【Blog怎么玩】学长教你给自己的博客加上雪花飘落效果——源自YJLAugus博客园

https://www.cnblogs.com/yjlaugus/p/8157414.html

全文来自于YJLAugus的博客，点击既可以查看原博文。本文全文摘抄，只添了两张图

前言

今天是2019的最后一天，首先祝福大家新年快乐，能在自己新的一年里开心快乐，幸福~。转眼间，又到了白雪飘飞的冬季，相信好多地方都下雪了吧~，突发奇想，给自己博客加上了雪花飘落效果。当然了，有写的不好的地方，大家打我就好~~

效果预览

http://www.cnblogs.com/yjlblog/ 

食用方法

• 添加js文件

（1）前提是开通了权限哦，然后把 xue.js文件上传到自己博客中；

（2）创建画布(放在页尾)；

<div class="Snow">
    <canvas id="Snow"></canvas>
</div>

• 引入js文件(放在页尾)；

<script src="https://files.cnblogs.com/files/yjlblog/xue.js"></script>

• js文件：在本地新建一个文本文件TXT，粘贴代码后，CTRL+S保存，重命名为xue.js

(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"), //画布ID，与上一步创建的画布对应
        ctx = canvas.getContext("2d"),
        flakeCount = 200,  //雪花数量，数值越大雪花数量越多
        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,  //雪花距离鼠标指针的最小值，小于这个距离的雪花将受到鼠标的排斥
                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 + ")";  //雪花颜色
            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;  //加号后面的值，雪花大小，为基准值，数值越大雪花越大
        flake.speed = (Math.random() * 1) + 0.5;  //加号后面的值，雪花速度，为基准值，数值越大雪花速度越快
        flake.velY = flake.speed;
        flake.velX = 0;
        flake.opacity = (Math.random() * 0.5) + 0.3;  //加号后面的值，为基准值，范围0~1
    }

    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,  //加号后面的值，雪花大小，为基准值，数值越大雪花越大
                speed = (Math.random() * 1) + 0.5,  //加号后面的值，雪花速度，为基准值，数值越大雪花速度越快
                opacity = (Math.random() * 0.5) + 0.3;  //加号后面的值，为基准值，范围0~1

            flakes.push({
                speed: speed,
                velY: speed,
                velX: 0,
                x: x,
                y: y,
                size: size,
                stepSize: (Math.random()) / 30 * 1,  //乘号后面的值，雪花横移幅度，为基准值，数值越大雪花横移幅度越大，0为竖直下落
                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();
})();

• 添加样式（自定义css，背景颜色可以自己改变）；

#Snow{
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 99999;
    background: rgba(125,137,95,0.1);
    pointer-events: none;
}