<!--
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>GLSL function nodes Test</title>
<link rel="stylesheet" href="../../../resources/js-test-style.css"/>
<link rel="stylesheet" href="../../../resources/glsl-feature-tests.css"/>
<script src="../../../js/js-test-pre.js"></script>
<script src="../../../js/webgl-test-utils.js"> </script>

<script id="vshaderNoBranch" type="x-shader/x-vertex">
attribute vec3 aPosition;
uniform float redIntensity;

varying vec4 vColor;

float MADBug(float paramValue) {
  float localVar = 1.0;
  return 0.25 * ceil(localVar) + paramValue;
}

void main(void) {
    gl_Position = vec4(aPosition, 1.0);
    vColor = vec4(MADBug(redIntensity), 0., 0., 1.);
}
</script>

<script id="vshaderBranch" type="x-shader/x-vertex">
attribute vec3 aPosition;
uniform float redIntensity;

varying vec4 vColor;

float MADBug(float paramValue) {
  float localVar = 1.0;
  return 0.25 * ceil(localVar) + paramValue;
}

void main(void) {
    float condition = 42.;
    if (condition == 0.) {}
    gl_Position = vec4(aPosition, 1.0);
    vColor = vec4(MADBug(redIntensity), 0., 0., 1.);
}
</script>

<script id="fshader" type="x-shader/x-fragment">
precision mediump float;

varying vec4 vColor;
void main()
{
   gl_FragColor = vColor;
}
</script>
</head>
<body>
<canvas id="canvasNoBranch" width="50" height="50"></canvas>
<canvas id="canvasBranch" width="50" height="50"></canvas>
<div id="description">This tests against a Mac driver bug related to branches
 inside of Vertex Shaders.</div>
<div id="console"></div>
<script>
"use strict";
var width = 50;
var height = 50;
var wtu = WebGLTestUtils;

function drawAndRead(canvasID, vshaderID, buffer)
{
    var gl = wtu.create3DContext(canvasID);
    var program = wtu.setupProgram(gl, [vshaderID, "fshader"], ["aPosition"]);
    var vertexObject = gl.createBuffer();
    gl.bindBuffer(gl.ARRAY_BUFFER, vertexObject);
    gl.bufferData(gl.ARRAY_BUFFER, new Float32Array([ 0,0.5,0, -1,-1,0, 1,-1,0 ]), gl.STATIC_DRAW);
    gl.enableVertexAttribArray(0);
    gl.vertexAttribPointer(0, 3, gl.FLOAT, false, 0, 0);

    var loc = gl.getUniformLocation(program, "redIntensity");
    gl.uniform1f(loc, 0.75);
    gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
    gl.drawArrays(gl.TRIANGLES, 0, 3);
    gl.readPixels(0, 0, width, height, gl.RGBA, gl.UNSIGNED_BYTE, buffer);
    if (gl.getError() != gl.NO_ERROR)
        return false;
    return true;
}

function compareRendering(buffer1, buffer2, tol)
{
    for (var i = 0; i < width * height * 4; ++i) {
        if (Math.abs(buffer1[i] - buffer2[i]) > tol)
            return false;
    }
    return true;
}

function init()
{
    description("tests vertex shader with branch");

    var bufBranch = new Uint8Array(width * height * 4);
    var bufNoBranch = new Uint8Array(width * height * 4);

    if (drawAndRead("canvasBranch", "vshaderBranch", bufBranch) == false ||
        drawAndRead("canvasNoBranch", "vshaderNoBranch", bufNoBranch) == false) {
        testFailed("Setup failed");
    } else {
        if (compareRendering(bufBranch, bufNoBranch, 4) == false)
            testFailed("Rendering results are different");
        else
            testPassed("Rendering results are the same");
    }
}

init();
var successfullyParsed = true;
</script>
<script src="../../../js/js-test-post.js"></script>
</body>
</html>

