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52 lines
1.7 KiB
HTML
52 lines
1.7 KiB
HTML
<!doctype html>
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<html>
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<head>
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<meta charset="utf-8">
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<title>Multi Curve 3</title>
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<link rel="stylesheet" href="../include/style.css">
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</head>
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<body>
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<header>
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Example from <a href="http://amzn.com/1430236655?tag=html5anim-20"><em>Foundation HTML5 Animation with JavaScript</em></a>
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</header>
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<canvas id="canvas" width="400" height="400"></canvas>
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<aside>Refresh page for random curves.</aside>
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<script>
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window.onload = function () {
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var canvas = document.getElementById('canvas'),
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context = canvas.getContext('2d'),
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points = [],
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numPoints = 9,
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ctrlPoint = {},
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ctrlPoint1 = {};
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for (var i = 0; i < numPoints; i++) {
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points.push({
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x: Math.random() * canvas.width,
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y: Math.random() * canvas.height
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});
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}
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//find the first midpoint and move to it
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ctrlPoint1.x = (points[0].x + points[numPoints-1].x) / 2;
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ctrlPoint1.y = (points[0].y + points[numPoints-1].y) / 2;
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context.beginPath();
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context.moveTo(ctrlPoint1.x, ctrlPoint1.y);
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//curve through the rest, stopping at each midpoint
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for (i = 0; i < numPoints - 1; i++) {
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ctrlPoint.x = (points[i].x + points[i+1].x) / 2;
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ctrlPoint.y = (points[i].y + points[i+1].y) / 2;
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context.quadraticCurveTo(points[i].x, points[i].y,
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ctrlPoint.x, ctrlPoint.y);
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}
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//curve through the last point, back to the first midpoint
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context.quadraticCurveTo(points[i].x, points[i].y,
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ctrlPoint1.x, ctrlPoint1.y);
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context.stroke();
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};
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</script>
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</body>
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</html>
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