such
* as by downloading it from a remote server. This method should return true for instances
* returned from a call to {@link HeightmapTerrainData#upsample}.
*
* @returns {boolean} True if this instance was created by upsampling; otherwise, false.
*/
HeightmapTerrainData.prototype.wasCreatedByUpsampling = function () {
return this._createdByUpsampling;
};
function interpolateHeight(
sourceHeights,
elementsPerHeight,
elementMultiplier,
stride,
isBigEndian,
sourceRectangle,
width,
height,
longitude,
latitude,
) {
const fromWest =
((longitude - sourceRectangle.west) * (width - 1)) /
(sourceRectangle.east - sourceRectangle.west);
const fromSouth =
((latitude - sourceRectangle.south) * (height - 1)) /
(sourceRectangle.north - sourceRectangle.south);
let westInteger = fromWest | 0;
let eastInteger = westInteger + 1;
Iif (eastInteger >= width) {
eastInteger = width - 1;
westInteger = width - 2;
}
let southInteger = fromSouth | 0;
let northInteger = southInteger + 1;
Iif (northInteger >= height) {
northInteger = height - 1;
southInteger = height - 2;
}
const dx = fromWest - westInteger;
const dy = fromSouth - southInteger;
southInteger = height - 1 - southInteger;
northInteger = height - 1 - northInteger;
const southwestHeight = getHeight(
sourceHeights,
elementsPerHeight,
elementMultiplier,
stride,
isBigEndian,
southInteger * width + westInteger,
);
const southeastHeight = getHeight(
sourceHeights,
elementsPerHeight,
elementMultiplier,
stride,
isBigEndian,
southInteger * width + eastInteger,
);
const northwestHeight = getHeight(
sourceHeights,
elementsPerHeight,
elementMultiplier,
stride,
isBigEndian,
northInteger * width + westInteger,
);
const northeastHeight = getHeight(
sourceHeights,
elementsPerHeight,
elementMultiplier,
stride,
isBigEndian,
northInteger * width + eastInteger,
);
return triangleInterpolateHeight(
dx,
dy,
southwestHeight,
southeastHeight,
northwestHeight,
northeastHeight,
);
}
function interpolateMeshHeight(
buffer,
encoding,
heightOffset,
heightScale,
sourceRectangle,
width,
height,
longitude,
latitude,
) {
// returns a height encoded according to the structure's heightScale and heightOffset.
const fromWest =
((longitude - sourceRectangle.west) * (width - 1)) /
(sourceRectangle.east - sourceRectangle.west);
const fromSouth =
((latitude - sourceRectangle.south) * (height - 1)) /
(sourceRectangle.north - sourceRectangle.south);
let westInteger = fromWest | 0;
let eastInteger = westInteger + 1;
if (eastInteger >= width) {
eastInteger = width - 1;
westInteger = width - 2;
}
let southInteger = fromSouth | 0;
let northInteger = southInteger + 1;
if (northInteger >= height) {
northInteger = height - 1;
southInteger = height - 2;
}
const dx = fromWest - westInteger;
const dy = fromSouth - southInteger;
southInteger = height - 1 - southInteger;
northInteger = height - 1 - northInteger;
const southwestHeight =
(encoding.decodeHeight(buffer, southInteger * width + westInteger) -
heightOffset) /
heightScale;
const southeastHeight =
(encoding.decodeHeight(buffer, southInteger * width + eastInteger) -
heightOffset) /
heightScale;
const northwestHeight =
(encoding.decodeHeight(buffer, northInteger * width + westInteger) -
heightOffset) /
heightScale;
const northeastHeight =
(encoding.decodeHeight(buffer, northInteger * width + eastInteger) -
heightOffset) /
heightScale;
return triangleInterpolateHeight(
dx,
dy,
southwestHeight,
southeastHeight,
northwestHeight,
northeastHeight,
);
}
function triangleInterpolateHeight(
dX,
dY,
southwestHeight,
southeastHeight,
northwestHeight,
northeastHeight,
) {
// The HeightmapTessellator bisects the quad from southwest to northeast.
if (dY < dX) {
// Lower right triangle
return (
southwestHeight +
dX * (southeastHeight - southwestHeight) +
dY * (northeastHeight - southeastHeight)
);
}
// Upper left triangle
return (
southwestHeight +
dX * (northeastHeight - northwestHeight) +
dY * (northwestHeight - southwestHeight)
);
}
function getHeight(
heights,
elementsPerHeight,
elementMultiplier,
stride,
isBigEndian,
index,
) {
index *= stride;
let height = 0;
let i;
Iif (isBigEndian) {
for (i = 0; i < elementsPerHeight; ++i) {
height = height * elementMultiplier + heights[index + i];
}
} else {
for (i = elementsPerHeight - 1; i >= 0; --i) {
height = height * elementMultiplier + heights[index + i];
}
}
return height;
}
function setHeight(
heights,
elementsPerHeight,
elementMultiplier,
divisor,
stride,
isBigEndian,
index,
height,
) {
index *= stride;
let i;
if (isBigEndian) {
for (i = 0; i < elementsPerHeight - 1; ++i) {
heights[index + i] = (height / divisor) | 0;
height -= heights[index + i] * divisor;
divisor /= elementMultiplier;
}
} else {
for (i = elementsPerHeight - 1; i > 0; --i) {
heights[index + i] = (height / divisor) | 0;
height -= heights[index + i] * divisor;
divisor /= elementMultiplier;
}
}
heights[index + i] = height;
}
export default HeightmapTerrainData;
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