JavaScript canvas实现跟随鼠标移动小球

网络编程 2024/12/27 佚名

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本文实例为大家分享了js跟随鼠标移动小球的具体代码，供大家参考，具体内容如下

<!DOCTYPE html>
<html>
 <head>
 <meta charset="utf-8">
 <title></title>
 <style>
 canvas{
 border: 1px solid #000;
 }
 </style>
 </head>
 <body>
 <canvas id="mycanvas" width="1500" height="800"></canvas>
 <script>
 // 创建画布
 var canvas = document.getElementById('mycanvas');
 var ctx = canvas.getContext('2d');
 // 球类
 function Ball(x, y) {
 this.x = x;
 this.y = y;
 // 初始半径
 this.r = parseInt(Math.random() * 50) + 10;
 this.step = parseInt(Math.random() * 5) + 0.1;
 // 设置随机颜色
 this.color = getRandom();
 // 设置随机方向
 this.dx = parseInt(Math.random() * 10) - 5;
 this.dy = parseInt(Math.random() * 10) - 5;
 // 将自身对象装入数组中
 ballArr.push(this);
 }
 // 在数组中删除对象
 Ball.prototype.remove = function() {
 for (var i = 0; i < ballArr.length; i++) {
 if (ballArr[i] == this) {
 ballArr.splice(i, 1);
 }
 }
 }
 // 更新数据
 Ball.prototype.update = function() {
 // 更新数据
 this.x += this.dx;
 this.y += this.dy;
 this.r -= this.step;
 // 清除数组中的小球
 if (this.r <= 0) {
 this.remove();
 }
 // 如果超出边界，小球继续运动
 if (this.x < 0) {
 this.x = 1500;
 this.color = getRandom();
 }
 else if (this.x > 1500) {
 this.x = 0;
 this.color = getRandom();
 }
 else if (this.y < 0) {
 this.y = 800;
 this.color = getRandom();
 }
 else if (this.y > 800) {
 this.y = 0;
 this.color = getRandom();
 }
 }
 // 渲染小球
 Ball.prototype.render = function() {
 ctx.beginPath();
 ctx.arc(this.x, this.y, this.r, 0, Math.PI * 2, false);
 ctx.fillStyle = this.color;
 ctx.fill();
 }
 // canvas 画布DOM2事件
 canvas.addEventListener("mousemove", function(event) {
 new Ball(event.offsetX, event.offsetY);
 });
 var ballArr = [];
 // 定时器进行动画渲染和更新
 setInterval(function() {
 // 动画逻辑 
 // 清屏-更新-渲染
 ctx.clearRect(0, 0, canvas.width, canvas.height);
 // 小球的更新和渲染
 for (var i = 0; i < ballArr.length; i++) {
 ballArr[i].update();
 if (ballArr[i]) {
 ballArr[i].render();
 }
 }
 }, 30);
 // 随机颜色
 function getRandom() {
 var allType = "0,1,2,3,4,5,6,7,8,9,a,b,c,d,e,f";
 var allTypeArr = allType.split(",");
 var color = "#";
 // 拼接颜色字符串
 for (var i = 0; i < 6; i++) {
 var random = parseInt(Math.random() * allTypeArr.length);
 color += allTypeArr[random];
 }
 return color;
 }
 </script>
 </body>
</html>

效果