Canvas雷达显示图，动态扫描

绝地灬酷狼 2024-02-20 12:32 3阅读 0赞

做卫星项目的时候，会涉及到雷达图，用于扫描卫星，给人形象化的感觉。以下代码为canvas实现的demo，请运行查看.

### 效果图 ###

![在这里插入图片描述][21e13da2cb37442cb455170a3ffcffea.gif_pic_center]

### 源代码 ###

<!DOCTYPE html>
    <html lang="zh">
     
    <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">
        <title>radar</title>
        <style>
            canvas {
        
                margin: 20px auto;
                display: block;
            }
        </style>
    </head>
     
    <body>
        <canvas id="can" width=300 height=300></canvas>
     
        <script type="text/javascript">
            var CFG = {
        
                perDeg: 1,
            };
     
            var can = document.getElementById('can');
            var ctx = can.getContext('2d');
            var deg = 0;
            ctx.strokeStyle = 'rgba(0,255,0,1)';
     
            function init() {
        
                ctx.fillStyle = 'rgba(0,50,0,1)';
                ctx.arc(150, 150, 150, 0, 2 * Math.PI);
                ctx.fill();
                var raf = window.requestAnimationFrame(loop);
            }
     
            function loop() {
        
                deg = (deg + CFG.perDeg);
                cover();
                drawPosLine();
                drawRadar(deg);
                raf = window.requestAnimationFrame(loop);
            }
     
            function cover() {
        
                ctx.save();
                ctx.fillStyle = 'rgba(0,0,0,0.02)';
                ctx.arc(150, 150, 150, 0, 2 * Math.PI);
                ctx.fill();
                ctx.restore();
            }
     
            function drawPosLine() {
        
                ctx.beginPath();
                ctx.moveTo(150, 0);
                ctx.lineTo(150, 300);
                ctx.closePath();
                ctx.stroke();
     
                ctx.beginPath();
                ctx.moveTo(0, 150);
                ctx.lineTo(300, 150);
                ctx.closePath();
                ctx.stroke();
     
                ctx.moveTo(150, 150);
                ctx.beginPath();
                ctx.arc(150, 150, 100, 0 * Math.PI, 2 * Math.PI);
                ctx.closePath();
                ctx.stroke();
     
                ctx.moveTo(150, 150);
                ctx.beginPath();
                ctx.arc(150, 150, 50, 0 * Math.PI, 2 * Math.PI);
                ctx.closePath();
                ctx.stroke();
            }
     
            function drawRadar(iDeg) {
        
                ctx.fillStyle = 'rgba(0,200,0,.7)';
                ctx.beginPath();
                ctx.moveTo(150, 150);
                ctx.arc(150, 150, 150, (-2 * CFG.perDeg + iDeg) / 180 * Math.PI, (0 + iDeg) / 180 * Math.PI);
                ctx.closePath();
                ctx.fill();
            }
     
            init();
        </script>
    </body>
     
    </html>

[21e13da2cb37442cb455170a3ffcffea.gif_pic_center]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/20/d35ed888ac604b3c8ea5c4bc32b31147.png