Эффект метели на JS

Пример:

HTML:

<canvas id="bg-img"></canvas>

1	<canvas id="bg-img"></canvas>

CSS:

#bg-img {
	background: url(background.jpg);
	background-position: center center;
	background-size: cover;
	width: 100%;
}

#bg-img {

background: url(background.jpg);

background-position: center center;

background-size: cover;

width: 100%;

}

JS:

Подключаем библиотеку TweenMax.min.js и скрипт самой анимации:

var n = 999, //кол-во снежинок
speed = 3, // скорость
wind = 500, // наклон снежинок
windVariance = 1.5, // отклонение снежинок, 1 = без отклонения
c = document.getElementById("bg-img"),
ctx = c.getContext("2d"),
cw = (c.width = c.offsetWidth);
ch = (c.height = 500);
img = new Image(64,64),
particles = [],
particleNumber = 0,
Particle = function(index) {
	this.size = rand(5, 10);
	this.dur = (15-this.size)/speed;
	this.alpha = rand(0.25, 0.75);
	if (index<n/100) {
        this.size = rand(150,200);
        this.dur = this.dur/4;
        this.alpha = this.alpha/3.3;
		} else if (index<n/10) {
        this.size = rand(19,33);
        this.dur = this.dur/2.5;
        this.alpha = this.alpha/1.5;
	}
	var rot = -rand(3,5); 
	if (index%4==0) rot= -rot;
	this.draw = function() {
        ctx.translate( this.x, this.y );
        ctx.rotate(rot*this.progress);
        ctx.globalAlpha = this.alpha;
        ctx.drawImage(img, -this.size/2, -this.size/2, this.size, this.size);
        ctx.rotate(-rot*this.progress);
        ctx.translate( -this.x, -this.y );
	}
};
function setParticle(p) {
	particleNumber++;
	var _tl = new TimelineMax()
	.fromTo(p, p.dur, {
		x:rand(-Math.abs(wind), (cw + Math.abs(wind))),
		y:-p.size,
		progress:0
		},{
		x:'+='+String( rand(wind/windVariance, wind*windVariance)), 
		y:ch+p.size,
		progress:1,              
		ease:Power0.easeNone,
		onComplete:function(){ setParticle(p); }
	});
	if (particleNumber<n) _tl.seek(p.dur*rand());
}
for (var i=0; i<n; i++) {
    particles.push(new Particle(i));
    setParticle(particles[i]);      
}
TweenMax.ticker.addEventListener("tick", function(){
	ctx.clearRect(0, 0, cw, ch);
	for (var i=0; i<n; i++) {
		particles[i].draw();
	}
});
window.addEventListener('resize', function() {
	particleNumber = 0;  
    cw = (c.width = c.offsetWidth);
    ch = (c.height = 500);
	for (var i=0; i<n; i++) {
		TweenMax.killTweensOf(particles[i]);
		setParticle(particles[i]);
	}
});
function rand(min=0, max=1) {
	return min + (max-min)*Math.random();
}
img.src = "data:image/png;base64,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";

var n = 999, //кол-во снежинок

speed = 3, // скорость

wind = 500, // наклон снежинок

windVariance = 1.5, // отклонение снежинок, 1 = без отклонения

c = document.getElementById("bg-img"),

ctx = c.getContext("2d"),

cw = (c.width = c.offsetWidth);

ch = (c.height = 500);

img = new Image(64,64),

particles = [],

particleNumber = 0,

Particle = function(index) {

this.size = rand(5, 10);

this.dur = (15-this.size)/speed;

this.alpha = rand(0.25, 0.75);

if (index<n/100) {

this.size = rand(150,200);

this.dur = this.dur/4;

this.alpha = this.alpha/3.3;

} else if (index<n/10) {

this.size = rand(19,33);

this.dur = this.dur/2.5;

this.alpha = this.alpha/1.5;

}

var rot = -rand(3,5);

if (index%4==0) rot= -rot;

this.draw = function() {

ctx.translate( this.x, this.y );

ctx.rotate(rot*this.progress);

ctx.globalAlpha = this.alpha;

ctx.drawImage(img, -this.size/2, -this.size/2, this.size, this.size);

ctx.rotate(-rot*this.progress);

ctx.translate( -this.x, -this.y );

}

};

function setParticle(p) {

particleNumber++;

var _tl = new TimelineMax()

.fromTo(p, p.dur, {

x:rand(-Math.abs(wind), (cw + Math.abs(wind))),

y:-p.size,

progress:0

},{

x:'+='+String( rand(wind/windVariance, wind*windVariance)),

y:ch+p.size,

progress:1,

ease:Power0.easeNone,

onComplete:function(){ setParticle(p); }

});

if (particleNumber<n) _tl.seek(p.dur*rand());

}

for (var i=0; i<n; i++) {

particles.push(new Particle(i));

setParticle(particles[i]);

}

TweenMax.ticker.addEventListener("tick", function(){

ctx.clearRect(0, 0, cw, ch);

for (var i=0; i<n; i++) {

particles[i].draw();

}

});

window.addEventListener('resize', function() {

particleNumber = 0;

cw = (c.width = c.offsetWidth);

ch = (c.height = 500);

for (var i=0; i<n; i++) {

TweenMax.killTweensOf(particles[i]);

setParticle(particles[i]);

}

});

function rand(min=0, max=1) {

return min + (max-min)*Math.random();

}

img.src = "data:image/png;base64,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";

Где:

n - Кол-во снежинок

speed - Их скорость.

wind - Ветер (наклон снежинок)

windVariance - Отклонение снежинок, 1 = без отклонения.

ch - Высота блока

cw - Ширина блока.

img.src - Снежинка в base64

Фон канваса задается через CSS

Заменив изображение img.src, с неба могут падать смайлики, наковальни и другие предметы.

Найдено на codepen.io у пользователя Tom Miller
Автор фотографии cgcowboy

Пример:

HTML:

CSS:

JS:

Где:

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