Webgl / remove handling of element_index_uint extension

From now on we will assume this extension is always enabled.

An error message have been added in the unlikely scenario of a lack
of support.

src/ol/webgl/Buffer.js

@@ -2,8 +2,7 @@
  * @module ol/webgl/Buffer
  */
 import {STATIC_DRAW, STREAM_DRAW, DYNAMIC_DRAW} from '../webgl.js';
-import {includes} from '../array.js';
-import {ARRAY_BUFFER, ELEMENT_ARRAY_BUFFER, EXTENSIONS as WEBGL_EXTENSIONS} from '../webgl.js';
+import {ARRAY_BUFFER, ELEMENT_ARRAY_BUFFER} from '../webgl.js';
 import {assert} from '../asserts.js';
 
 /**
@@ -44,7 +43,7 @@ class WebGLArrayBuffer {
 
     /**
      * @private
-     * @type {Float32Array|Uint32Array|Uint16Array}
+     * @type {Float32Array|Uint32Array}
      */
     this.array = null;
 
@@ -96,7 +95,7 @@ class WebGLArrayBuffer {
   }
 
   /**
-   * @return {Float32Array|Uint32Array|Uint16Array} Array.
+   * @return {Float32Array|Uint32Array} Array.
    */
   getArray() {
     return this.array;
@@ -113,15 +112,14 @@ class WebGLArrayBuffer {
 /**
  * Returns a typed array constructor based on the given buffer type
  * @param {number} type Buffer type, either ARRAY_BUFFER or ELEMENT_ARRAY_BUFFER.
- * @returns {Float32ArrayConstructor|Uint16ArrayConstructor|Uint32ArrayConstructor} The typed array class to use for this buffer.
+ * @returns {Float32ArrayConstructor|Uint32ArrayConstructor} The typed array class to use for this buffer.
  */
 export function getArrayClassForType(type) {
   switch (type) {
     case ARRAY_BUFFER:
       return Float32Array;
     case ELEMENT_ARRAY_BUFFER:
-      const hasExtension = includes(WEBGL_EXTENSIONS, 'OES_element_index_uint');
-      return hasExtension ? Uint32Array : Uint16Array;
+      return Uint32Array;
     default:
       return Float32Array;
   }

src/ol/webgl/Helper.js

@@ -2,12 +2,10 @@
  * @module ol/webgl/Helper
  */
 import {getUid} from '../util.js';
-import {EXTENSIONS as WEBGL_EXTENSIONS} from '../webgl.js';
 import Disposable from '../Disposable.js';
-import {includes} from '../array.js';
 import {listen, unlistenAll} from '../events.js';
 import {clear} from '../obj.js';
-import {TEXTURE_2D, TEXTURE_WRAP_S, TEXTURE_WRAP_T} from '../webgl.js';
+import {TEXTURE_2D, TEXTURE_WRAP_S, TEXTURE_WRAP_T, EXTENSIONS as WEBGL_EXTENSIONS} from '../webgl.js';
 import ContextEventType from '../webgl/ContextEventType.js';
 import {
   create as createTransform,
@@ -19,6 +17,8 @@ import {
 import {create, fromTransform} from '../vec/mat4.js';
 import WebGLPostProcessingPass from './PostProcessingPass.js';
 import {getContext} from '../webgl.js';
+import {includes} from '../array.js';
+import {assert} from '../asserts.js';
 
 
 /**
@@ -258,16 +258,8 @@ class WebGLHelper extends Disposable {
      */
     this.currentProgram_ = null;
 
-    /**
-     * @type {boolean}
-     * @private
-     */
-    this.hasOESElementIndexUint_ = includes(WEBGL_EXTENSIONS, 'OES_element_index_uint');
-
-    // use the OES_element_index_uint extension if available
-    if (this.hasOESElementIndexUint_) {
-      gl.getExtension('OES_element_index_uint');
-    }
+    assert(includes(WEBGL_EXTENSIONS, 'OES_element_index_uint'), 63);
+    gl.getExtension('OES_element_index_uint');
 
     listen(this.canvas_, ContextEventType.LOST,
       this.handleWebGLContextLost, this);
@@ -453,9 +445,8 @@ class WebGLHelper extends Disposable {
    */
   drawElements(start, end) {
     const gl = this.getGL();
-    const elementType = this.hasOESElementIndexUint_ ?
-      gl.UNSIGNED_INT : gl.UNSIGNED_SHORT;
-    const elementSize = this.hasOESElementIndexUint_ ? 4 : 2;
+    const elementType = gl.UNSIGNED_INT;
+    const elementSize = 4;
 
     const numItems = end - start;
     const offsetInBytes = start * elementSize;
@@ -747,16 +738,6 @@ class WebGLHelper extends Disposable {
   handleWebGLContextRestored() {
   }
 
-  /**
-   * Returns whether the `OES_element_index_uint` WebGL extension is enabled for this context.
-   * @return {boolean} If true, Uint16Array should be used for element array buffers
-   * instead of Uint8Array.
-   * @api
-   */
-  getElementIndexUintEnabled() {
-    return this.hasOESElementIndexUint_;
-  }
-
   // TODO: shutdown program
 
   /**