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node_modules/ol/src/webgl.js

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+/**
+ * @module ol/webgl
+ */
+
+import {SAFARI_BUG_237906} from './has.js';
+import {assign} from './obj.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} [opt_attributes] Attributes.
+ * @return {WebGLRenderingContext} WebGL rendering context.
+ */
+export function getContext(canvas, opt_attributes) {
+  const attributes = assign(
+    {
+      preserveDrawingBuffer: true,
+      antialias: SAFARI_BUG_237906 ? false : true, // https://bugs.webkit.org/show_bug.cgi?id=237906
+    },
+    opt_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;
+}