Narek Saribekyan wrote:
> Here is the most known method to test if point is inside polygon.
>
> p polygon
> n number of vertices in polygon
> q point
>
> RightHorizontalRayIntersection(q,u,v) tests if horizontal ray starting
> from point q (in right direction) intersects a segment (u,v).
>
> bool IsPointInsidePolygon( P *p,int n,P q ) {
> int i,j,c=0;
> for (i=0,j=n-1; i<n; j=i++) // Considering all segments (p[i],p[j])
> if (RightHorizontalRayIntersection( q,p[i],p[j] )) c++;
> return c%2;
> }
>
> There are some special cases.
> 1. Ray r intersects a segment in one of it's vertices.
> 2. Ray r is collinear to one of p's segments.
> 3. Point q is lying on one of p's segments.
>
See
http://www.ecse.rpi.edu/Homepages/wrf/Research/Short_Notes/pnpoly.html
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