dom/canvas/test/webgl-conf/checkout/conformance/rendering/culling.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 <link rel="stylesheet" href="../../resources/js-test-style.css"/>
  12 <script src="../../js/js-test-pre.js"></script>
  13 <script src="../../js/webgl-test-utils.js"></script>
  14 <script id="vshader" type="x-shader/x-vertex">
  15 attribute vec2 pos;
  16
  17 void main()
  18 {
  19     gl_Position = vec4(pos, 0, 1);
  20 }
  21 </script>
  22
  23 <script id="fshader" type="x-shader/x-fragment">
  24 precision mediump float;
  25 uniform vec4 col;
  26
  27 void main()
  28 {
  29     gl_FragColor = col;
  30 }
  31 </script>
  32
  33 <script>
  34 "use strict";
  35 var wtu = WebGLTestUtils;
  36
  37 function draw(gl, arr, colLoc, col) {
  38     var vertices = new Float32Array(arr);
  39     var vertBuf = gl.createBuffer();
  40     gl.bindBuffer(gl.ARRAY_BUFFER, vertBuf);
  41     gl.bufferData(gl.ARRAY_BUFFER, vertices, gl.STATIC_DRAW);
  42     gl.vertexAttribPointer(0, 2, gl.FLOAT, false, 0, 0);
  43     gl.uniform4fv(colLoc, col);
  44     gl.drawArrays(gl.TRIANGLE_STRIP, 0, vertices.length / 2);
  45 }
  46
  47 function clear(gl, col) {
  48     gl.clearColor(col[0], col[1], col[2], col[3]);
  49     gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
  50 }
  51
  52 function check(gl, winding, shoulddraw) {
  53     var msg = winding + ' face was ' + (shoulddraw ? '' : 'not ') + 'drawn.';
  54     wtu.checkCanvasRect(gl, 0, 0, 1, 1, [0, 255, 0, 255], msg);
  55 }
  56
  57 function runTest() {
  58     var cwVertices = [-1, -1, -1, 1, 1, -1, 1, 1];
  59     var ccwVertices = [-1, 1, -1, -1, 1, 1, 1, -1];
  60     var red = [1, 0, 0, 1];
  61     var green = [0, 1, 0, 1];
  62     var ok;
  63
  64     var gl = wtu.create3DContext('testbed', { antialias: false });
  65     if (!gl) {
  66         testFailed('could not create context');
  67         return;
  68     }
  69     var program = wtu.setupProgram(gl, ['vshader', 'fshader'], ['pos']);
  70     var colLoc = gl.getUniformLocation(program, 'col');
  71
  72     gl.enableVertexAttribArray(0);
  73
  74     debug('CULL_FACE should be off by default');
  75     clear(gl, red);
  76     draw(gl, ccwVertices, colLoc, green);
  77     check(gl, 'CCW', true);
  78     clear(gl, red);
  79     draw(gl, cwVertices, colLoc, green);
  80     check(gl, 'CW', true);
  81
  82     debug('Enabling CULL_FACE');
  83     gl.enable(gl.CULL_FACE);
  84
  85     debug('BACK and CCW should be set by default');
  86     clear(gl, red);
  87     draw(gl, ccwVertices, colLoc, green);
  88     check(gl, 'CCW', true);
  89     clear(gl, green);
  90     draw(gl, cwVertices, colLoc, red);
  91     check(gl, 'CW', false);
  92
  93     var tests = [{ cullFace : 'BACK', frontFace : 'CCW', drawCCW : true, drawCW : false},
  94                  { cullFace : 'BACK', frontFace : 'CW', drawCCW : false, drawCW : true},
  95                  { cullFace : 'FRONT', frontFace : 'CCW', drawCCW : false, drawCW : true },
  96                  { cullFace : 'FRONT', frontFace : 'CW', drawCCW : true, drawCW : false},
  97                  { cullFace : 'FRONT_AND_BACK', frontFace : 'CCW', drawCCW : false, drawCW : false},
  98                  { cullFace : 'FRONT_AND_BACK', frontFace : 'CW', drawCCW : false, drawCW : false}];
  99
 100     for (var i = 0; i < tests.length; ++i) {
 101         var t = tests[i];
 102         debug('Setting ' + t.cullFace + ' and ' + t.frontFace);
 103         gl.cullFace(gl[t.cullFace]);
 104         gl.frontFace(gl[t.frontFace]);
 105         clear(gl, t.drawCCW ? red : green);
 106         draw(gl, ccwVertices, colLoc, t.drawCCW ? green : red);
 107         check(gl, 'CCW', t.drawCCW);
 108         clear(gl, t.drawCW ? red : green);
 109         draw(gl, cwVertices, colLoc, t.drawCW ? green : red);
 110         check(gl, 'CW', t.drawCW);
 111     }
 112 }
 113 </script>
 114 </head>
 115 <body>
 116 <canvas id="testbed" width="16" height="16" style="width:50px; height:50px"></canvas>
 117 <div id="description"></div>
 118 <div id="console"></div>
 119 <script>
 120 "use strict";
 121 description('Verify that culling works');
 122 runTest();
 123 var successfullyParsed = true;
 124 </script>
 125 <script src="../../js/js-test-post.js"></script>
 126 </body>
 127 </html>