<html>
<head>
<title>小球之间的碰撞(全然弹性碰撞)</title>
<script src="../js/jscex.jscexRequire.min.js" type="text/javascript"></script>
</head> <body>
<canvas id="mc" width="1200px" height="600px">
</canvas>
<script type="text/javascript">
var canvas = document.getElementById('mc');
var cxt = canvas.getContext('2d');
//设置画布背景颜色
cxt.fillStyle = "#030303";
cxt.fillRect(0, 0, canvas.width, canvas.height);
var cyc = 20;
var balls = [];
//定义一个向x轴正前方运动
var ball_1 = {
x:100,
y:550,
r:50,
vx:500,
vy:0
};
//定义一个向x轴反方向运动
var ball_2 = {
x:1000,
y:550,
r:50,
vx:-400,
vy:0
};
balls.push(ball_1);
balls.push(ball_2);
cxt.fillStyle = "#030303";
cxt.fillRect(0,0,canvas.width,canvas.height);
//画出两个小球
function init () {
cxt.fillStyle = "#fff";
for(var i in balls){
cxt.beginPath();
cxt.arc(balls[i].x,balls[i].y,balls[i].r,0,Math.PI*2,true);
cxt.closePath();
cxt.fill();
}
}
init();
var ct
//动态绘出小球相碰撞的情形
var somethingAsync = eval(Jscex.compile("async", function (ct) {
while (true) {
cxt.fillStyle = "rgba(0,0,0,1)";
cxt.fillRect(0,0,canvas.width,canvas.height);
cxt.fillStyle = "#fff";
//小球运动
for(var i in balls){
balls[i].x += balls[i].vx *cyc /1000;
cxt.beginPath();
cxt.arc(balls[i].x,balls[i].y,balls[i].r,0,Math.PI*2,true);
cxt.closePath();
cxt.fill();
//小球触碰左右两个墙壁
if(balls[i].x + balls[i].r >= canvas.width || balls[i].x <= balls[i].r){
balls[i].vx *= -1;
}
}
//推断两个小球是否相互碰撞
if(Math.abs(ball_1.x - ball_2.x) <= 2*50){
var temp = ball_1.vx;
ball_1.vx = ball_2.vx;
ball_2.vx = temp;
}
$await(Jscex.Async.sleep(cyc,ct));
}
}));
//手动控制小球的运动
function Button1_onclick() {
ct.cancel();
}
function Button2_onclick() {
ct = new Jscex.Async.CancellationToken();
somethingAsync(ct).start();
} </script>
<br>
<br />
<br />
<input id="Button2" class="css3btn" type="button" value="run" onclick="return Button2_onclick()" />
<input id="Button1" class="css3btn" type="button" value="stop" onclick="return Button1_onclick()" /> </body>
</html>