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<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>Random 8</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>
<aside>Refresh page for random positions.</aside>
<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'),
numDots = 300,
ball0 = new Ball(),
ball1 = new Ball(80);
ball0.x = 100;
ball0.y = canvas.height / 2;
ball1.x = 300;
ball1.y = canvas.height / 2;
function detectCollision (x, y, ball) {
var dx = x - ball.x,
dy = y - ball.y,
dist = Math.sqrt(dx * dx + dy * dy);
return (dist < ball.radius); //true or false
}
while (numDots--) {
//initialize variables
var x = 0,
y = 0;
//if not in ballA AND not in ballB, set new random position
while (!detectCollision(x, y, ball0) && !detectCollision(x, y, ball1)) {
//get random position on canvas
x = Math.random() * canvas.width;
y = Math.random() * canvas.height;
}
context.fillStyle = "#000000";
context.beginPath();
//x, y, radius, start_angle, end_angle, anti-clockwise
context.arc(x, y, 2, 0, (Math.PI * 2), true);
context.closePath();
context.fill();
}
};
</script>
</body>
</html>