vertex-texture-fetch.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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<html>

<head>

<meta charset="utf-8">

<title>WebGL Vertex Texture Fetch.</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="1" height="1" style="width: 40px; height: 40px;"></canvas>

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

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

<script id="vs" type="text/something-not-javascript">

attribute vec4 a_position;

attribute vec2 a_texCoord;

uniform sampler2D u_texture;

varying vec4 color;

void main() {

    gl_Position = a_position;

    color = texture2D(u_texture, a_texCoord);

</script>

<script id="fs" type="text/something-not-javascript">

precision mediump float;

varying vec4 color;

void main() {

    gl_FragColor = color;

</script>

<script>

"use strict";

description("checks that vertex texture fetch, if supported, operates correctly.");

var wtu = WebGLTestUtils;

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

if (!gl.getParameter(gl.MAX_VERTEX_TEXTURE_IMAGE_UNITS)) {

  testPassed("No vertex texture image units (vertex texture fetch not supported) -- this is legal");

} else {

  var texture = gl.createTexture();

  gl.bindTexture(gl.TEXTURE_2D, texture);

  gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, 2, 2, 0, gl.RGBA, gl.UNSIGNED_BYTE,

                new Uint8Array([

                    255, 0, 0, 255,

                    0, 255, 0, 255,

                    0, 0, 255, 255,

                    255, 255, 0, 255]));

  gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST);

  gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST);

  gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);

  gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);

  wtu.glErrorShouldBe(gl, gl.NO_ERROR, "after creating texture");

  var program = wtu.setupProgram(gl, ["vs", "fs"], ["vPosition", "vTexCoord"]);

  gl.uniform1i(gl.getUniformLocation(program, "u_texture"), 0);

  gl.disable(gl.BLEND);

  gl.disable(gl.DEPTH_TEST);

  wtu.glErrorShouldBe(gl, gl.NO_ERROR, "after initWebGL");

  var bufferObjects = wtu.setupUnitQuad(gl, 0);

  gl.disableVertexAttribArray(1);

  gl.vertexAttrib2f(1, 0, 0);

  wtu.clearAndDrawUnitQuad(gl);

  wtu.checkCanvas(gl, [255, 0, 0, 255], "Should be red.");

  gl.vertexAttrib2f(1, 1, 0);

  wtu.clearAndDrawUnitQuad(gl);

  wtu.checkCanvas(gl, [0, 255, 0, 255], "Should be green.");

  gl.vertexAttrib2f(1, 0, 1);

  wtu.clearAndDrawUnitQuad(gl);

  wtu.checkCanvas(gl, [0, 0, 255, 255], "Should be blue.");

  gl.vertexAttrib2f(1, 1, 1);

  wtu.clearAndDrawUnitQuad(gl);

  wtu.checkCanvas(gl, [255, 255, 0, 255], "Should be yellow.");

  wtu.glErrorShouldBe(gl, gl.NO_ERROR, "after drawing");

var successfullyParsed = true;

</script>

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</body>

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