Convert path to polygon


Question

I'm trying to figure if a point is in a SVG path using Python.
The algorithm that I'll use is the raycasting algorithm.

But for this algorithm i need to have the polygon sides, but all I have is the the pathdata for the svg path:

<path
   d="m 362.26878,978.51017 c 20.15947,-20.15479 23.0826,-25.35876
        20.51836,-36.58367 -5.62899,-24.66928 -8.85902,-84.94939
        -4.6845,-87.51832 2.29504,-1.43086 25.27371,2.13445 51.0669,7.87678
        39.48315,8.80707 50.0611,13.213 66.91495,27.88988 11.39966,9.91685
        25.01402,17.41113 31.62525,17.41113 12.91547,0 24.69288,-11.04544
        19.95645,-18.71919 -1.68587,-2.73893 4.50508,-38.63785 13.76077,-79.78795
        12.41964,-55.21781 16.82552,-85.81829 16.82552,-116.84379 0,-23.12039 … z" />

that corresponds to this image:

SVG Path example

So, is there a way to get the sides of a path?

1
6
11/13/2011 4:10:51 AM

Accepted Answer

You can convert a path into a polygon as shown in my example here:
http://phrogz.net/svg/convert_path_to_polygon.xhtml

The simpler algorithm from that page (in JavaScript) is:

function polygonSampledFromPath(path,samples){
  var doc = path.ownerDocument;
  var poly = doc.createElementNS('http://www.w3.org/2000/svg','polygon');

  var points = [];
  var len  = path.getTotalLength();
  var step = step=len/samples;
  for (var i=0;i<=len;i+=step){
    var p = path.getPointAtLength(i);
    points.push( p.x+','+p.y );
  }
  poly.setAttribute('points',points.join(' '));
  return poly;
}

Instead of sampling based on a certain number of points, you may wish to simply sample at a particular distance.

This assumes that your Python binding has access to the full SVGPathElement DOM Interface.

5
11/11/2011 1:20:35 PM

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