<!--
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>
