gl-max-texture-dimensions.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 the max advertized texture size is supported.</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>

<canvas id="example" width="4" height="4" style="width: 40px; height: 30px;"></canvas>

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

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

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

attribute vec4 vPosition;

attribute vec2 texCoord0;

varying vec2 texCoord;

void main()

    gl_Position = vPosition;

    texCoord = texCoord0;

</script>

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

precision mediump float;

uniform samplerCube tex;

varying vec2 texCoord;

void main()

    gl_FragColor = textureCube(tex, normalize(vec3(texCoord, 1)));

</script>

<script>

"use strict";

description(document.title);

var wtu = WebGLTestUtils;

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

var program = wtu.setupTexturedQuad(gl);

function shouldBePowerOfTwo(n, name) {

    var power = Math.round(Math.log(n) / Math.log(2));

    if (Math.pow(2, power) == n) {

        testPassed(name + ' is a power of two.');

    } else {

        testFailed(name + ' should be a power of two, but was ' + n);

// Note: It seems like a reasonable assuption that a 1xN texture size should

// work. Even 1 by 128k is only 512k

var maxSize = gl.getParameter(gl.MAX_TEXTURE_SIZE);

debug("advertised max size: " + maxSize);

debug("verifying max size is power-of-two (implied by GLES 2.0 section 3.7.1)");

shouldBePowerOfTwo(maxSize, 'Max size');

var testSize = Math.min(maxSize, 128 * 1024);

var pixels = new Uint8Array(testSize * 4);

for (var ii = 0; ii < testSize; ++ii) {

  var off = ii * 4;

  pixels[off + 0] = 0;

  pixels[off + 1] = 255;

  pixels[off + 2] = 128;

  pixels[off + 3] = 255;

var tex = gl.createTexture();

gl.bindTexture(gl.TEXTURE_2D, tex);

debug("test " + testSize + "x1");

gl.texImage2D(

    gl.TEXTURE_2D, 0, gl.RGBA, testSize, 1, 0, gl.RGBA, gl.UNSIGNED_BYTE,

    pixels);

gl.generateMipmap(gl.TEXTURE_2D);

wtu.clearAndDrawUnitQuad(gl);

wtu.checkCanvas(gl, [0, 255, 128, 255],

                "Should be 0, 255, 128, 255");

debug("test 1x" + testSize);

gl.texImage2D(

    gl.TEXTURE_2D, 0, gl.RGBA, 1, testSize, 0, gl.RGBA, gl.UNSIGNED_BYTE,

    pixels);

gl.generateMipmap(gl.TEXTURE_2D);

wtu.clearAndDrawUnitQuad(gl);

wtu.checkCanvas(gl, [0, 255, 128, 255],

                "Should be 0, 255, 128, 255");

var program = wtu.setupProgram(

    gl, ['vshader', 'fshader'], ['vPosition', 'texCoord0'], [0, 1]);

wtu.glErrorShouldBe(gl, gl.NO_ERROR, "Should be no errors.");

// NOTE: We can't easily test cube maps because they require width == height

// and we might not have enough memory for maxSize by maxSize texture.

var successfullyParsed = true;

</script>

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

</body>

</html>