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<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>Multi Curve 3</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 curves.</aside>
<script>
window.onload = function () {
var canvas = document.getElementById('canvas'),
context = canvas.getContext('2d'),
points = [],
numPoints = 9,
ctrlPoint = {},
ctrlPoint1 = {};
for (var i = 0; i < numPoints; i++) {
points.push({
x: Math.random() * canvas.width,
y: Math.random() * canvas.height
});
}
//find the first midpoint and move to it
ctrlPoint1.x = (points[0].x + points[numPoints-1].x) / 2;
ctrlPoint1.y = (points[0].y + points[numPoints-1].y) / 2;
context.beginPath();
context.moveTo(ctrlPoint1.x, ctrlPoint1.y);
//curve through the rest, stopping at each midpoint
for (i = 0; i < numPoints - 1; i++) {
ctrlPoint.x = (points[i].x + points[i+1].x) / 2;
ctrlPoint.y = (points[i].y + points[i+1].y) / 2;
context.quadraticCurveTo(points[i].x, points[i].y,
ctrlPoint.x, ctrlPoint.y);
}
//curve through the last point, back to the first midpoint
context.quadraticCurveTo(points[i].x, points[i].y,
ctrlPoint1.x, ctrlPoint1.y);
context.stroke();
};
</script>
</body>
</html>