html5碰撞小球模拟

时间：2024-12-21 10:04:31

这里根据动量守恒和能量守恒定理来计算小球的位置，从而模拟完全弹性碰撞下的小球运行轨迹。

html代码：

 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

 <html xmlns="http://www.w3.org/1999/xhtml">

   <head>

     <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

     <script class="jquery library" src="/js/sandbox/jquery/jquery-1.8.2.min.js" type="text/javascript"></script>

     <title>碰撞小球</title>

   </head>

     <body>

         <canvas id='box' width="300" height="300" style="border:2px; background:black;">

      </canvas>

   </body>

 </html>

js代码：

 //get a random color to render the ball

 function getRandomColor(){

   return (function(m,s,c){

     return (c ? arguments.callee(m,s,c-1) : '#') +

       s[m.floor(m.random() * 16)]

   })(Math,'0123456789abcdef',5)

 }

 //get a random number between min and max

 function getRandomNumber(min, max) {

     return min + Math.ceil(Math.random() * (max - min));

 }

 var balls = [];

 var ballCount = 4;

 var boxLen = 300;

 function createBall() {

     var r = getRandomNumber(10,20);

     var ball = {

         m:r,

         r:r,

         x:getRandomNumber(0,boxLen-2*r),

         y:getRandomNumber(0,boxLen-2*r),

         vx:getRandomNumber(1,3),

         vy:getRandomNumber(1,3),

         color:getRandomColor()

     };

     return ball;

 }

 //test collision

 function checkCollision(b1, b2) {

     var dx = b1.x - b2.x;

     var dy = b1.y - b2.y;

     var dist = Math.ceil(Math.sqrt(dx * dx + dy * dy));

     return dist < b1.r + b2.r;

 }

 //initialize the balls

 for(var i = 0; i < ballCount; i++) {

     var collision = false;

     while(true) {

         var b = createBall();

         for(var j = 0; j < i; j++) {

             collision = checkCollision(b,balls[j]);

             if(collision) break;

         }

         if(!collision) {

             balls[i] = b;

             break;

         }

     }

 }

 function calcV(m1, m2, v1, v2) {

     return ((m1 - m2) * v1 + 2 * m2 * v2) / (m1 + m2);

 }

 function draw() {

     //handle collisions

     for(var i = 0; i < balls.length; i++) {

         for(var j = i + 1; j < balls.length; j++) {

             if(checkCollision(balls[i],balls[j])) {

                 var b1 = balls[i], b2 = balls[j];

                 var v1 = { x : b1.vx, y : b1.vy };

                 var v2 = { x : b2.vx, y : b2.vy };

                 b1.vx = calcV(b1.m, b2.m, v1.x, v2.x);

                 b1.vy = calcV(b1.m, b2.m, v1.y, v2.y);

                 b2.vx = calcV(b2.m, b1.m, v2.x, v1.x);

                 b2.vy = calcV(b2.m, b1.m, v2.y, v1.y);

             }

         }

     }

     //move the balls

     for(var i in balls) {

         var b = balls[i];

         b.x += b.vx;

         b.y += b.vy;

         var closeSide = false;

         var maxPos = boxLen - 2 * b.r;

         if(b.x < 0) {

             b.x = 0;

             closeSide = true;

         } else if(b.x > maxPos) {

             b.x = maxPos;

             closeSide = true;

         }

         if(closeSide)

             b.vx = -1 * b.vx;

         closeSide = false;

         if(b.y < 0) {

             b.y = 0;

             closeSide = true;

         } else if(b.y > maxPos) {

             b.y = maxPos;

             closeSide = true;

         }

         if(closeSide)

             b.vy = -1 * b.vy;

     }

     //draw the balls

     var canvas = document.getElementById('box');

     var ctx = canvas.getContext('2d');

     ctx.fillStyle = "#000";

     ctx.fillRect(0,0,canvas.width, canvas.height);

     for(var i in balls) {

         var b = balls[i];

         ctx.beginPath();

         ctx.arc(b.x+b.r, b.y+b.r, b.r, 0, 2 * Math.PI,true);

         ctx.closePath();

         ctx.fillStyle = b.color;

         ctx.fill();

     }

     setTimeout(draw,10);

 }

 draw();

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