mirror of https://github.com/ENSL/ensl_gathers.git
89 lines
2.1 KiB
JavaScript
89 lines
2.1 KiB
JavaScript
var SnowMachine = function () {
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this.canvas = document.getElementById("canvas");
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this.ctx = this.canvas.getContext("2d");
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this.mp = 25;
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this.angle = 0;
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window.addEventListener('resize', this.resizeCanvas, false);
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this.resizeCanvas();
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};
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SnowMachine.prototype.resizeCanvas = function () {
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var canvas = this.canvas;
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this.W = window.innerWidth;
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this.H = window.innerHeight;
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canvas.width = this.W;
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canvas.height = this.H;
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};
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SnowMachine.prototype.initCanvas = function () {
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this.particles = [];
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for(var i = 0; i < this.mp; i++) {
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this.particles.push({
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x: Math.random() * this.W,
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y: Math.random() * this.H,
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r: Math.random() * 4 + 1,
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d: Math.random() * this.mp
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});
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}
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};
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SnowMachine.prototype.draw = function () {
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var ctx = this.ctx;
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var W = this.W;
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var H = this.H;
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ctx.clearRect(0, 0, W, H);
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ctx.fillStyle = "rgba(255, 255, 255, 0.8)";
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ctx.beginPath();
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for(var i = 0; i < this.mp; i++) {
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var p = this.particles[i];
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ctx.moveTo(p.x, p.y);
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ctx.arc(p.x, p.y, p.r, 0, Math.PI*2, true);
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}
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ctx.fill();
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this.update();
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};
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SnowMachine.prototype.update = function () {
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var particles = this.particles
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var W = this.W;
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var H = this.H;
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var mp = this.mp;
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this.angle += 0.01;
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for (var i = 0; i < mp; i++) {
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var p = particles[i];
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p.y += Math.cos(this.angle+p.d) + 1 + p.r/2;
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p.x += Math.sin(this.angle) * 2;
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//Sending flakes back from the top when it exits
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//Lets make it a bit more organic and let flakes enter from the left and right also.
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if(p.x > W+5 || p.x < -5 || p.y > H) {
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if(i%3 > 0) {
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//66.67% of the flakes
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particles[i] = {x: Math.random()*W, y: -10, r: p.r, d: p.d};
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} else {
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//If the flake is exitting from the right
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if(Math.sin(this.angle) > 0) {
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//Enter from the left
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particles[i] = {x: -5, y: Math.random()*H, r: p.r, d: p.d};
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} else {
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//Enter from the right
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particles[i] = {x: W+5, y: Math.random()*H, r: p.r, d: p.d};
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}
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}
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}
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}
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};
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SnowMachine.prototype.start = function () {
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this.initCanvas();
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this.timer = setInterval(this.draw.bind(this), 33);
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};
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SnowMachine.prototype.stop = function () {
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if (this.timer) {
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window.clearInterval(this.timer);
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this.timer = null;
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}
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};
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