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aadennis/ball.html

Created June 23, 2018 21:53
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Bouncing ball - credit to MDN
Raw
ball.html
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>Gamedev Canvas Workshop</title>
<style>
* {
padding: 0;
margin: 0;
}
canvas {
background: hotpink;
display: block;
margin: 0 auto;
}
</style>
</head>
<body>
<canvas id="myCanvas" width="200" height="400"></canvas>
<script>
var canvas = document.getElementById("myCanvas");
var ctx = canvas.getContext("2d");
var ballRadius = 10;
var x = canvas.width / 2;
var y = canvas.height - 30;
var dx = 2;
var dy = -2;
function drawBall() {
ctx.beginPath();
ctx.arc(x, y, ballRadius, 0, Math.PI * 2);
ctx.fillStyle = "white";
ctx.fill();
ctx.closePath();
}
function draw() {
ctx.clearRect(0, 0, canvas.width, canvas.height);
drawBall();
if (x + dx > canvas.width - ballRadius || x + dx < ballRadius) {
dx = -dx;
}
if (y + dy > canvas.height - ballRadius || y + dy < ballRadius) {
dy = -dy;
}
x += dx;
y += dy;
}
setInterval(draw, 10);
</script>
</body>
</html>
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