dom/canvas/test/webgl-conf/checkout/conformance/glsl/variables/gl-frontfacing.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>gl-fragcoord Test</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 <canvas id="example" width="32" height="32">
  18 </canvas>
  19 <div id="description"></div>
  20 <div id="console"></div>
  21 <script id="vshader" type="x-shader/x-vertex">
  22 attribute vec4 vPosition;
  23 void main()
  24 {
  25   gl_Position = vPosition;
  26 }
  27 </script>
  28
  29 <script id="fshader" type="x-shader/x-fragment">
  30 precision mediump float;
  31 void main()
  32 {
  33   gl_FragColor = vec4(
  34       gl_FrontFacing ? 1.0 : 0.0,
  35       gl_FrontFacing ? 0.0 : 1.0,
  36       0,
  37       1);
  38 }
  39 </script>
  40
  41 <script>
  42 "use strict";
  43 function init()
  44 {
  45   description("tests gl_FrontFacing");
  46
  47   var wtu = WebGLTestUtils;
  48   var gl = wtu.create3DContext("example");
  49   var program = wtu.setupProgram(gl, ["vshader", "fshader"], ["vPosition"]);
  50
  51   var gridRes = 4;
  52   wtu.setupIndexedQuad(gl, gridRes, 0, true);
  53
  54   gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
  55   gl.drawElements(gl.TRIANGLES, gridRes * gridRes * 6, gl.UNSIGNED_SHORT, 0);
  56   wtu.glErrorShouldBe(gl, gl.NO_ERROR, "no errors from draw");
  57
  58   var step = 32 / gridRes;
  59   var halfStep = step / 2;
  60   var quarterStep = halfStep / 2;
  61   for (var xx = 0; xx < 32; xx += step) {
  62     for (var yy = 0; yy < 32; yy += step) {
  63       for (var ii = 0; ii < 2; ++ii) {
  64         var color = [
  65             ii == 0 ? 255 : 0,
  66             ii == 0 ? 0 : 255,
  67             0
  68         ];
  69         var msg = "should be " + color;
  70         wtu.checkCanvasRect(
  71             gl,
  72             xx + quarterStep + halfStep * ii,
  73             yy + quarterStep + halfStep * ii,
  74             1, 1, color, msg, 4);
  75       }
  76     }
  77   }
  78 }
  79
  80 init();
  81 var successfullyParsed = true;
  82 </script>
  83 <script src="../../../js/js-test-post.js"></script>
  84
  85 </body>
  86 </html>