gl-fragcoord.html - mozsearch

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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

found in the LICENSE.txt file.

-->

<!DOCTYPE html>

<html>

<head>

<meta charset="utf-8">

<title>gl-fragcoord Test</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="32" height="32">

</canvas>

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

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

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

attribute vec4 vPosition;

void main()

  gl_Position = vPosition;

</script>

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

precision mediump float;

void main()

  gl_FragColor = vec4(

      floor(gl_FragCoord.x * 4.0 / 32.0) / 4.0,

      floor(gl_FragCoord.y * 4.0 / 32.0) / 4.0,

      floor(gl_FragCoord.z * 4.0) / 4.0,

1);

</script>

<script>

"use strict";

function init()

  description("tests gl_FragCoord");

  var wtu = WebGLTestUtils;

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

  var program = wtu.setupProgram(gl, ["vshader", "fshader"], ["vPosition"]);

  var vertexObject = gl.createBuffer();

  gl.bindBuffer(gl.ARRAY_BUFFER, vertexObject);

  gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(

      [-1, -1, -1,  1, -1,  0, -1,  1,  0,

       -1,  1,  0,  1, -1,  0,  1,  1,  1]),

      gl.STATIC_DRAW);

  gl.enableVertexAttribArray(0);

  gl.vertexAttribPointer(0, 3, gl.FLOAT, false, 0, 0);

  gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);

  gl.drawArrays(gl.TRIANGLES, 0, 6);

  wtu.glErrorShouldBe(gl, gl.NO_ERROR, "no errors from draw");

  for (var xx = 0; xx < 32; xx += 4) {

    for (var yy = 0; yy < 32; yy += 4) {

      var zz = (xx / 64) + (yy / 64);

      var color = [

        Math.floor(Math.floor(xx * 4.0 / 32.0) / 4 * 256),

        Math.floor(Math.floor(yy * 4.0 / 32.0) / 4 * 256),

        Math.floor(Math.floor(zz * 4.0) / 4 * 256)

];

      var msg = "should be " + color;

      wtu.checkCanvasRect(gl, xx, yy, 1, 1, color, msg, 4);

init();

var successfullyParsed = true;

</script>

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

</body>

</html>