Permalink
Switch branches/tags
Nothing to show
Find file Copy path
Fetching contributors…
Cannot retrieve contributors at this time
122 lines (113 sloc) 3.98 KB
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>Billiard 4</title>
<link rel="stylesheet" href="../include/style.css">
</head>
<body>
<header>
Example from <a href="http://amzn.com/1430236655?tag=html5anim-20"><em>Foundation HTML5 Animation with JavaScript</em></a>
</header>
<canvas id="canvas" width="400" height="400"></canvas>
<script src="../include/utils.js"></script>
<script src="./classes/ball.js"></script>
<script>
window.onload = function () {
var canvas = document.getElementById('canvas'),
context = canvas.getContext('2d'),
ball0 = new Ball(80),
ball1 = new Ball(40),
bounce = -1.0;
ball0.mass = 2;
ball0.x = canvas.width - 200;
ball0.y = canvas.height - 200;
ball0.vx = Math.random() * 10 - 5;
ball0.vy = Math.random() * 10 - 5;
ball1.mass = 1;
ball1.x = 100;
ball1.y = 100;
ball1.vx = Math.random() * 10 - 5;
ball1.vy = Math.random() * 10 - 5;
function rotate (x, y, sin, cos, reverse) {
return {
x: (reverse) ? (x * cos + y * sin) : (x * cos - y * sin),
y: (reverse) ? (y * cos - x * sin) : (y * cos + x * sin)
};
}
function checkCollision (ball0, ball1) {
var dx = ball1.x - ball0.x,
dy = ball1.y - ball0.y,
dist = Math.sqrt(dx * dx + dy * dy);
//collision handling code here
if (dist < ball0.radius + ball1.radius) {
//calculate angle, sine, and cosine
var angle = Math.atan2(dy, dx),
sin = Math.sin(angle),
cos = Math.cos(angle),
//rotate ball0's position
pos0 = {x: 0, y: 0}, //point
//rotate ball1's position
pos1 = rotate(dx, dy, sin, cos, true),
//rotate ball0's velocity
vel0 = rotate(ball0.vx, ball0.vy, sin, cos, true),
//rotate ball1's velocity
vel1 = rotate(ball1.vx, ball1.vy, sin, cos, true),
//collision reaction
vxTotal = vel0.x - vel1.x;
vel0.x = ((ball0.mass - ball1.mass) * vel0.x + 2 * ball1.mass * vel1.x) /
(ball0.mass + ball1.mass);
vel1.x = vxTotal + vel0.x;
//update position
pos0.x += vel0.x;
pos1.x += vel1.x;
//rotate positions back
var pos0F = rotate(pos0.x, pos0.y, sin, cos, false),
pos1F = rotate(pos1.x, pos1.y, sin, cos, false);
//adjust positions to actual screen positions
ball1.x = ball0.x + pos1F.x;
ball1.y = ball0.y + pos1F.y;
ball0.x = ball0.x + pos0F.x;
ball0.y = ball0.y + pos0F.y;
//rotate velocities back
var vel0F = rotate(vel0.x, vel0.y, sin, cos, false),
vel1F = rotate(vel1.x, vel1.y, sin, cos, false);
ball0.vx = vel0F.x;
ball0.vy = vel0F.y;
ball1.vx = vel1F.x;
ball1.vy = vel1F.y;
}
}
function checkWalls (ball) {
if (ball.x + ball.radius > canvas.width) {
ball.x = canvas.width - ball.radius;
ball.vx *= bounce;
} else if (ball.x - ball.radius < 0) {
ball.x = ball.radius;
ball.vx *= bounce;
}
if (ball.y + ball.radius > canvas.height) {
ball.y = canvas.height - ball.radius;
ball.vy *= bounce;
} else if (ball.y - ball.radius < 0) {
ball.y = ball.radius;
ball.vy *= bounce;
}
}
(function drawFrame () {
window.requestAnimationFrame(drawFrame, canvas);
context.clearRect(0, 0, canvas.width, canvas.height);
ball0.x += ball0.vx;
ball0.y += ball0.vy;
ball1.x += ball1.vx;
ball1.y += ball1.vy;
checkCollision(ball0, ball1);
checkWalls(ball0);
checkWalls(ball1);
ball0.draw(context);
ball1.draw(context);
}());
};
</script>
</body>
</html>