dom/canvas/test/webgl-conf/checkout/conformance/rendering/out-of-bounds-index-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 <!DOCTYPE html>
   7 <html>
   8 <head>
   9 <meta charset="utf-8">
  10 <link rel="stylesheet" href="../../resources/js-test-style.css"/>
  11 <script src="../../js/js-test-pre.js"></script>
  12 <script src="../../js/webgl-test-utils.js"></script>
  13 <title>WebGL Out-of-Bounds Index Buffer Conformance Test</title>
  14 </head>
  15 <body>
  16 <canvas id="canvas" width="8" height="8" style="width: 100px; height: 100px;"></canvas>
  17 <div id="description"></div>
  18 <div id="console"></div>
  19 <script id="vsCheckOutOfBounds" type="x-shader/x-vertex">
  20     precision mediump float;
  21     attribute vec2 position;
  22     attribute vec4 vecRandom;
  23     varying vec4 v_color;
  24
  25     // Per the spec, each component can either contain existing contents
  26     // of the buffer or 0.
  27     bool testFloatComponent(float component) {
  28         return (component == 0.2 || component == 0.0);
  29     }
  30     // The last component is additionally allowed to be 1.0.
  31     bool testLastFloatComponent(float component) {
  32         return testFloatComponent(component) || component == 1.0;
  33     }
  34
  35     void main() {
  36         if (testFloatComponent(vecRandom.x) &&
  37             testFloatComponent(vecRandom.y) &&
  38             testFloatComponent(vecRandom.z) &&
  39             testLastFloatComponent(vecRandom.w)) {
  40             v_color = vec4(0.0, 1.0, 0.0, 1.0); // green -- We're good
  41         } else {
  42             v_color = vec4(1.0, 0.0, 0.0, 1.0); // red -- Unexpected value
  43         }
  44         gl_Position = vec4(position, 0.0, 1.0);
  45     }
  46 </script>
  47 <script>
  48 "use strict";
  49 description("This test verifies that out-of-bounds index buffers behave according to spec.");
  50
  51 // Prepare an element array buffer that indexes out-of-bounds beginning with the start index passed in.
  52 // Ensure that drawElements flags either no error or INVALID_OPERATION. In the case of INVALID_OPERATION,
  53 // no canvas pixels can be touched.  In the case of NO_ERROR, all written values must either be the
  54 // zero vertex or a value in the vertex buffer.  See vsCheckOutOfBounds shader.
  55 function drawAndVerifyOutOfBoundsIndex(gl, startIndex) {
  56     gl.clearColor(0.0, 0.0, 1.0, 1.0);  // Start with blue to indicate no pixels touched.
  57     gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
  58
  59     prepareElementArrayBuffer(gl, /*StartIndex*/startIndex);
  60
  61     gl.drawElements(gl.TRIANGLE_STRIP, 4, gl.UNSIGNED_SHORT, /*offset*/0);
  62     var error = gl.getError();
  63     if (error === gl.INVALID_OPERATION) {
  64         testPassed("drawElements flagged INVALID_OPERATION, which is valid so long as all canvas pixels were not touched.");
  65         wtu.checkCanvas(gl, [0, 0, 255, 255]);
  66     } else if (error === gl.NO_ERROR) {
  67         testPassed("drawElements flagged NO_ERROR, which is valid so long as all canvas pixels are green.");
  68         wtu.checkCanvas(gl, [0, 255, 0, 255]);
  69     } else {
  70         testFailed("Invalid error flagged by drawElements. Should be INVALID_OPERATION or NO_ERROR");
  71     }
  72 }
  73
  74 // Create an element array buffer with a tri-strip that starts at startIndex and make
  75 // it the active element array buffer.
  76 function prepareElementArrayBuffer(gl, startIndex) {
  77     var glElementArrayBuffer = gl.createBuffer();
  78     gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, glElementArrayBuffer);
  79     var quadIndices = new Uint16Array(4);
  80     for (var i = 0; i < quadIndices.length; i++) {
  81         quadIndices[i] = startIndex + i;
  82     }
  83     gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, quadIndices, gl.STATIC_DRAW);
  84 }
  85
  86
  87 var wtu = WebGLTestUtils;
  88 var canvas = document.getElementById("canvas");
  89 var gl = wtu.create3DContext(canvas, {antialias: false});
  90
  91 var numberOfQuads = 200;
  92
  93 // Create a vertex buffer with 200 properly formed tri-strip quads. These quads will cover the canvas texture
  94 // such that every single pixel is touched by the fragment shader.
  95 var glQuadBuffer = gl.createBuffer();
  96 gl.bindBuffer(gl.ARRAY_BUFFER, glQuadBuffer);
  97 var quadPositions = new Float32Array(numberOfQuads * /*ComponentsPerQuad*/2 * /*VerticesPerQuad*/4);
  98 for (var i = 0; i < quadPositions.length; i += /*ComponentsPerQuad*/2 * /*VerticesPerQuad*/4) {
  99     quadPositions[i+0] = -1.0;  // upper left
 100     quadPositions[i+1] =  1.0;
 101     quadPositions[i+2] =  1.0;  // upper right
 102     quadPositions[i+3] =  1.0;
 103     quadPositions[i+4] = -1.0;  // lower left
 104     quadPositions[i+5] = -1.0;
 105     quadPositions[i+6] =  1.0;  // lower right
 106     quadPositions[i+7] = -1.0;
 107 }
 108 gl.bufferData(gl.ARRAY_BUFFER, quadPositions, gl.STATIC_DRAW);
 109 gl.enableVertexAttribArray(0);
 110 gl.vertexAttribPointer(0, 2, gl.FLOAT, false, 0, 0);
 111
 112 // Create a small vertex buffer with determined-ahead-of-time "random" values (0.2). This buffer will be
 113 // the one indexed off the end.
 114 var glVertexBuffer = gl.createBuffer();
 115 gl.bindBuffer(gl.ARRAY_BUFFER, glVertexBuffer);
 116 gl.bufferData(gl.ARRAY_BUFFER, new Float32Array([0.2, 0.2, 0.2, 0.2]), gl.STATIC_DRAW);
 117 gl.enableVertexAttribArray(1);
 118 gl.vertexAttribPointer(1, 4, gl.FLOAT, false, 0, 0);
 119
 120 // Setup the verification program.
 121 var glProgram = wtu.setupProgram(gl, ["vsCheckOutOfBounds", wtu.simpleVertexColorFragmentShader], ["position", "vecRandom"]);
 122 wtu.glErrorShouldBe(gl, gl.NO_ERROR, "Shader and buffer setup should not generate errors");
 123
 124 debug("Test -- Index off the end of the vertex buffer near the beginning of the out of bounds area.");
 125 drawAndVerifyOutOfBoundsIndex(gl, /*StartIndex*/4);
 126
 127 debug("");
 128
 129 debug("Test -- Index off the end of the vertex buffer near the end of the out of bounds area.")
 130 drawAndVerifyOutOfBoundsIndex(gl, /*StartIndex*/numberOfQuads - 4);
 131
 132 var successfullyParsed = true;
 133 </script>
 134 <script src="../../js/js-test-post.js"></script>
 135 </body>
 136 </html>