<!--
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 Disabled Vertex Attrib Update 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="50" height="50">
</canvas>
<div id="description"></div>
<div id="console"></div>
<script id="vshader" type="x-shader/x-vertex">
attribute vec4 a_position;
attribute float a_actualValue;
uniform float u_expectedValue;
varying float v_result;
void main() {
  gl_Position = a_position;
  v_result = a_actualValue == u_expectedValue ? 1.0 : 0.0;
}
</script>

<script id="fshader" type="x-shader/x-fragment">
precision mediump float;
varying float v_result;
void main() {
  gl_FragColor = v_result > 0.0 ? vec4(0.0, 1.0, 0.0, 1.0) : vec4(1.0, 0.0, 0.0, 1.0);
}
</script>

<script>
// Tests that repeatedly updating a disabled vertex attribute works as expected.
// This covers an ANGLE bug where dirty bits for current values were ignoring repeated updates.
// Based on ANGLE test (VertexAttributeTest, DisabledAttribUpdates) from https://github.com/google/angle/blob/f7f0b8c3ab21c52cc2915048959361cf628d95f0/src/tests/gl_tests/VertexAttributeTest.cpp
"use strict";
var wtu = WebGLTestUtils;
description();

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

var program = wtu.setupProgram(gl, ['vshader', 'fshader']);
gl.useProgram(program);

var positionLocation = gl.getAttribLocation(program, "a_position");
var attribLoc = gl.getAttribLocation(program, "a_actualValue");
gl.vertexAttribPointer(attribLoc, 1, gl.FLOAT, gl.FALSE, 0, 0);

var uniLoc = gl.getUniformLocation(program, "u_expectedValue");

var gridRes = 1;
wtu.setupIndexedQuad(gl, gridRes, positionLocation);

var testValues = [1, 2, 3, 4];
for (var i = 0; i < testValues.length; ++i) {
  var testValue = testValues[i];
  gl.uniform1f(uniLoc, testValue);
  gl.vertexAttrib1f(attribLoc, testValue);
  wtu.clearAndDrawIndexedQuad(gl, gridRes);
  wtu.checkCanvas(gl, [0, 255, 0, 255], "should be green");
}

wtu.glErrorShouldBe(gl, gl.NO_ERROR, "should be no errors");

var successfullyParsed = true;
</script>
<script src="../../js/js-test-post.js"></script>

</body>
</html>

