dom/canvas/test/webgl-conf/checkout/conformance/rendering/draw-webgl-to-canvas-2d-repeatedly.html

   1 <!--
   2 Copyright (c) 2019 The Khronos Group Inc.
   3 Use of this source code is governed by an MIT-style license that can be
   4 found in the LICENSE.txt file.
   5 -->
   6
   7 <!DOCTYPE html>
   8 <html>
   9 <head>
  10 <meta charset="utf-8">
  11 <title>Draw WebGL to Canvas2D Repeatedly</title>
  12 <link rel="stylesheet" href="../../resources/js-test-style.css"/>
  13 <script src="../../js/js-test-pre.js"></script>
  14 <script src="../../js/webgl-test-utils.js"></script>
  15 </head>
  16 <body>
  17 <div id="description"></div>
  18 <div id="console"></div>
  19 <canvas id="canvas-webgl" width="256" height="256"></canvas>
  20 <canvas id="canvas-2d" width="256" height="256"></canvas>
  21 <script>
  22 "use strict";
  23 const wtu = WebGLTestUtils;
  24
  25 const sz = 256;
  26
  27 function drawTo2DCanvas(c2, webGLCanvas) {
  28   // Always clear 2D canvas to solid green first.
  29   c2.clearRect(0, 0, sz, sz);
  30   c2.fillStyle = 'rgb(0,255,0)';
  31   c2.fillRect(0, 0, sz, sz);
  32   // Draw WebGL canvas to this canvas.
  33   c2.drawImage(webGLCanvas, 0, 0);
  34 }
  35
  36 function runTest() {
  37   description();
  38   debug('Repeatedly drawing a WebGL canvas to a 2D canvas should only draw the most recently rendered WebGL content.');
  39   debug('Regression test for <a href="http://crbug.com/894021">http://crbug.com/894021</a>');
  40
  41   let c2 = document.getElementById('canvas-2d').getContext('2d');
  42   let webGLCanvas = document.getElementById('canvas-webgl');
  43   let gl = wtu.create3DContext(webGLCanvas, { alpha: true, antialias: false, premultipliedAlpha: true });
  44   let tolerance = 2;
  45
  46   // Clear left half of WebGL canvas to red and right half to
  47   // transparent black.
  48   gl.disable(gl.SCISSOR_TEST);
  49   gl.clearColor(0.0, 0.0, 0.0, 0.0);
  50   gl.clear(gl.COLOR_BUFFER_BIT);
  51   gl.scissor(0, 0, sz / 2, sz);
  52   gl.enable(gl.SCISSOR_TEST);
  53   gl.clearColor(1.0, 0.0, 0.0, 1.0);
  54   gl.clear(gl.COLOR_BUFFER_BIT);
  55   // Draw to 2D canvas.
  56   drawTo2DCanvas(c2, webGLCanvas);
  57
  58   // Clear right half of WebGL canvas to red and left half to
  59   // transparent black.
  60   gl.disable(gl.SCISSOR_TEST);
  61   gl.clearColor(0.0, 0.0, 0.0, 0.0);
  62   gl.clear(gl.COLOR_BUFFER_BIT);
  63   gl.scissor(sz / 2, 0, sz / 2, sz);
  64   gl.enable(gl.SCISSOR_TEST);
  65   gl.clearColor(1.0, 0.0, 0.0, 1.0);
  66   gl.clear(gl.COLOR_BUFFER_BIT);
  67   // Draw to 2D canvas.
  68   drawTo2DCanvas(c2, webGLCanvas);
  69
  70   // Clear WebGL canvas to transparent black.
  71   gl.disable(gl.SCISSOR_TEST);
  72   gl.clearColor(0.0, 0.0, 0.0, 0.0);
  73   gl.clear(gl.COLOR_BUFFER_BIT);
  74   // Draw to 2D canvas.
  75   drawTo2DCanvas(c2, webGLCanvas);
  76
  77   // 2D canvas should be green.
  78   // In the error case, the rendering results from earlier draws were
  79   // being accumulated, so the 2D canvas was ultimately red.
  80   wtu.checkCanvasRect(c2, 0, 0, sz, sz,
  81                       [ 0, 255, 0, 255 ],
  82                       "should be green",
  83                       tolerance);
  84
  85   finishTest();
  86 }
  87
  88 requestAnimationFrame(runTest);
  89 </script>
  90 </body>
  91 </html>