cesium
Version:
CesiumJS is a JavaScript library for creating 3D globes and 2D maps in a web browser without a plugin.
161 lines (147 loc) • 6.5 kB
JavaScript
import defined from './defined.js';
import DeveloperError from './DeveloperError.js';
import CesiumMath from './Math.js';
import WebGLConstants from './WebGLConstants.js';
/**
* Constants for WebGL index datatypes. These corresponds to the
* <code>type</code> parameter of {@link http://www.khronos.org/opengles/sdk/docs/man/xhtml/glDrawElements.xml|drawElements}.
*
* @exports IndexDatatype
*/
var IndexDatatype = {
/**
* 8-bit unsigned byte corresponding to <code>UNSIGNED_BYTE</code> and the type
* of an element in <code>Uint8Array</code>.
*
* @type {Number}
* @constant
*/
UNSIGNED_BYTE : WebGLConstants.UNSIGNED_BYTE,
/**
* 16-bit unsigned short corresponding to <code>UNSIGNED_SHORT</code> and the type
* of an element in <code>Uint16Array</code>.
*
* @type {Number}
* @constant
*/
UNSIGNED_SHORT : WebGLConstants.UNSIGNED_SHORT,
/**
* 32-bit unsigned int corresponding to <code>UNSIGNED_INT</code> and the type
* of an element in <code>Uint32Array</code>.
*
* @type {Number}
* @constant
*/
UNSIGNED_INT : WebGLConstants.UNSIGNED_INT
};
/**
* Returns the size, in bytes, of the corresponding datatype.
*
* @param {IndexDatatype} indexDatatype The index datatype to get the size of.
* @returns {Number} The size in bytes.
*
* @example
* // Returns 2
* var size = Cesium.IndexDatatype.getSizeInBytes(Cesium.IndexDatatype.UNSIGNED_SHORT);
*/
IndexDatatype.getSizeInBytes = function(indexDatatype) {
switch(indexDatatype) {
case IndexDatatype.UNSIGNED_BYTE:
return Uint8Array.BYTES_PER_ELEMENT;
case IndexDatatype.UNSIGNED_SHORT:
return Uint16Array.BYTES_PER_ELEMENT;
case IndexDatatype.UNSIGNED_INT:
return Uint32Array.BYTES_PER_ELEMENT;
}
//>>includeStart('debug', pragmas.debug);
throw new DeveloperError('indexDatatype is required and must be a valid IndexDatatype constant.');
//>>includeEnd('debug');
};
/**
* Gets the datatype with a given size in bytes.
*
* @param {Number} sizeInBytes The size of a single index in bytes.
* @returns {IndexDatatype} The index datatype with the given size.
*/
IndexDatatype.fromSizeInBytes = function(sizeInBytes) {
switch (sizeInBytes) {
case 2:
return IndexDatatype.UNSIGNED_SHORT;
case 4:
return IndexDatatype.UNSIGNED_INT;
case 1:
return IndexDatatype.UNSIGNED_BYTE;
//>>includeStart('debug', pragmas.debug);
default:
throw new DeveloperError('Size in bytes cannot be mapped to an IndexDatatype');
//>>includeEnd('debug');
}
};
/**
* Validates that the provided index datatype is a valid {@link IndexDatatype}.
*
* @param {IndexDatatype} indexDatatype The index datatype to validate.
* @returns {Boolean} <code>true</code> if the provided index datatype is a valid value; otherwise, <code>false</code>.
*
* @example
* if (!Cesium.IndexDatatype.validate(indexDatatype)) {
* throw new Cesium.DeveloperError('indexDatatype must be a valid value.');
* }
*/
IndexDatatype.validate = function(indexDatatype) {
return defined(indexDatatype) &&
(indexDatatype === IndexDatatype.UNSIGNED_BYTE ||
indexDatatype === IndexDatatype.UNSIGNED_SHORT ||
indexDatatype === IndexDatatype.UNSIGNED_INT);
};
/**
* Creates a typed array that will store indices, using either <code><Uint16Array</code>
* or <code>Uint32Array</code> depending on the number of vertices.
*
* @param {Number} numberOfVertices Number of vertices that the indices will reference.
* @param {Number|Array} indicesLengthOrArray Passed through to the typed array constructor.
* @returns {Uint16Array|Uint32Array} A <code>Uint16Array</code> or <code>Uint32Array</code> constructed with <code>indicesLengthOrArray</code>.
*
* @example
* this.indices = Cesium.IndexDatatype.createTypedArray(positions.length / 3, numberOfIndices);
*/
IndexDatatype.createTypedArray = function(numberOfVertices, indicesLengthOrArray) {
//>>includeStart('debug', pragmas.debug);
if (!defined(numberOfVertices)) {
throw new DeveloperError('numberOfVertices is required.');
}
//>>includeEnd('debug');
if (numberOfVertices >= CesiumMath.SIXTY_FOUR_KILOBYTES) {
return new Uint32Array(indicesLengthOrArray);
}
return new Uint16Array(indicesLengthOrArray);
};
/**
* Creates a typed array from a source array buffer. The resulting typed array will store indices, using either <code><Uint16Array</code>
* or <code>Uint32Array</code> depending on the number of vertices.
*
* @param {Number} numberOfVertices Number of vertices that the indices will reference.
* @param {ArrayBuffer} sourceArray Passed through to the typed array constructor.
* @param {Number} byteOffset Passed through to the typed array constructor.
* @param {Number} length Passed through to the typed array constructor.
* @returns {Uint16Array|Uint32Array} A <code>Uint16Array</code> or <code>Uint32Array</code> constructed with <code>sourceArray</code>, <code>byteOffset</code>, and <code>length</code>.
*
*/
IndexDatatype.createTypedArrayFromArrayBuffer = function(numberOfVertices, sourceArray, byteOffset, length) {
//>>includeStart('debug', pragmas.debug);
if (!defined(numberOfVertices)) {
throw new DeveloperError('numberOfVertices is required.');
}
if (!defined(sourceArray)) {
throw new DeveloperError('sourceArray is required.');
}
if (!defined(byteOffset)) {
throw new DeveloperError('byteOffset is required.');
}
//>>includeEnd('debug');
if (numberOfVertices >= CesiumMath.SIXTY_FOUR_KILOBYTES) {
return new Uint32Array(sourceArray, byteOffset, length);
}
return new Uint16Array(sourceArray, byteOffset, length);
};
export default Object.freeze(IndexDatatype);