112 lines
4.5 KiB
JavaScript
112 lines
4.5 KiB
JavaScript
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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(function(){
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"use strict";
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const logging = require("./logging");
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let scope;
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if ((typeof exports) !== "undefined"){
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scope = exports;
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}
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else {
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scope = require.register("./webgl", {});
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}
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scope.copyCanvasToWebgl = function copyCanvasToWebgl(window, canvas, webGLVersion = "webgl"){
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const webGlCanvas = canvas.cloneNode(true);
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const context =
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window.HTMLCanvasElement.prototype.getContext.call(webGlCanvas, webGLVersion) ||
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window.HTMLCanvasElement.prototype.getContext.call(webGlCanvas, "experimental-" + webGLVersion);
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if (!context){
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// unable to get a context...
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logging.warning("unable to create webgl context.");
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return {canvas: false, context: false};
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}
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context.viewport(0, 0, webGlCanvas.width, webGlCanvas.height);
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const program = context.createProgram();
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const vertexShader = context.createShader(context.VERTEX_SHADER);
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const vertex = "attribute vec4 a_position;\nattribute vec2 a_texCoord;\nvarying vec2 v_texCoord;\n" +
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"void main(){\n\tgl_Position = a_position;\n\tv_texCoord = a_texCoord;\n}";
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context.shaderSource(vertexShader, vertex);
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context.compileShader(vertexShader);
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if (!context.getShaderParameter(vertexShader, context.COMPILE_STATUS)){
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context.deleteShader(vertexShader);
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logging.warning("webgl: failed to compile vertex shader.");
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return {canvas: false, context: false};
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}
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context.attachShader(program, vertexShader);
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const fragmentShader = context.createShader(context.FRAGMENT_SHADER);
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const fragmenter = "precision mediump float;\nuniform sampler2D u_image;\nvarying vec2 v_texCoord;\n" +
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"void main(){\n\tgl_FragColor = texture2D(u_image, v_texCoord);\n}";
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context.shaderSource(fragmentShader, fragmenter);
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context.compileShader(fragmentShader);
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if (!context.getShaderParameter(fragmentShader, context.COMPILE_STATUS)){
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context.deleteShader(fragmentShader);
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logging.warning("webgl: failed to compile fragmenter shader.");
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return {canvas: false, context: false};
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}
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context.attachShader(program, fragmentShader);
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context.linkProgram(program);
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if (!context.getProgramParameter(program, context.LINK_STATUS)){
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context.deleteProgram(program);
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logging.warning("webgl: failed to link program.");
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return {canvas: false, context: false};
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}
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context.useProgram(program);
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const positionBuffer = context.createBuffer();
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context.bindBuffer(context.ARRAY_BUFFER, positionBuffer);
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context.bufferData(context.ARRAY_BUFFER, new Float32Array([
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-1, -1,
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-1, 1,
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1, -1,
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1, 1,
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-1, 1,
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1, -1
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]), context.STATIC_DRAW);
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const positionAttributeLocation = context.getAttribLocation(program, "a_position");
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context.enableVertexAttribArray(positionAttributeLocation);
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const size = 2; // 2 components per iteration
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const type = context.FLOAT; // the data is 32bit floats
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const normalize = false; // don't normalize the data
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const stride = 0; // 0 = move forward size * sizeof(type) each iteration to get the next position
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const offset = 0; // start at the beginning of the buffer
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context.vertexAttribPointer(positionAttributeLocation, size, type, normalize, stride, offset);
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const texCoordLocation = context.getAttribLocation(program, "a_texCoord");
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// provide texture coordinates for the rectangle.
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const texCoordBuffer = context.createBuffer();
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context.bindBuffer(context.ARRAY_BUFFER, texCoordBuffer);
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context.bufferData(context.ARRAY_BUFFER, new Float32Array([
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0, 1,
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0, 0,
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1, 1,
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1, 0,
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0, 0,
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1, 1
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]), context.STATIC_DRAW);
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context.enableVertexAttribArray(texCoordLocation);
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context.vertexAttribPointer(texCoordLocation, 2, context.FLOAT, false, 0, 0);
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context.bindTexture(context.TEXTURE_2D, context.createTexture());
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context.texParameteri(context.TEXTURE_2D, context.TEXTURE_WRAP_S, context.CLAMP_TO_EDGE);
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context.texParameteri(context.TEXTURE_2D, context.TEXTURE_WRAP_T, context.CLAMP_TO_EDGE);
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context.texParameteri(context.TEXTURE_2D, context.TEXTURE_MIN_FILTER, context.NEAREST);
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context.texParameteri(context.TEXTURE_2D, context.TEXTURE_MAG_FILTER, context.NEAREST);
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context.texImage2D(context.TEXTURE_2D, 0, context.RGBA, context.RGBA, context.UNSIGNED_BYTE, canvas);
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context.drawArrays(context.TRIANGLES /*primitiveType*/, 0 /*triangleOffset*/, 6 /*count*/);
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return {webGlCanvas, context};
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};
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}()); |