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