<!--
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,
            0
        ];
        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>
