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oit.html
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<!DOCTYPE html>
<!--
The MIT License (MIT)
Copyright (c) 2017 Tarek Sherif
Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
the Software, and to permit persons to whom the Software is furnished to do so,
subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
-->
<!--
Based on "Weighted Blended Order-Independent Transparency"
By Morgan McGuire and Louis Bavoil
http://jcgt.org/published/0002/02/09/
-->
<html>
<head>
<title>WebGL 2 Example: Order-independent Transparency</title>
<meta charset="utf-8">
<script src="utils/gl-matrix.js"></script>
<script src="utils/utils.js"></script>
<link rel="stylesheet" href="css/webgl2examples.css">
</head>
<body>
<div id="example-title">
<header>WebGL 2 Example: Weighted, Blended Order-independent Transparency</header>
<div id="features">
Features: Vertex Arrays, Uniform Buffers, Immutable Textures, Multiple Render Targets, Float Textures, texelFetch, Hardware Instancing, EXT_color_buffer_float
</div>
<div>
<a href="https://github.com/tsherif/webgl2examples/blob/master/oit.html">Source code</a>
</div>
</div>
<canvas id="gl-canvas"></canvas>
<script type="x-shader/vs" id="vertex-accum">
#version 300 es
layout(std140, column_major) uniform;
layout(location=0) in vec4 position;
layout(location=1) in vec2 uv;
layout(location=2) in vec3 normal;
layout(location=3) in vec4 color;
layout(location=4) in mat4 modelMatrix;
uniform SceneUniforms {
mat4 uViewProj;
vec4 uEyePosition;
vec4 uLightPosition;
};
out vec3 vPosition;
out vec2 vUV;
out vec3 vNormal;
flat out vec4 vColor;
void main() {
vec4 worldPosition = modelMatrix * position;
vPosition = worldPosition.xyz;
vUV = uv;
vNormal = mat3(modelMatrix) * normal;
vColor = color;
gl_Position = uViewProj * worldPosition;
}
</script>
<script type="x-shader/fs" id="fragment-accum">
#version 300 es
precision highp float;
layout(std140, column_major) uniform;
uniform SceneUniforms {
mat4 uViewProj;
vec4 uEyePosition;
vec4 uLightPosition;
};
uniform sampler2D uTexture;
in vec3 vPosition;
in vec2 vUV;
in vec3 vNormal;
flat in vec4 vColor;
layout(location=0) out vec4 accumColor;
layout(location=1) out float accumAlpha;
float weight(float z, float a) {
return clamp(pow(min(1.0, a * 10.0) + 0.01, 3.0) * 1e8 * pow(1.0 - z * 0.9, 3.0), 1e-2, 3e3);
}
void main() {
vec3 position = vPosition.xyz;
vec3 normal = normalize(vNormal.xyz);
vec2 uv = vUV;
vec4 baseColor = vColor * texture(uTexture, uv);
vec3 eyeDirection = normalize(uEyePosition.xyz - position);
vec3 lightVec = uLightPosition.xyz - position;
vec3 lightDirection = normalize(lightVec);
vec3 reflectionDirection = reflect(-lightDirection, normal);
float nDotL = max(dot(lightDirection, normal), 0.0);
float diffuse = nDotL;
float ambient = 0.2;
float specular = pow(max(dot(reflectionDirection, eyeDirection), 0.0), 20.0);
vec4 color = vec4((ambient + diffuse + specular) * baseColor.rgb, vColor.a);
color.rgb *= color.a;
float w = weight(gl_FragCoord.z, color.a);
accumColor = vec4(color.rgb * w, color.a);
accumAlpha = color.a * w;
}
</script>
<script type="x-shader/vs" id="vertex-quad">
#version 300 es
layout(location=0) in vec4 aPosition;
void main() {
gl_Position = aPosition;
}
</script>
<script type="x-shader/fs" id="fragment-draw">
#version 300 es
precision highp float;
uniform sampler2D uAccumulate;
uniform sampler2D uAccumulateAlpha;
out vec4 fragColor;
void main() {
ivec2 fragCoord = ivec2(gl_FragCoord.xy);
vec4 accum = texelFetch(uAccumulate, fragCoord, 0);
float a = 1.0 - accum.a;
accum.a = texelFetch(uAccumulateAlpha, fragCoord, 0).r;
fragColor = vec4(a * accum.rgb / clamp(accum.a, 0.001, 50000.0), a);
}
</script>
<script>
var canvas = document.getElementById("gl-canvas");
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
var gl = canvas.getContext("webgl2");
if (!gl) {
console.error("WebGL 2 not available");
document.body.innerHTML = "This example requires WebGL 2 which is unavailable on this system."
