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

</body>
</html>
