dom/canvas/test/webgl-conf/checkout/conformance/extensions/webgl-draw-buffers-max-draw-buffers.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>WebGL WEBGL_draw_buffers gl_FragData[gl_MaxDrawBuffers] Conformance 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 <div id="description"></div>
  18 <canvas id="canvas" width="64" height="64"> </canvas>
  19 <div id="console"></div>
  20 <script id="vshader" type="x-shader/x-vertex">
  21 attribute vec4 a_position;
  22 void main() {
  23     gl_Position = a_position;
  24 }
  25 </script>
  26 <script id="fshader" type="x-shader/x-fragment">
  27 #extension GL_EXT_draw_buffers : require
  28 precision mediump float;
  29 void main() {
  30     gl_FragData[gl_MaxDrawBuffers] = vec4(0.0);
  31 }
  32 </script>
  33 <script id="fshaderConstantIndex" type="x-shader/x-fragment">
  34 #extension GL_EXT_draw_buffers : require
  35 precision mediump float;
  36 void main() {
  37     gl_FragData[$(gl_MaxDrawBuffers)] = vec4(0.0);
  38 }
  39 </script>
  40 <script id="fshaderTestMaxDrawBuffersValue" type="x-shader/x-fragment">
  41 #extension GL_EXT_draw_buffers : require
  42 precision mediump float;
  43 void main() {
  44     gl_FragColor = ($(gl_MaxDrawBuffers) == gl_MaxDrawBuffers) ? vec4(0, 1, 0, 1) : vec4(1, 0, 0, 1);
  45 }
  46 </script>
  47 <script>
  48 "use strict";
  49 description("This test verifies that compiling the same shader using GL_EXT_draw_buffers twice will have similar results on both rounds.");
  50
  51 debug("");
  52
  53 var wtu = WebGLTestUtils;
  54 var canvas = document.getElementById("canvas");
  55 var gl = wtu.create3DContext(canvas);
  56 var ext = null;
  57 var maxDrawBuffers;
  58
  59 if (!gl) {
  60   testFailed("WebGL context does not exist");
  61 } else {
  62   testPassed("WebGL context exists");
  63
  64   ext = gl.getExtension("WEBGL_draw_buffers");
  65   if (!ext) {
  66     testPassed("No WEBGL_draw_buffers support -- this is legal");
  67     finishTest();
  68   } else {
  69     testPassed("Successfully enabled WEBGL_draw_buffers extension");
  70     maxDrawBuffers = gl.getParameter(ext.MAX_DRAW_BUFFERS_WEBGL);
  71     runShadersTest();
  72     finishTest();
  73   }
  74 }
  75
  76 function testValueOfMaxDrawBuffers() {
  77   debug("Test the value of gl_MaxDrawBuffers in a shader");
  78   var fshader = wtu.replaceParams(wtu.getScript("fshaderTestMaxDrawBuffersValue"), {"gl_MaxDrawBuffers": maxDrawBuffers});
  79   var program = wtu.setupProgram(gl, ["vshader", fshader], ["a_position"], undefined, true);
  80   expectTrue(program != null, "Test program should compile");
  81   wtu.setupUnitQuad(gl);
  82   wtu.clearAndDrawUnitQuad(gl);
  83   wtu.checkCanvas(gl, [0, 255, 0, 255], "should be green to indicate that gl_MaxDrawBuffers had the right value");
  84   gl.deleteProgram(program);
  85   wtu.glErrorShouldBe(gl, gl.NO_ERROR, "there should be no errors");
  86 }
  87
  88 function runSingleTest(shaders, indexMsg) {
  89   var program = wtu.setupProgram(gl, shaders, ["a_position"], undefined, true);
  90   var programLinkedSuccessfully = (program != null);
  91   expectTrue(!programLinkedSuccessfully, "Program where gl_FragData is indexed by " + indexMsg + " should fail compilation.");
  92   gl.deleteProgram(program);
  93 }
  94
  95 function runShadersTest() {
  96   debug("MAX_DRAW_BUFFERS_WEBGL is: " + maxDrawBuffers);
  97
  98   // For reference, use a constant out-of-range parameter to test:
  99   debug("Test indexing gl_FragData with value of MAX_DRAW_BUFFERS_WEBGL");
 100   var fshader = wtu.replaceParams(wtu.getScript("fshaderConstantIndex"), {"gl_MaxDrawBuffers": maxDrawBuffers});
 101   runSingleTest(["vshader", fshader], maxDrawBuffers + " (value of MAX_DRAW_BUFFERS_WEBGL)");
 102
 103   debug("");
 104
 105   debug("Test indexing gl_FragData with gl_MaxDrawBuffers");
 106   debug("Repeat this test twice as that has revealed a bug.");
 107   for (var i = 0; i < 2; ++i) {
 108     runSingleTest(["vshader", "fshader"], "gl_MaxDrawBuffers");
 109   }
 110   wtu.glErrorShouldBe(gl, gl.NO_ERROR, "there should be no errors");
 111
 112   debug("");
 113
 114   testValueOfMaxDrawBuffers();
 115 }
 116 </script>
 117 </body>
 118 </html>