}
gl.clearColor(0.0, 0.0, 0.0, 1.0);
gl.enable(gl.BLEND);
gl.depthMask(false);
if (!gl.getExtension("EXT_color_buffer_float")) {
console.error("FLOAT color buffer not available");
document.body.innerHTML = "This example requires EXT_color_buffer_float which is unavailable on this system."
}
/////////////////////////
// OBJECT DESCRIPTIONS
/////////////////////////
var NUM_SPHERES = 32;
var NUM_PER_ROW = 8;
var RADIUS = 0.6;
var spheres = new Array(NUM_SPHERES);
var colorData = new Float32Array(NUM_SPHERES * 4);
var modelMatrixData = new Float32Array(NUM_SPHERES * 16);
for (var i = 0; i < NUM_SPHERES; ++i) {
var angle = 2 * Math.PI * (i % NUM_PER_ROW) / NUM_PER_ROW;
var x = Math.sin(angle) * RADIUS;
var y = Math.floor(i / NUM_PER_ROW) / (NUM_PER_ROW / 4) - 0.75;
var z = Math.cos(angle) * RADIUS;
spheres[i] = {
scale: [0.8, 0.8, 0.8],
rotate: [0, 0, 0], // Will be used for global rotation
translate: [x, y, z],
modelMatrix: mat4.create()
};
colorData.set(vec4.fromValues(
Math.sqrt(Math.random()),
Math.sqrt(Math.random()),
Math.sqrt(Math.random()),
0.5
), i * 4);
}
/////////////////////////
// ACCUMULATION PROGRAM
/////////////////////////
var accumVsSource = document.getElementById("vertex-accum").text.trim();
var accumFsSource = document.getElementById("fragment-accum").text.trim();
var accumVertexShader = gl.createShader(gl.VERTEX_SHADER);
gl.shaderSource(accumVertexShader, accumVsSource);
gl.compileShader(accumVertexShader);
if (!gl.getShaderParameter(accumVertexShader, gl.COMPILE_STATUS)) {
console.error(gl.getShaderInfoLog(accumVertexShader));
}
var accumFragmentShader = gl.createShader(gl.FRAGMENT_SHADER);
gl.shaderSource(accumFragmentShader, accumFsSource);
gl.compileShader(accumFragmentShader);
if (!gl.getShaderParameter(accumFragmentShader, gl.COMPILE_STATUS)) {
console.error(gl.getShaderInfoLog(accumFragmentShader));
}
var accumProgram = gl.createProgram();
gl.attachShader(accumProgram, accumVertexShader);
gl.attachShader(accumProgram, accumFragmentShader);
gl.linkProgram(accumProgram);
if (!gl.getProgramParameter(accumProgram, gl.LINK_STATUS)) {
console.error(gl.getProgramInfoLog(accumProgram));
}
/////////////////////
// DRAW PROGRAM
/////////////////////
var quadVsSource = document.getElementById("vertex-quad").text.trim();
var drawFsSource = document.getElementById("fragment-draw").text.trim();
var drawVertexShader = gl.createShader(gl.VERTEX_SHADER);
gl.shaderSource(drawVertexShader, quadVsSource);
gl.compileShader(drawVertexShader);
if (!gl.getShaderParameter(drawVertexShader, gl.COMPILE_STATUS)) {
console.error(gl.getShaderInfoLog(drawVertexShader));
}
var drawFragmentShader = gl.createShader(gl.FRAGMENT_SHADER);
gl.shaderSource(drawFragmentShader, drawFsSource);
gl.compileShader(drawFragmentShader);
if (!gl.getShaderParameter(drawFragmentShader, gl.COMPILE_STATUS)) {
console.error(gl.getShaderInfoLog(drawFragmentShader));
}
var drawProgram = gl.createProgram();
gl.attachShader(drawProgram, drawVertexShader);
gl.attachShader(drawProgram, drawFragmentShader);
gl.linkProgram(drawProgram);
if (!gl.getProgramParameter(drawProgram, gl.LINK_STATUS)) {
console.error(gl.getProgramInfoLog(drawProgram));
}
/////////////////////////
// GET UNIFORM LOCATIONS
/////////////////////////
var sceneUniformsLocation = gl.getUniformBlockIndex(accumProgram, "SceneUniforms");
gl.uniformBlockBinding(accumProgram, sceneUniformsLocation, 0);
var modelMatrixLocation = gl.getUniformLocation(accumProgram, "uModel");
var textureLocation = gl.getUniformLocation(accumProgram, "uTexture");
var accumLocation = gl.getUniformLocation(drawProgram, "uAccumulate");
var accumAlphaLocation = gl.getUniformLocation(drawProgram, "uAccumulateAlpha");
////////////////////////////////
// SET UP FRAMEBUFFERS
////////////////////////////////
