dom/canvas/test/webgl-conf/checkout/conformance/reading/fbo-remains-unchanged-after-read-pixels.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 </head>
  15 <body>
  16 <div id="description"></div>
  17 <div id="console"></div>
  18 <canvas id="canvas" width="4" height="4"></canvas>
  19 <script id="vshader" type="x-shader/x-vertex">
  20 attribute vec3 a_pos;
  21 attribute vec4 a_color;
  22 varying vec4 v_color;
  23
  24 void main()
  25 {
  26     v_color = a_color;
  27     gl_Position = vec4(a_pos.xyz, 1.0);
  28 }
  29 </script>
  30
  31 <script id="fshader" type="x-shader/x-fragment">
  32 precision mediump float;
  33
  34 varying vec4 v_color;
  35
  36 void main()
  37 {
  38     gl_FragColor = v_color;
  39 }
  40 </script>
  41
  42 <script>
  43 "use strict";
  44
  45 description("when antialias is enabled, verify default fbo pixels would not be changed between two readPixels without drawing operations");
  46 var wtu = WebGLTestUtils;
  47 var N = 4;
  48
  49 var vertices = new Float32Array([
  50          1.0, 1.0, 0.0,
  51         -1.0, -1.0, 0.0]);
  52 var colors = new Uint8Array([
  53         255, 0, 0, 255,
  54         255, 0, 0, 255]);
  55
  56 var canvas = document.getElementById('canvas');
  57 var gl = wtu.create3DContext(canvas, {antialias: true});
  58
  59 if (!gl) {
  60   testFailed("context does not exist");
  61 } else {
  62   testPassed("context exists");
  63
  64   var program = wtu.setupProgram(gl, ["vshader", "fshader"], ["a_pos", "a_color"]);
  65   gl.clearColor(0, 0, 0, 1);
  66   gl.clear(gl.COLOR_BUFFER_BIT);
  67
  68   var colorOffset = vertices.byteLength;
  69   var vbo = gl.createBuffer();
  70   gl.bindBuffer(gl.ARRAY_BUFFER, vbo);
  71   gl.bufferData(gl.ARRAY_BUFFER, colorOffset + colors.byteLength, gl.STATIC_DRAW);
  72   gl.bufferSubData(gl.ARRAY_BUFFER, 0, vertices);
  73   gl.bufferSubData(gl.ARRAY_BUFFER, colorOffset, colors);
  74
  75   gl.vertexAttribPointer(0, 3, gl.FLOAT, false, 0, 0);
  76   gl.enableVertexAttribArray(0);
  77   gl.vertexAttribPointer(1, 4, gl.UNSIGNED_BYTE, true, 0, colorOffset);
  78   gl.enableVertexAttribArray(1);
  79   gl.drawArrays(gl.LINES, 0, vertices.length / 3);
  80
  81   var result_1 = new Uint8Array(N * N * 4);
  82   var result_2 = new Uint8Array(N * N * 4);
  83   gl.readPixels(0, 0, N, N, gl.RGBA, gl.UNSIGNED_BYTE, result_1);
  84   gl.readPixels(0, 0, N, N, gl.RGBA, gl.UNSIGNED_BYTE, result_2);
  85   wtu.glErrorShouldBe(gl, gl.NO_ERROR);
  86
  87   var tolerance = 0;
  88   var diff = new Uint8Array(N * N * 4);
  89   var failed = wtu.comparePixels(result_1, result_2, tolerance, diff);
  90
  91   if (failed) {
  92     testFailed("default fbo pixels had be changed between two readPixels without drawing operations");
  93   } else {
  94     testPassed("default fbo pixels had not be changed between two readPixels without drawing operations.");
  95   }
  96
  97   gl.bindBuffer(gl.ARRAY_BUFFER, null);
  98   gl.deleteBuffer(vbo);
  99 }
 100
 101 var successfullyParsed = true;
 102 </script>
 103 <script src="../../js/js-test-post.js"></script>
 104 </body>
 105 </html>