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3.01-QCM_MuscuMaths/Website/js/confetti.js

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let W = window.innerWidth;
let H = document.getElementById('confetti').clientHeight;
const canvas = document.getElementById('confetti');
const context = canvas.getContext("2d");
const maxConfettis = 25;
const particles = [];
const possibleColors = [
"#ff7336",
"#f9e038",
"#02cca4",
"#383082",
"#fed3f5",
"#b1245a",
"#f2733f"
];
function randomFromTo(from, to) {
return Math.floor(Math.random() * (to - from + 1) + from);
}
function confettiParticle() {
this.x = Math.random() * W; // x
this.y = Math.random() * H - H; // y
this.r = randomFromTo(11, 33); // radius
this.d = Math.random() * maxConfettis + 11;
this.color =
possibleColors[Math.floor(Math.random() * possibleColors.length)];
this.tilt = Math.floor(Math.random() * 33) - 11;
this.tiltAngleIncremental = Math.random() * 0.07 + 0.05;
this.tiltAngle = 0;
this.draw = function() {
context.beginPath();
context.lineWidth = this.r / 2;
context.strokeStyle = this.color;
context.moveTo(this.x + this.tilt + this.r / 3, this.y);
context.lineTo(this.x + this.tilt, this.y + this.tilt + this.r / 5);
return context.stroke();
};
}
function Draw() {
const results = [];
// Magical recursive functional love
requestAnimationFrame(Draw);
context.clearRect(0, 0, W, window.innerHeight);
for (var i = 0; i < maxConfettis; i++) {
results.push(particles[i].draw());
}
let particle = {};
let remainingFlakes = 0;
for (var i = 0; i < maxConfettis; i++) {
particle = particles[i];
particle.tiltAngle += particle.tiltAngleIncremental;
particle.y += (Math.cos(particle.d) + 3 + particle.r / 2) / 2;
particle.tilt = Math.sin(particle.tiltAngle - i / 3) * 15;
if (particle.y <= H) remainingFlakes++;
// If a confetti has fluttered out of view,
// bring it back to above the viewport and let if re-fall.
if (particle.x > W + 30 || particle.x < -30 || particle.y > H) {
particle.x = Math.random() * W;
particle.y = -30;
particle.tilt = Math.floor(Math.random() * 10) - 20;
}
}
return results;
}
window.addEventListener(
"resize",
function() {
W = window.innerWidth;
H = window.innerHeight;
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
},
false
);
// Push new confetti objects to `particles[]`
for (var i = 0; i < maxConfettis; i++) {
particles.push(new confettiParticle());
}
// Initialize
canvas.width = W;
canvas.height = H;
Draw();