fCraft.ShapesLib.CalculateConcaveRadius C# (CSharp) Method

        private double CalculateConcaveRadius( int num_points, int skip )
        {
            // For really small numbers of points.
            if ( num_points < 5 )
                return 0.33f;

            // Calculate angles to key points.
            double dtheta = 2 * Math.PI / num_points;
            double theta00 = -Math.PI / 2;
            double theta01 = theta00 + dtheta * skip;
            double theta10 = theta00 + dtheta;
            double theta11 = theta10 - dtheta * skip;

            // Find the key points.
            PointF pt00 = new PointF(
                ( float )Math.Cos( theta00 ),
                ( float )Math.Sin( theta00 ) );
            PointF pt01 = new PointF(
                ( float )Math.Cos( theta01 ),
                ( float )Math.Sin( theta01 ) );
            PointF pt10 = new PointF(
                ( float )Math.Cos( theta10 ),
                ( float )Math.Sin( theta10 ) );
            PointF pt11 = new PointF(
                ( float )Math.Cos( theta11 ),
                ( float )Math.Sin( theta11 ) );

            // See where the segments connecting the points intersect.
            bool lines_intersect, segments_intersect;
            PointF intersection, close_p1, close_p2;
            FindIntersection( pt00, pt01, pt10, pt11,
                out lines_intersect, out segments_intersect,
                out intersection, out close_p1, out close_p2 );

            // Calculate the distance between the
            // point of intersection and the center.
            return Math.Sqrt(
                intersection.X * intersection.X +
                  intersection.Y * intersection.Y );
        }