Awesome fireworks display.
Created
June 25, 2018 08:18
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Fireworks
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var rnd = Math.random, | |
flr = Math.floor; | |
let canvas = document.createElement('canvas'); | |
document.getElementsByTagName('body')[0].appendChild(canvas); | |
canvas.style.position = 'absolute'; | |
canvas.style.width = '100%'; | |
canvas.style.height = '100%'; | |
canvas.width = canvas.clientWidth; | |
canvas.height = canvas.clientHeight; | |
let ctx = canvas.getContext('2d'); | |
function rndNum(num) { | |
return rnd() * num + 1; | |
} | |
function vector(x, y) { | |
this.x = x; | |
this.y = y; | |
this.add = function(vec2) { | |
this.x = this.x + vec2.x; | |
this.y = this.y + vec2.y; | |
} | |
} | |
function particle(pos, vel) { | |
this.pos = new vector(pos.x, pos.y); | |
this.vel = vel; | |
this.dead = false; | |
this.start = 0; | |
this.update = function(time) { | |
let timeSpan = time - this.start; | |
if (timeSpan > 500) { | |
this.dead = true; | |
} | |
if (!this.dead) { | |
this.pos.add(this.vel); | |
this.vel.y = this.vel.y + gravity; | |
} | |
}; | |
this.draw = function() { | |
if (!this.dead) { | |
drawDot(this.pos.x, this.pos.y, 1); | |
} | |
} | |
} | |
function firework(x, y) { | |
this.pos = new vector(x, y); | |
this.vel = new vector(0, -rndNum(10) - 3); | |
this.color = 'hsl(' + rndNum(360) + ', 100%, 50%)' | |
this.size = 4; | |
this.dead = false; | |
this.start = 0; | |
let exParticles = [], | |
exPLen = 100; | |
let rootShow = true; | |
this.update = function(time) { | |
if (this.dead) { | |
return; | |
} | |
rootShow = this.vel.y < 0; | |
if (rootShow) { | |
this.pos.add(this.vel); | |
this.vel.y = this.vel.y + gravity; | |
} else { | |
if (exParticles.length === 0) { | |
flash = true; | |
for (let i = 0; i < exPLen; i++) { | |
exParticles.push(new particle(this.pos, new vector(-rndNum(10) + 5, -rndNum(10) + 5))); | |
exParticles[exParticles.length - 1].start = time; | |
} | |
} | |
let numOfDead = 0; | |
for (let i = 0; i < exPLen; i++) { | |
let p = exParticles[i]; | |
p.update(time); | |
if (p.dead) { | |
numOfDead++; | |
} | |
} | |
if (numOfDead === exPLen) { | |
this.dead = true; | |
} | |
} | |
} | |
this.draw = function() { | |
if (this.dead) { | |
return; | |
} | |
ctx.fillStyle = this.color; | |
if (rootShow) { | |
drawDot(this.pos.x, this.pos.y, this.size); | |
} else { | |
for (let i = 0; i < exPLen; i++) { | |
let p = exParticles[i]; | |
p.draw(); | |
} | |
} | |
} | |
} | |
function drawDot(x, y, size) { | |
ctx.beginPath(); | |
ctx.arc(x, y, size, 0, Math.PI * 2); | |
ctx.fill(); | |
ctx.closePath(); | |
} | |
var fireworks = [], | |
gravity = 0.2, | |
snapTime = 0, | |
flash = false; | |
function init() { | |
let numOfFireworks = 20; | |
for (let i = 0; i < numOfFireworks; i++) { | |
fireworks.push(new firework(rndNum(canvas.width), canvas.height)); | |
} | |
} | |
function update(time) { | |
for (let i = 0, len = fireworks.length; i < len; i++) { | |
let p = fireworks[i]; | |
p.update(time); | |
} | |
} | |
function draw(time) { | |
update(time); | |
ctx.fillStyle = 'rgba(0,0,0,0.3)'; | |
if (flash) { | |
flash = false; | |
} | |
ctx.fillRect(0, 0, canvas.width, canvas.height); | |
ctx.fillStyle = 'white'; | |
ctx.font = "30px Arial"; | |
let newTime = time - snapTime; | |
snapTime = time; | |
//ctx.fillText(newTime,10,50); | |
ctx.fillStyle = 'blue'; | |
for (let i = 0, len = fireworks.length; i < len; i++) { | |
let p = fireworks[i]; | |
if (p.dead) { | |
fireworks[i] = new firework(rndNum(canvas.width), canvas.height); | |
p = fireworks[i]; | |
p.start = time; | |
} | |
p.draw(); | |
} | |
window.requestAnimationFrame(draw); | |
} | |
window.addEventListener('resize', function() { | |
canvas.width = canvas.clientWidth; | |
canvas.height = canvas.clientHeight; | |
}); | |
init(); | |
draw(); |
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* { | |
margin: 0; | |
padding: 0; | |
} |
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