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大半夜睡不着，来个雪花动画

2021-08-21 03:31:06 作者：互联网

效果：

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }
    </style>
</head>
<body>
<canvas id="canvas" style="border: 1px solid; background-color: #000000"></canvas>
<script>
    const cvs = document.getElementById('canvas');
    const ctx = cvs.getContext('2d');
    // 初始化宽高
    const screenSize = {width: window.screen.width, height: window.screen.height}
    cvs.setAttribute('width', screenSize.width);
    cvs.setAttribute('height', screenSize.height);

    // 随机一个坐标点
    function randomPos() {
        const x = Math.ceil(Math.random() * screenSize.width);
        const y = Math.ceil(Math.random() * screenSize.height);
        return {x, y}
    }


    function randomSnow() {
        const p = randomPos();
        const r = Math.floor(Math.random() * 3);
        const dis = Math.ceil(Math.random() * 4);
        const blur = 5 + Math.ceil(Math.random() * 5);
        proSnow(p, r, blur);
        return {p: p, r: r, dis: dis, blur: blur};
    }

    function proSnow(p, r, blur) {
        ctx.beginPath();
        ctx.arc(p.x, p.y, r, 0, Math.PI * 2 * 180);
        ctx.strokeStyle = '#FFF';
        ctx.fillStyle = '#FFF';
        ctx.stroke();
        ctx.fill();
        ctx.shadowBlur = blur;
        ctx.shadowColor = "#FFF";
        ctx.closePath();
    }

    // 随机生产雪花
    const snows = [];
    for (let i = 0; i < 500; i++) {
        snows.push(randomSnow());
    }

    // 让雪花飘起来
    setInterval(() => {
        startSnow();
    }, 60)

    function startSnow() {
        ctx.clearRect(0, 0, screenSize.width, screenSize.height);
        for (const snow of snows) {
            snow.p.y = snow.p.y + snow.dis;
            if (snow.p.y > screenSize.height) {
                snow.p.y = -10;
                snow.dis = Math.ceil(Math.random() * 4);
            }
            proSnow(snow.p, snow.r, snow.blur);
        }
    }

    // const animationFrame = window.requestAnimationFrame || window.webkitRequestAnimationFrame;
    // window.requestAnimationFrame(startSnow)
</script>
</body>
</html>

标签：动画,大半夜,const,来个,ctx,snow,screenSize,blur,Math
来源： https://www.cnblogs.com/hello-dummy/p/15168732.html