var accumBuffer = gl.createFramebuffer();
gl.bindFramebuffer(gl.FRAMEBUFFER, accumBuffer);
gl.activeTexture(gl.TEXTURE0);
var accumTarget = gl.createTexture();
gl.bindTexture(gl.TEXTURE_2D, accumTarget);
gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, false);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_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);
gl.texStorage2D(gl.TEXTURE_2D, 1, gl.RGBA16F, gl.drawingBufferWidth, gl.drawingBufferHeight);
gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, accumTarget, 0);
var accumAlphaTarget = gl.createTexture();
gl.bindTexture(gl.TEXTURE_2D, accumAlphaTarget);
gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, false);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_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);
gl.texStorage2D(gl.TEXTURE_2D, 1, gl.R16F, gl.drawingBufferWidth, gl.drawingBufferHeight);
gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT1, gl.TEXTURE_2D, accumAlphaTarget, 0);
var depthTarget = gl.createTexture();
gl.bindTexture(gl.TEXTURE_2D, depthTarget);
gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, false);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_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);
gl.texStorage2D(gl.TEXTURE_2D, 1, gl.DEPTH_COMPONENT16, gl.drawingBufferWidth, gl.drawingBufferHeight);
gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.TEXTURE_2D, depthTarget, 0);
gl.drawBuffers([
gl.COLOR_ATTACHMENT0,
gl.COLOR_ATTACHMENT1
]);
gl.bindFramebuffer(gl.FRAMEBUFFER, null);
/////////////////////
// SET UP GEOMETRY
/////////////////////
var sphere = utils.createSphere({radius: 0.5});
var numVertices = sphere.positions.length / 3;
var sphereArray = gl.createVertexArray();
gl.bindVertexArray(sphereArray);
var positionBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);
gl.bufferData(gl.ARRAY_BUFFER, sphere.positions, gl.STATIC_DRAW);
gl.vertexAttribPointer(0, 3, gl.FLOAT, false, 0, 0);
gl.enableVertexAttribArray(0);
var uvBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, uvBuffer);
gl.bufferData(gl.ARRAY_BUFFER, sphere.uvs, gl.STATIC_DRAW);
gl.vertexAttribPointer(1, 2, gl.FLOAT, false, 0, 0);
gl.enableVertexAttribArray(1);
var normalBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, normalBuffer);
gl.bufferData(gl.ARRAY_BUFFER, sphere.normals, gl.STATIC_DRAW);
gl.vertexAttribPointer(2, 3, gl.FLOAT, false, 0, 0);
gl.enableVertexAttribArray(2);
var color = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, color);
gl.bufferData(gl.ARRAY_BUFFER, colorData, gl.STATIC_DRAW);
gl.vertexAttribPointer(3, 4, gl.FLOAT, false, 0, 0);
gl.vertexAttribDivisor(3, 1);
gl.enableVertexAttribArray(3);
// Columns of matrix as separate attributes for instancing
var matrixBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, matrixBuffer);
gl.bufferData(gl.ARRAY_BUFFER, modelMatrixData, gl.DYNAMIC_DRAW);
gl.vertexAttribPointer(4, 4, gl.FLOAT, false, 64, 0);
gl.vertexAttribPointer(5, 4, gl.FLOAT, false, 64, 16);
gl.vertexAttribPointer(6, 4, gl.FLOAT, false, 64, 32);
gl.vertexAttribPointer(7, 4, gl.FLOAT, false, 64, 48);
gl.vertexAttribDivisor(4, 1);
gl.vertexAttribDivisor(5, 1);
gl.vertexAttribDivisor(6, 1);
gl.vertexAttribDivisor(7, 1);
gl.enableVertexAttribArray(4);
gl.enableVertexAttribArray(5);
gl.enableVertexAttribArray(6);
gl.enableVertexAttribArray(7);
var indices = gl.createBuffer();
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, indices);
gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, sphere.indices, gl.STATIC_DRAW);
// Quad for draw pass
var quadArray = gl.createVertexArray();
gl.bindVertexArray(quadArray);
var quadPositionBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, quadPositionBuffer);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array([
