out-of-bounds-index-buffers.html (5703B)
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>