”圣诞节“—–好看的雪花效果有没有？ – Angelべ桀瑞

!function($){

var defaults = {
speed: 0,
interaction: true,
size: 2,
count: 200,
opacity: 0,
color: “#ffffff”,
windPower: 0,
image: false
};

$.fn.let_it_snow = function(options){
var settings = $.extend({}, defaults, options),
el = $(this),
flakes = [],
canvas = el.get(0),
ctx = canvas.getContext(“2d”),
flakeCount = settings.count,
mX = -100,
mY = -100;

canvas.width = window.innerWidth;
canvas.height = window.innerHeight;

(function() {
var requestAnimationFrame = window.requestAnimationFrame || window.mozRequestAnimationFrame || window.webkitRequestAnimationFrame || window.msRequestAnimationFrame ||
function(callback) {
window.setTimeout(callback, 1000 / 60);
};
window.requestAnimationFrame = requestAnimationFrame;
})();

function snow() {
ctx.clearRect(0, 0, canvas.width, canvas.height);

for (var i = 0; i < flakeCount; i++) {
var flake = flakes[i],
x = mX,
y = mY,
minDist = 100,
x2 = flake.x,
y2 = flake.y;

var dist = Math.sqrt((x2 – x) * (x2 – x) + (y2 – y) * (y2 – y)),
dx = x2 – x,
dy = y2 – y;

if (dist < minDist) {
var force = minDist / (dist * dist),
xcomp = (x – x2) / dist,
ycomp = (y – y2) / dist,
deltaV = force / 2;

flake.velX -= deltaV * xcomp;
flake.velY -= deltaV * ycomp;

} else {
flake.velX *= .98;
if (flake.velY <= flake.speed) {
flake.velY = flake.speed
}

switch (settings.windPower) {
case false:
flake.velX += Math.cos(flake.step += .05) * flake.stepSize;
break;

case 0:
flake.velX += Math.cos(flake.step += .05) * flake.stepSize;
break;

default:
flake.velX += 0.01 + (settings.windPower/100);
}
}

var s = settings.color;
var patt = /^#([da-fA-F]{2})([da-fA-F]{2})([da-fA-F]{2})$/;
var matches = patt.exec(s);
var rgb = parseInt(matches[1], 16)+”,”+parseInt(matches[2], 16)+”,”+parseInt(matches[3], 16);

flake.y += flake.velY;
flake.x += flake.velX;

if (flake.y >= canvas.height || flake.y <= 0) {
reset(flake);
}

if (flake.x >= canvas.width || flake.x <= 0) {
reset(flake);
}
if (settings.image == false) {
ctx.fillStyle = “rgba(” + rgb + “,” + flake.opacity + “)”
ctx.beginPath();
ctx.arc(flake.x, flake.y, flake.size, 0, Math.PI * 2);
ctx.fill();
} else {

ctx.drawImage($(“img#lis_flake”).get(0), flake.x, flake.y, flake.size * 2, flake.size * 2);
}

}
requestAnimationFrame(snow);
};

function reset(flake) {

if (settings.windPower == false || settings.windPower == 0) {
flake.x = Math.floor(Math.random() * canvas.width);
flake.y = 0;
} else {
if (settings.windPower > 0) {
var xarray = Array(Math.floor(Math.random() * canvas.width), 0);
var yarray = Array(0, Math.floor(Math.random() * canvas.height))
var allarray = Array(xarray, yarray)

var selected_array = allarray[Math.floor(Math.random()*allarray.length)];

flake.x = selected_array[0];
flake.y = selected_array[1];
} else {
var xarray = Array(Math.floor(Math.random() * canvas.width),0);
var yarray = Array(canvas.width, Math.floor(Math.random() * canvas.height))
var allarray = Array(xarray, yarray)

var selected_array = allarray[Math.floor(Math.random()*allarray.length)];

flake.x = selected_array[0];
flake.y = selected_array[1];
}
}

flake.size = (Math.random() * 3) + settings.size;
flake.speed = (Math.random() * 1) + settings.speed;
flake.velY = flake.speed;
flake.velX = 0;
flake.opacity = (Math.random() * 0.5) + settings.opacity;
}
function init() {
for (var i = 0; i < flakeCount; i++) {
var x = Math.floor(Math.random() * canvas.width),
y = Math.floor(Math.random() * canvas.height),
size = (Math.random() * 3) + settings.size,
speed = (Math.random() * 1) + settings.speed,
opacity = (Math.random() * 0.5) + settings.opacity;

flakes.push({
speed: speed,
velY: speed,
velX: 0,
x: x,
y: y,
size: size,
stepSize: (Math.random()) / 30,
step: 0,
angle: 180,
opacity: opacity
});
}

snow();
}

if (settings.image != false) {
$(“<img src='”+settings.image+”‘ style=’display: none’ id=’lis_flake’>”).prependTo(“body”)
}

init();

$(window).resize(function() {
if(this.resizeTO) clearTimeout(this.resizeTO);
this.resizeTO = setTimeout(function() {
el2 = el.clone();
el2.insertAfter(el);
el.remove();

el2.let_it_snow(settings);
}, 200);
});

if (settings.interaction == true) {
canvas.addEventListener(“mousemove”, function(e) {
mX = e.clientX,
mY = e.clientY
});
}
}
}(window.jQuery);