out-of-bounds-uniform-array-access.html

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Copyright (c) 2019 The Khronos Group Inc.

Use of this source code is governed by an MIT-style license that can be

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<!DOCTYPE html>

<html>

<head>

<meta charset="utf-8">

<title>WebGL out of bounds uniform array access.</title>

<link rel="stylesheet" href="../resources/js-test-style.css"/>

<script src="../js/js-test-pre.js"></script>

<script src="../js/webgl-test-utils.js"> </script>

</head>

<body style="background: #666;">

<div id="description"></div>

<div id="console"></div>

<div>elem mult: <span id="elemMultDisplay"></span></div>

<input type="range" id="elemMult" value="4" min="0" max="2048" style="width: 100%;"/>

<div>line width: <span id="lineWidthDisplay"></span></div>

<input type="range" id="lineWidth" value="512" min="0" max="2540" style="width: 100%;"/>

<canvas id="example" width="256" height="256" style="background: black;">

</canvas>

<script id="vshader" type="x-shader/x-vertex">

attribute vec4 vPosition;

varying vec4 v_color;

uniform float lineWidth;

uniform int elemMult;

uniform vec4 someArray[2];

void main()

    vec2 texcoord = vec2(vPosition.xy * 0.5 + vec2(0.5, 0.5));

    int index = int(texcoord.x + texcoord.y * lineWidth) * elemMult;

    v_color = someArray[index];

    gl_Position = vPosition;

</script>

<script id="fshader" type="x-shader/x-fragment">

precision mediump float;

varying vec4 v_color;

void main()

  gl_FragColor = v_color * vec4(1.0 / 256.0, 1.0 / 256.0, 1.0 / 256.0, 1.0 / 256.0) + vec4(0,0,0,0.5);

</script>

<script>

"use strict";

window.onload = main;

debug("Tests a WebGL program that accesses out of bounds uniform array elements");

function main() {

  var wtu = WebGLTestUtils;

  var gl = wtu.create3DContext("example");

  var program = wtu.setupProgram(

gl,

      ['vshader', 'fshader'],

      ['vPosition'], [0]);

  var gridRes = 255;

  wtu.setupIndexedQuad(gl, gridRes, 0);

  var lineWidthLoc = gl.getUniformLocation(program, "lineWidth");

  var elemMultLoc = gl.getUniformLocation(program, "elemMult");

  assertMsg(gl.getError() == gl.NO_ERROR, "Should be no errors from setup.");

  var lineWidth = 512;

  var lineWidthElem = document.getElementById("lineWidth");

  var lineWidthDisplayElem = document.getElementById("lineWidthDisplay");

  lineWidthElem.value = lineWidth;

  lineWidthElem.addEventListener('change', function(event) {

      //console.log(event.target.value);

      lineWidth = event.target.value;

      draw();

    }, false);

  var elemMult = 4;

  var elemMultElem = document.getElementById("elemMult");

  var elemMultDisplayElem = document.getElementById("elemMultDisplay");

  elemMultElem.value = elemMult;

  elemMultElem.addEventListener('change', function(event) {

      //console.log(event.target.value);

      elemMult = event.target.value;

      draw();

    }, false);

  draw();

  function draw() {

    lineWidthDisplayElem.innerText = lineWidth;

    elemMultDisplayElem.innerText = elemMult;

    gl.uniform1f(lineWidthLoc, lineWidth);

    gl.uniform1i(elemMultLoc, elemMult);

    gl.drawElements(gl.TRIANGLES, gridRes * gridRes * 6, gl.UNSIGNED_SHORT, 0);

  var successfullyParsed = true;

</script>

</body>

</html>