gl-frontfacing.html

Enable keyboard shortcuts

<!--

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(

      gl_FrontFacing ? 1.0 : 0.0,

      gl_FrontFacing ? 0.0 : 1.0,

0,

1);

</script>

<script>

"use strict";

function init()

  description("tests gl_FrontFacing");

  var wtu = WebGLTestUtils;

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

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

  var gridRes = 4;

  wtu.setupIndexedQuad(gl, gridRes, 0, true);

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

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

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

  var step = 32 / gridRes;

  var halfStep = step / 2;

  var quarterStep = halfStep / 2;

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

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

      for (var ii = 0; ii < 2; ++ii) {

        var color = [

            ii == 0 ? 255 : 0,

            ii == 0 ? 0 : 255,

];

        var msg = "should be " + color;

        wtu.checkCanvasRect(

gl,

            xx + quarterStep + halfStep * ii,

            yy + quarterStep + halfStep * ii,

            1, 1, color, msg, 4);

init();

var successfullyParsed = true;

</script>

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

</body>

</html>