const rand = (m, M) => Math.random() * (M - m) + m,
PI = Math.PI,
TAU = PI * 2,
width = window.innerWidth,
height = window.innerHeight,
ctx = document.getElementById('cvs').getContext('2d'),
items = [],
Item = function() {
this.h = 32;
this.w = 32;
this.IMG = new Image();
this.IMG.src = 'http://stackoverflow.com/favicon.ico';
this.start();
return this;
};
Item.prototype.start = function() {
this.x = rand(0, width - this.w / 2);
this.y = rand(0, height);
this.angle = rand(0, TAU);
this.speed = rand(0.1, 0.5);
}
Item.prototype.move = function() {
// Manipulate properties
if (this.y > height + this.h) { // if is below bottom
this.start();
this.y = -this.h; // restart from top
}
this.y += this.speed / 0.1;
this.angle += this.speed;
this.angle %= TAU;
// Manipulate context
ctx.save(); // save context
ctx.translate(this.x, this.y); // move to point
ctx.rotate(this.angle); // rotate around that point
ctx.drawImage(this.IMG, -this.w/2, -this.h/2);
ctx.restore(); // restore to initial coordinates
};
// Setup canvas
ctx.canvas.width = width;
ctx.canvas.height = height;
// Create falling Icons
for (var i = 0; i < 100; i++) items.push(new Item());
// Animation loop
(function loop() {
ctx.clearRect(0, 0, width, height);
items.forEach(Item => Item.move());
requestAnimationFrame(loop);
}());
body {margin: 0;}
canvas {display: block;}
<canvas id="cvs"></canvas>
