JavaScript canvas实现跟随鼠标移动小球

冷不防 2022-10-29 07:51 209阅读 0赞

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

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<!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>