superYan520.github.io/index.html at master · superYan520/superYan520.github.io · GitHub

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<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <style>
        * {
            margin: 0;
            padding: 0;
        }
        body{
            background-color: black;
        }

        canvas {
            border: 1px solid gray;
        }
    </style>
    <title>document</title>
</head>

<body>
    <canvas id="canvas" width="600" height="400"></canvas>
</body>
<script>
    var canvas = document.querySelector('canvas');
    var ctx = canvas.getContext('2d');

    // 圆心
    var x = 300;
    var y = 200;
    // 速度;
    var xSpeed = 8;
    var ySpeed = 2;
    // 函数
    // function color() {
    //     var arr=[]

    //     var colorD=

    // }
        // var i =0;

    function draw() {
        // 清理画布
        // ctx.clearRect(0, 0, canvas.width, canvas.height);
        var color1=Math.ceil(Math.random()*255);
        var color2=Math.ceil(Math.random()*255);
        var color3=Math.ceil(Math.random()*255);
        ctx.fillStyle="rgba(255,255,255, .1)";
        ctx.fillRect(0,0,canvas.width,canvas.height);
        // if (i>=2) {
        //     return;
        // }
        x += xSpeed;
        y += ySpeed;

        if (x<=20||x>=canvas.width-20) {
            xSpeed=-xSpeed;

        };
        if (y<=20||y>=canvas.height-20) {
            ySpeed=-ySpeed;
        }

        ctx.beginPath();
        // 画圆
        ctx.arc(x, y, 25, 0, 2 * Math.PI);
        ctx.fillStyle = "rgba("+color1+","+color2+","+color3+", .3)";
        ctx.fill();


        // i++;


    }

    setInterval(draw, 16.7)
</script>

</html>