dom/canvas/test/webgl-conf/checkout/conformance/glsl/bugs/conditional-discard-in-loop.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
   8 <!DOCTYPE html>
   9 <html>
  10 <head>
  11 <meta charset="utf-8">
  12 <title>Conditional discard in loop issue</title>
  13 <link rel="stylesheet" href="../../../resources/js-test-style.css"/>
  14 <script src="../../../js/js-test-pre.js"></script>
  15 <script src="../../../js/webgl-test-utils.js"></script>
  16 </head>
  17
  18 <body>
  19 <canvas id="output" style="border: none;" width="256" height="256"></canvas>
  20 <div id="description"></div>
  21 <div id="console"></div>
  22
  23 <script id="shader-vs" type="x-shader/x-vertex">
  24 // Inputs
  25 attribute vec4 a_position;
  26 attribute vec2 a_tex_coords;
  27
  28 // Output
  29 varying vec2   v_tex_coords;
  30
  31 void main(void) {
  32     v_tex_coords = a_tex_coords;
  33     gl_Position  = a_position;
  34 }
  35 </script>
  36
  37 <script id="shader-fs" type="x-shader/x-fragment">
  38 precision mediump float;
  39
  40 // Constants
  41 const float TEXEL_COUNT_V = 256.0;
  42 const float TEXEL_HEIGHT  = 1.0 / TEXEL_COUNT_V;
  43 const float SEP_IX        = TEXEL_COUNT_V / 2.0;
  44
  45 const vec4 GREEN = vec4(0.0, 1.0, 0.0, 1.0);
  46 const vec4 BLUE  = vec4(0.0, 0.0, 1.0, 1.0);
  47
  48 // Input
  49 varying vec2 v_tex_coords;
  50
  51 uniform sampler2D u_data;
  52
  53 // Without this function or directly returning the data, the issue does not occur
  54 mediump vec4 UnpackData(in vec4 inData) {
  55      float s = inData.x;
  56      // Note s is always 0
  57      // mod(0, 1) = 0
  58      // So return value = (0, 0, -1, 0)
  59     return vec4(0.0, 0.0, mod(s, 1.0) - 1.0, 0.0);
  60
  61     // Comment out the line above and uncomment the line below and the test succeeds on angle-dx11
  62     // return vec4(0.0, 0.0, -1.0, 0.0);
  63 }
  64
  65 void main(void) {
  66      // Set initial color
  67     gl_FragColor = BLUE;
  68
  69     if (gl_FragCoord.y <= SEP_IX) {
  70         mediump vec2 addr = vec2(v_tex_coords.x, TEXEL_HEIGHT);
  71
  72         for (float e_ix = 0.0; e_ix < TEXEL_COUNT_V; ++e_ix) {
  73             vec4 entry = texture2D(u_data, addr);
  74             mediump vec4 unpack = UnpackData(entry);
  75
  76             // Buffer is filled with 0, unpack is always (0, 0, -1, 0)
  77             // So discard is always triggered
  78             if (unpack.z == -1.0) {
  79                 discard;
  80             }
  81
  82             addr.y += unpack.z * TEXEL_HEIGHT;
  83         }
  84         // If discard is not triggered the output color is blue
  85     }
  86     else {
  87         gl_FragColor = GREEN;
  88     }
  89 }
  90 </script>
  91
  92
  93 <script>
  94 "use strict";
  95
  96 description();
  97 debug("");
  98 debug("If the code is executed correctly, the upper half of the viewport will be green, the lower half will be red.");
  99 debug("This is a conformance suite test for the issue reported here : https://code.google.com/p/angleproject/issues/detail?id=706");
 100
 101 var wtu = WebGLTestUtils;
 102 var canvas = document.getElementById("output");
 103 var gl = wtu.create3DContext(canvas);
 104 if (!gl) {
 105   testFailed("context does not exist");
 106 } else {
 107
 108   // Create texture filled with zero's
 109   var tex = gl.createTexture();
 110   gl.bindTexture(gl.TEXTURE_2D, tex);
 111   gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S,     gl.CLAMP_TO_EDGE);
 112   gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T,     gl.CLAMP_TO_EDGE);
 113   gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST);
 114   gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST);
 115   wtu.fillTexture(gl, tex, 256, 256, [0, 0, 0, 0]);
 116
 117   // Clear complete viewport to red
 118   gl.clearColor(1.0, 0.0, 0.0, 1.0);
 119   gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
 120
 121   var attribBuffers = wtu.setupUnitQuad(gl, 0, 1);
 122   var program = wtu.setupProgram(gl, ["shader-vs", "shader-fs"], ["a_position", "a_tex_coords"], [0, 1], true);
 123
 124   // Bind texture
 125   var uniformMap = wtu.getUniformMap(gl, program);
 126   gl.activeTexture(gl.TEXTURE0);
 127   gl.bindTexture(gl.TEXTURE_2D, tex);
 128   gl.uniform1i(uniformMap.u_data.location, 0);
 129
 130   // Draw
 131   wtu.drawUnitQuad(gl);
 132
 133   // Verify output
 134   wtu.checkCanvasRect(gl, 0,   0, 256, 128, [ 255,   0,   0, 255 ], "should be red",    1);
 135   wtu.checkCanvasRect(gl, 0, 128, 256, 128, [   0, 255,   0, 255 ], "should be green",  1);
 136 }
 137
 138 var successfullyParsed = true;
 139 </script>
 140 <script src="../../../js/js-test-post.js"></script>
 141 </body>
 142 </html>