How can you find the centroid of a concave irregular polygon in JavaScript?

Question

How can you find the centroid of a concave irregular polygon given its vertices in JavaScript?

I want to pass a set of x,y points to a JavaScript function and be giv

Answer 1

For the centroid of the 2D surface (which is likely to be what you need), The best is to start with a little bit of maths.

I adapted it here to your own notation :

function get_polygon_centroid(pts) {
   var first = pts[0], last = pts[pts.length-1];
   if (first.x != last.x || first.y != last.y) pts.push(first);
   var twicearea=0,
   x=0, y=0,
   nPts = pts.length,
   p1, p2, f;
   for ( var i=0, j=nPts-1 ; i