Check point within polygon

Question

int pnpoly(int npol, float *xp, float *yp, float x, float y)
{
   int i, j, c = 0;
   for (i = 0, j = npol-1; i < npol; j = i++) {
     if ((((yp[i] <= y) &&am         


        

Answer 1

Note that if your polygon N and N+1 have the same y value then this test can fail computing vt. For example: determining if a point is inside an axis aligned square.

You need to deal with lines parallel on y