Created
May 16, 2016 14:45
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Example of smoke shader in Pixi.js
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<!DOCTYPE html> | |
<html> | |
<head> | |
<title>PixiJS Shaders</title> | |
<style type="text/css"> | |
body { | |
margin: 0; | |
overflow: hidden; | |
} | |
</style> | |
</head> | |
<body> | |
<script type="text/javascript" src="pixi.min.js"></script> | |
<script id="fragShader" type="shader-code"> | |
precision mediump float; | |
uniform vec2 resolution; | |
uniform float time; | |
uniform float alpha; | |
uniform vec2 speed; | |
uniform float shift; | |
float rand(vec2 n) { | |
//This is just a compounded expression to simulate a random number based on a seed given as n | |
return fract(cos(dot(n, vec2(12.9898, 4.1414))) * 43758.5453); | |
} | |
float noise(vec2 n) { | |
//Uses the rand function to generate noise | |
const vec2 d = vec2(0.0, 1.0); | |
vec2 b = floor(n), f = smoothstep(vec2(0.0), vec2(1.0), fract(n)); | |
return mix(mix(rand(b), rand(b + d.yx), f.x), mix(rand(b + d.xy), rand(b + d.yy), f.x), f.y); | |
} | |
float fbm(vec2 n) { | |
//fbm stands for "Fractal Brownian Motion" https://en.wikipedia.org/wiki/Fractional_Brownian_motion | |
float total = 0.0, amplitude = 1.0; | |
for (int i = 0; i < 4; i++) { | |
total += noise(n) * amplitude; | |
n += n; | |
amplitude *= 0.5; | |
} | |
return total; | |
} | |
void main() { | |
//This is where our shader comes together | |
const vec3 c1 = vec3(126.0/255.0, 0.0/255.0, 97.0/255.0); | |
const vec3 c2 = vec3(173.0/255.0, 0.0/255.0, 161.4/255.0); | |
const vec3 c3 = vec3(0.2, 0.0, 0.0); | |
const vec3 c4 = vec3(164.0/255.0, 1.0/255.0, 214.4/255.0); | |
const vec3 c5 = vec3(0.1); | |
const vec3 c6 = vec3(0.9); | |
//This is how "packed" the smoke is in our area. Try changing 8.0 to 1.0, or something else | |
vec2 p = gl_FragCoord.xy * 8.0 / resolution.xx; | |
//The fbm function takes p as its seed (so each pixel looks different) and time (so it shifts over time) | |
float q = fbm(p - time * 0.1); | |
vec2 r = vec2(fbm(p + q + time * speed.x - p.x - p.y), fbm(p + q - time * speed.y)); | |
vec3 c = mix(c1, c2, fbm(p + r)) + mix(c3, c4, r.x) - mix(c5, c6, r.y); | |
float grad = gl_FragCoord.y / resolution.y; | |
gl_FragColor = vec4(c * cos(shift * gl_FragCoord.y / resolution.y), 1.0); | |
gl_FragColor.xyz *= 1.0-grad; | |
} | |
</script> | |
<script type="text/javascript"> | |
//Adapted from: http://codepen.io/davidhartley/pen/seEki?editors=0010 | |
var width = window.innerWidth; | |
var height = window.innerHeight; | |
var renderer = new PIXI.autoDetectRenderer(width, height);//Chooses either WebGL if supported or falls back to Canvas rendering | |
document.body.appendChild(renderer.view);//Add the render view object into the page | |
var stage = new PIXI.Container();//The stage is the root container that will hold everything in our scene | |
// smoke shader | |
var uniforms = {}; | |
uniforms.resolution = { type: 'v2', value: { x: width, y: height}}; | |
uniforms.alpha = { type: '1f', value: 1.0}; | |
uniforms.shift = { type: '1f', value: 1.6}; | |
uniforms.time = {type: '1f',value: 0}; | |
uniforms.speed = {type: 'v2', value: {x: 0.7, y: 0.4}}; | |
var shaderCode = document.getElementById( 'fragShader' ).innerHTML | |
var smokeShader = new PIXI.AbstractFilter('',shaderCode, uniforms); | |
var bg = PIXI.Sprite.fromImage("http://www.goodboydigital.com/pixijs/pixi_v3_github-pad.png"); | |
bg.width = width; | |
bg.height = height; | |
bg.filters = [smokeShader] | |
stage.addChild(bg); | |
var logo = PIXI.Sprite.fromImage("http://www.goodboydigital.com/pixijs/pixi_v3_github-pad.png"); | |
logo.x = width / 2; | |
logo.y = height / 2; | |
logo.anchor.set(0.5); | |
logo.blendMode = PIXI.BLEND_MODES.ADD; | |
stage.addChild(logo) | |
animate() | |
var count = 0 | |
function animate() { | |
// start the timer for the next animation loop | |
requestAnimationFrame(animate); | |
count+=0.01 | |
smokeShader.uniforms.time.value = count; | |
// this is the main render call that makes pixi draw your container and its children. | |
renderer.render(stage); | |
} | |
</script> | |
</body> | |
</html> |
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