-1, 1,
-1, -1,
1, -1,
-1, 1,
1, -1,
1, 1,
]), gl.STATIC_DRAW);
gl.vertexAttribPointer(0, 2, gl.FLOAT, false, 0, 0);
gl.enableVertexAttribArray(0);
//////////////////////
// SET UP UNIFORMS
//////////////////////
var projMatrix = mat4.create();
mat4.perspective(projMatrix, Math.PI / 2, canvas.width / canvas.height, 0.1, 10.0);
var viewMatrix = mat4.create();
var eyePosition = vec3.fromValues(0, 0.8, 2);
mat4.lookAt(viewMatrix, eyePosition, vec3.fromValues(0, 0, 0), vec3.fromValues(0, 1, 0));
var viewProjMatrix = mat4.create();
mat4.multiply(viewProjMatrix, projMatrix, viewMatrix);
var lightPosition = vec3.fromValues(1, 1, 2);
var sceneUniformData = new Float32Array(24);
sceneUniformData.set(viewProjMatrix);
sceneUniformData.set(eyePosition, 16);
sceneUniformData.set(lightPosition, 20);
var sceneUniformBuffer = gl.createBuffer();
gl.bindBufferBase(gl.UNIFORM_BUFFER, 0, sceneUniformBuffer);
gl.bufferData(gl.UNIFORM_BUFFER, sceneUniformData, gl.STATIC_DRAW);
var image = new Image();
image.onload = function() {
///////////////////////
// BIND TEXTURES
///////////////////////
var texture = gl.createTexture();
gl.activeTexture(gl.TEXTURE0);
gl.bindTexture(gl.TEXTURE_2D, texture);
gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, true);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR_MIPMAP_LINEAR);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.REPEAT);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.REPEAT);
var levels = levels = Math.floor(Math.log2(Math.max(this.width, this.height))) + 1;
gl.texStorage2D(gl.TEXTURE_2D, levels, gl.RGBA8, image.width, image.height);
gl.texSubImage2D(gl.TEXTURE_2D, 0, 0, 0, image.width, image.height, gl.RGBA, gl.UNSIGNED_BYTE, image);
gl.generateMipmap(gl.TEXTURE_2D);
gl.activeTexture(gl.TEXTURE1);
gl.bindTexture(gl.TEXTURE_2D, accumTarget);
gl.activeTexture(gl.TEXTURE2);
gl.bindTexture(gl.TEXTURE_2D, accumAlphaTarget);
gl.useProgram(accumProgram);
gl.uniform1i(textureLocation, 0);
gl.useProgram(drawProgram);
gl.uniform1i(accumLocation, 1);
gl.uniform1i(accumAlphaLocation, 2);
var rotationMatrix = mat4.create();
function draw() {
////////////////////
// DRAW BOXES
////////////////////
gl.bindFramebuffer(gl.FRAMEBUFFER, accumBuffer);
gl.useProgram(accumProgram);
gl.bindVertexArray(sphereArray);
for (var i = 0, len = spheres.length; i < len; ++i) {
spheres[i].rotate[1] += 0.002;
utils.xformMatrix(spheres[i].modelMatrix, spheres[i].translate, null, spheres[i].scale);
mat4.fromYRotation(rotationMatrix, spheres[i].rotate[1]);
mat4.multiply(spheres[i].modelMatrix, rotationMatrix, spheres[i].modelMatrix);
modelMatrixData.set(spheres[i].modelMatrix, i * 16);
}
gl.bindBuffer(gl.ARRAY_BUFFER, matrixBuffer);
gl.bufferSubData(gl.ARRAY_BUFFER, 0, modelMatrixData);
gl.blendFuncSeparate(gl.ONE, gl.ONE, gl.ZERO, gl.ONE_MINUS_SRC_ALPHA)
gl.clear(gl.COLOR_BUFFER_BIT);
gl.drawElementsInstanced(gl.TRIANGLES, sphere.indices.length, gl.UNSIGNED_SHORT, 0, spheres.length);
/////////
// DRAW
/////////
gl.bindFramebuffer(gl.FRAMEBUFFER, null);
gl.useProgram(drawProgram);
gl.bindVertexArray(quadArray);
gl.clear(gl.COLOR_BUFFER_BIT);
gl.blendFunc(gl.ONE, gl.ONE_MINUS_SRC_ALPHA);
gl.drawArrays(gl.TRIANGLES, 0, 6);
requestAnimationFrame(draw);
}
requestAnimationFrame(draw);
}
image.src = "img/khronos_webgl.png";
</script>
<a href="https://github.com/tsherif/webgl2examples" id="github-ribbon"><img style="position: absolute; top: 0; right: 0; border: 0;" src="https://camo.githubusercontent.com/365986a132ccd6a44c23a9169022c0b5c890c387/68747470733a2f2f73332e616d617a6f6e6177732e636f6d2f6769746875622f726962626f6e732f666f726b6d655f72696768745f7265645f6161303030302e706e67" alt="Fork me on GitHub" data-canonical-src="https://s3.amazonaws.com/github/ribbons/forkme_right_red_aa0000.png"></a>
</body>
</html>