Created
January 1, 2018 13:11
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<!DOCTYPE html> | |
<html> | |
<head> | |
<title>Fireworks</title> | |
</head> | |
<body> | |
<script> | |
const SCRW = 800; | |
const SCRH = 800; | |
const TAU = 2 * Math.PI; | |
const canvas = document.createElement('canvas'); | |
canvas.width = SCRW; | |
canvas.height = SCRH; | |
document.body.appendChild(canvas); | |
const ctx = canvas.getContext('2d'); | |
const particles = []; | |
class Particle { | |
constructor(color, x, y, dx, dy) { | |
this.color = color; | |
this.x = x; | |
this.y = y; | |
this.dx = dx || 0; | |
this.dy = dy || 0; | |
} | |
} | |
function frand(a, b) { | |
return a + (b - a) * Math.random(); | |
} | |
function irand(a, b) { | |
return a + Math.floor((b - a) * Math.random()); | |
} | |
function firework(x, y) { | |
const n = irand(100, 120); | |
const color = `hsla(${frand(0, 360)}, 50%, 50%, 1)`; | |
for (var i = 0; i < n; ++i) { | |
const a = frand(0, TAU); | |
const v = frand(1, 10); | |
particles.push(new Particle( | |
color, | |
x, y, | |
v * Math.cos(a), | |
v * Math.sin(a) | |
)); | |
} | |
} | |
function simulate() { | |
for (let particle of particles) { | |
particle.x += particle.dx; | |
particle.y += particle.dy; | |
particle.dy += 0.5; | |
} | |
} | |
function draw() { | |
for (let particle of particles) { | |
ctx.fillStyle = particle.color; | |
ctx.fillRect(particle.x, particle.y, 2, 2); | |
} | |
} | |
function clean() { | |
ctx.fillStyle = 'black'; | |
ctx.fillRect(0, 0, SCRW, SCRH); | |
} | |
var tick = 0; | |
function loop(n) { | |
clean(); | |
simulate(); | |
draw(); | |
requestAnimationFrame(loop); | |
if (tick % 20 == 0) { | |
firework(irand(0, SCRW), irand(0, SCRH)); | |
} | |
tick += 1; | |
} | |
requestAnimationFrame(loop); | |
// setTimeout(() => window.location.reload(), 5000); | |
</script> | |
</body> | |
</html> |
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