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The Tor Browser
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use-program-crash-with-discard-in-fragment-shader.html (2285B)

      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>WebGL Program Conformance Tests</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" width="2" height="2"> </canvas>
     20 <script id="vertexShader" language="x-shader/x-vertex">
     21 attribute vec4 ATTR0;
     22 void main()
     23 {
     24  gl_Position = ATTR0;
     25 }
     26 </script>
     27 <script id="fragmentShader" language="x-shader/x-fragment">
     28 precision mediump float;
     29 void main()
     30 {
     31  float _Intensity = exp2(gl_FragCoord.w);
     32  if (_Intensity < 0.5) {
     33    discard;
     34  }
     35  gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0);
     36 }
     37 </script>
     38 <script>
     39 "use strict";
     40 description('Regression test for crash in Mac OS AMD OpenGL driver related to use of discard in fragment shader.<br><br>More specifically, triggering the crash seems to require examination of gl_FragCoord.w, use of exp2, and a call to discard in the fragment shader. Thanks to Sheheryar Zakaria and Michael Braithwaite at Turbulenz for the original test case.<br><a href="https://bugs.webkit.org/show_bug.cgi?id=73932">WebKit bug 73932</a><br>');
     41 
     42 debug("");
     43 
     44 var wtu = WebGLTestUtils;
     45 var gl = wtu.create3DContext("canvas");
     46 if (!gl) {
     47  testFailed("context does not exist");
     48 } else {
     49  testPassed("context exists");
     50 }
     51 
     52 debug("");
     53 
     54 var program = wtu.loadProgramFromScript(gl, 'vertexShader', 'fragmentShader');
     55 if (program) {
     56  testPassed("Program linked successfully");
     57 } else {
     58  testFailed("Program failed to link");
     59 }
     60 
     61 // Crash occurs here on affected machines
     62 gl.useProgram(program);
     63 
     64 // In some browsers, such as Chrome, the above crash only causes a
     65 // lost context event to be dispatched, and not synchronously. To verify
     66 // that everything worked, clear and read back the frame buffer.
     67 gl.clearColor(1.0, 0.0, 0.0, 1.0);
     68 gl.clear(gl.COLOR_BUFFER_BIT);
     69 wtu.checkCanvasRect(gl, 0, 0, 1, 1, [255, 0, 0, 255],
     70    "Color should be red");
     71 
     72 var successfullyParsed = true;
     73 </script>
     74 <script src="../../js/js-test-post.js"></script>
     75 
     76 </body>
     77 </html>