HTML Canvas Quadratic Curve Random Curve 3

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HTML Canvas Quadratic Curve Random Curve 3

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<!doctype html>
<html>
  <head>
    <meta charset="utf-8">
    <title>Multi Curve 3</title>
  </head>/* w ww.j a va  2 s  .  c  o  m*/
  <body>
    <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 = 19,
          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>



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