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133 lines
2.8 KiB
133 lines
2.8 KiB
/**
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* @module ol/webgl
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*/
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import {SAFARI_BUG_237906} from './has.js';
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/**
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* Constants taken from goog.webgl
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*/
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/**
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* Used by {@link module:ol/webgl/Helper~WebGLHelper} for buffers containing vertices data, such as
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* position, color, texture coordinate, etc. These vertices are then referenced by an index buffer
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* to be drawn on screen (see {@link module:ol/webgl.ELEMENT_ARRAY_BUFFER}).
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* @const
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* @type {number}
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* @api
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*/
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export const ARRAY_BUFFER = 0x8892;
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/**
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* Used by {@link module:ol/webgl/Helper~WebGLHelper} for buffers containing indices data.
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* Index buffers are essentially lists of references to vertices defined in a vertex buffer
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* (see {@link module:ol/webgl.ARRAY_BUFFER}), and define the primitives (triangles) to be drawn.
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* @const
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* @type {number}
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* @api
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*/
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export const ELEMENT_ARRAY_BUFFER = 0x8893;
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/**
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* Used by {link module:ol/webgl/Buffer~WebGLArrayBuffer}.
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* @const
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* @type {number}
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* @api
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*/
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export const STREAM_DRAW = 0x88e0;
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/**
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* Used by {link module:ol/webgl/Buffer~WebGLArrayBuffer}.
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* @const
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* @type {number}
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* @api
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*/
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export const STATIC_DRAW = 0x88e4;
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/**
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* Used by {link module:ol/webgl/Buffer~WebGLArrayBuffer}.
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* @const
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* @type {number}
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* @api
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*/
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export const DYNAMIC_DRAW = 0x88e8;
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/**
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* @const
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* @type {number}
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*/
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export const UNSIGNED_BYTE = 0x1401;
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/**
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* @const
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* @type {number}
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*/
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export const UNSIGNED_SHORT = 0x1403;
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/**
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* @const
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* @type {number}
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*/
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export const UNSIGNED_INT = 0x1405;
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/**
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* @const
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* @type {number}
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*/
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export const FLOAT = 0x1406;
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/** end of goog.webgl constants
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*/
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/**
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* @const
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* @type {Array<string>}
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*/
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const CONTEXT_IDS = ['experimental-webgl', 'webgl', 'webkit-3d', 'moz-webgl'];
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/**
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* @param {HTMLCanvasElement} canvas Canvas.
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* @param {Object} [attributes] Attributes.
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* @return {WebGLRenderingContext} WebGL rendering context.
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*/
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export function getContext(canvas, attributes) {
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attributes = Object.assign(
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{
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preserveDrawingBuffer: true,
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antialias: SAFARI_BUG_237906 ? false : true, // https://bugs.webkit.org/show_bug.cgi?id=237906
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},
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attributes
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);
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const ii = CONTEXT_IDS.length;
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for (let i = 0; i < ii; ++i) {
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try {
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const context = canvas.getContext(CONTEXT_IDS[i], attributes);
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if (context) {
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return /** @type {!WebGLRenderingContext} */ (context);
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}
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} catch (e) {
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// pass
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}
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}
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return null;
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}
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/**
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* @type {Array<string>}
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*/
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let supportedExtensions;
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/**
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* @return {Array<string>} List of supported WebGL extensions.
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*/
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export function getSupportedExtensions() {
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if (!supportedExtensions) {
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const canvas = document.createElement('canvas');
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const gl = getContext(canvas);
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if (gl) {
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supportedExtensions = gl.getSupportedExtensions();
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}
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}
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return supportedExtensions;
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}
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