WordPress-OneNav主题美化：给页面添加下雪花的效果

代码可放到全局内容页尾（全局 : html > body ( footer_js_after )）或者某个页面

<canvas id="Snow" style="position: fixed;top: 0;left: 0;width: 100%;height: 100%;z-index: 99999;background: rgba(125,137,95,0.1);pointer-events: none;"></canvas>
<script>
if(true){
(function() {
var requestAnimationFrame = window.requestAnimationFrame || window.mozRequestAnimationFrame || window.webkitRequestAnimationFrame || window.msRequestAnimationFrame ||
function(callback) {
window.setTimeout(callback, 1000 / 60);
};
window.requestAnimationFrame = requestAnimationFrame;
})();

(function() {
var flakes = [],
canvas = document.getElementById("Snow"),
ctx = canvas.getContext("2d"),
flakeCount = 200,
mX = -100,
mY = -100;

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

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 = 150,
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 }
flake.velX += Math.cos(flake.step += .05) * flake.stepSize;
}

ctx.fillStyle = "rgba(255,255,255," + flake.opacity + ")";
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);
}

ctx.beginPath();
ctx.arc(flake.x, flake.y, flake.size, 0, Math.PI * 2);
ctx.fill();
}
requestAnimationFrame(snow);
};

function reset(flake) {
flake.x = Math.floor(Math.random() * canvas.width);
flake.y = 0;
flake.size = (Math.random() * 3) + 2;
flake.speed = (Math.random() * 1) + 0.5;
flake.velY = flake.speed;
flake.velX = 0;
flake.opacity = (Math.random() * 0.5) + 0.3;
}

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) + 2,
speed = (Math.random() * 1) + 0.5,
opacity = (Math.random() * 0.5) + 0.3;

flakes.push({
speed: speed,
velY: speed,
velX: 0,
x: x,
y: y,
size: size,
stepSize: (Math.random()) / 30 * 1,
step: 0,
angle: 180,
opacity: opacity });
}

snow();
};

document.addEventListener("mousemove", function(e) {
mX = e.clientX,
mY = e.clientY });
window.addEventListener("resize", function() {
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
});
init();
})();
}
</script>