欲观看动态效果请点此下载代码并用Chrome或者Firefox打开。
图例：
![[Canvas]更多的球](https://img.zhankr.net/5rwjah1aaez149611.png)
代码：
<!DOCTYPE html><html lang="utf-8"><meta http-equiv="Content-Type" content="text/html; charset=utf-8"/><head> <title>更多碰撞球 19.3.4 8:53 by:逆火狂飙 horn19782016@163.com</title> <style> #canvas{ background:#ffffff; cursor:pointer; margin-left:10px; margin-top:10px; -webkit-box-shadow:3px 3px 6px rgba(0,0,0,0.5); -moz-box-shadow:3px 3px 6px rgba(0,0,0,0.5); box-shadow:3px 3px 6px rgba(0,0,0,0.5); } #controls{ margin-top:10px; margin-left:15px; } </style> </head> <body onload="init()"> <div id="controls"> <input id='animateBtn' type='button' value='运动'/> </div> <canvas id="canvas" width="750px" height="500px" > 出现文字表示你的浏览器不支持HTML5 </canvas> </body></html><script type="text/javascript"><!--var paused=true;animateBtn.onclick=function(e){ paused=! paused; if(paused){ animateBtn.value="运动"; }else{ animateBtn.value="暂停"; window.requestAnimationFrame(animate); }}//生成从minNum到maxNum的随机数function randomNum(minNum,maxNum){ switch(arguments.length){ case 1: return parseInt(Math.random()*minNum+1,10); break; case 2: return parseInt(Math.random()*(maxNum-minNum+1)+minNum,10); break; default: return 0; break; }}var ctx;// 绘图环境var balls=[];// 球数组function init(){ var canvas=document.getElementById('canvas'); canvas.width=750; canvas.height=500; ctx=canvas.getContext('2d'); for(var i=0;i<500;i++){ var ball={}; ball.x=randomNum(0,canvas.width); ball.y=randomNum(0,canvas.height); ball.vx=randomNum(-10,10); ball.vy=randomNum(-10,10); ball.radius=25; var r=randomNum(0,255); var g=randomNum(0,255); var b=randomNum(0,255); ball.innerColor='rgba('+r+','+g+','+b+',1)'; ball.middleColor='rgba('+r+','+g+','+b+',0.5)'; ball.outerColor='rgba('+r+','+g+','+b+',0.3)'; ball.strokeStyle='rgba('+r+','+g+','+b+')'; balls.push(ball); }};function update(){ for(var i=0;i<balls.length;i++){ var ball=balls[i]; // 与左右墙壁的碰撞检测 if(ball.x+ball.vx+ball.radius>ctx.canvas.width || ball.x+ball.vx-ball.radius<0){ ball.vx=-ball.vx; } // 与上下墙壁的碰撞检测 if(ball.y+ball.vy+ball.radius>ctx.canvas.height || ball.y+ball.vy-ball.radius<0){ ball.vy=-ball.vy; } // 小球之前的碰撞检测 for(var j=0;j<balls.length;j++){ if(i!=j){ var other=balls[j]; var distance=Math.sqrt( Math.pow((ball.x+ball.vx-other.x-other.vx),2)+Math.pow((ball.y+ball.vy-other.y-other.vy),2)); if(distance<ball.radius+other.radius){ // 如果两个碰撞小球的质量相等，联立动量守恒和能量守恒方程时可解得：两个小球碰撞后交换速度。 var x=ball.vx; ball.vx=other.vx; other.vx=x; var y=ball.vy; ball.vy=other.vy; other.vy=y; } } } ball.x+=ball.vx; ball.y+=ball.vy; }}function draw(){ ctx.clearRect(0,0,ctx.canvas.width,ctx.canvas.height); for(var i=0;i<balls.length;i++){ var ball=balls[i]; gradient=ctx.createRadialGradient(ball.x,ball.y,0,ball.x,ball.y,ball.radius); gradient.addColorStop(0.3,ball.innerColor); gradient.addColorStop(0.5,ball.middleColor); gradient.addColorStop(1.0,ball.outerColor); ctx.save(); ctx.beginPath(); ctx.arc(ball.x,ball.y,ball.radius,0,Math.PI*2,false); ctx.fillStyle=gradient; ctx.strokeStyle=ball.strokeStyle; ctx.fill(); ctx.stroke(); ctx.restore(); }}function animate(){ if(!paused){ update(); draw(); setTimeout( function(){ window.requestAnimationFrame(animate); /// 让浏览器自行决定帧速率 }, 0.10 * 1000 );// 延时执行 }}//--></script>
2019年3月4日09点12分
