Re: Re: [SVG] [Batik] Polygon Area

Wow, Domenico! That is such a neat and concise computation. I didn't know it could be so simple. It will take me a while, I think, to figure out why it would work. Does it work for concave polygons as well as convex ones?



cheers

David

________________________________
From: [email protected] <[email protected]> on behalf of [email protected] [svg-developers] <[email protected]>
Sent: Friday, November 06, 2015 5:26 PM
To: [email protected]
Subject: [svg-developers] Re: [SVG] [Batik] Polygon Area



The code below is JavaScript. Pass X and Y arrays of x and y points (clockwise or counterclockwise), and n number of vertices. If you need it for a path element the SVG JavaScript binding provides dedicated functions like getPointAtLength(), getPathSegAtLength(), etc. to convert the path into polygon points.

    function polygon_area (X, Y, n) {
      var
        area = 0,
        i,
        j = n - 1;

      for (i = 0; i < n; j = i++) {
        area += (X[j] + X[i]) * (Y[j] - Y[i]);
      }

      return Math.abs(area / 2);
    }

Domenico




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Posted by: "Dailey, David P." <[email protected]>
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