///Returns whether a line segment intersects a polygon (given a list of vertices)
        public static bool LineSegIntersectsPoly(LineSeg lns, List <Vector2> verts)
        {
            //Check to see if either end of the segment is in the polygon
            if (PointInPoly(lns.CenterA, verts) || PointInPoly(lns.CenterB, verts))
            {
                return(true);
            }

            int     j        = verts.Count - 1;
            LineSeg lnsCheck = new LineSeg();

            //checks every line segment in the polygon until an intersection is found
            for (int i = 0; i < verts.Count; i++)
            {
                lnsCheck.SetA(verts[i]);
                lnsCheck.SetB(verts[j]);
                if (LineSegIntersectsLineSeg(lns, lnsCheck))
                {
                    return(true);
                }

                j = i;
            }

            return(false);
        }
        /* Poly methods */

        #region

        ///Returns whether a polygon intersects another polygon (given a list of vertices)
        public static bool PolyIntersectsPoly(List <Vector2> verts1, List <Vector2> verts2)
        {
            //check to see if any vertices exist inside either polygon (more efficient and catches most cases)
            for (int i = 0; i < verts1.Count; i++)
            {
                Vector2 vert = verts1[i];

                if (PointInPoly(vert, verts2))
                {
                    return(true);
                }
            }

            for (int i = 0; i < verts2.Count; i++)
            {
                Vector2 vert = verts2[i];

                if (PointInPoly(vert, new List <Vector2>(verts1)))
                {
                    return(true);
                }
            }

            //check to see if any of the edges of a polygon intersect with the edges of the other
            //this code ensures concave shapes work too but it's potentially slow
            LineSeg lnsCheck = new LineSeg();
            int     j        = verts1.Count - 1;

            for (int i = 0; i < verts1.Count; i++)
            {
                lnsCheck.SetA(verts1[i]);
                lnsCheck.SetB(verts1[j]);
                if (LineSegIntersectsPoly(lnsCheck, verts2))
                {
                    return(true);
                }

                j = i;
            }

            return(false);
        }
        ///Returns whether a point lies on the perimeter of a polygon given its vertices
        public static bool PointOnPolyPerimeter(Vector2 p, List <Vector2> verts)
        {
            LineSeg lineCheck = new LineSeg();
            int     j         = verts.Count - 1;

            //checks every line segment of the polygon to see if the point lies on any segment
            for (int i = 0; i < verts.Count; i++)
            {
                lineCheck.SetA(verts[i]);
                lineCheck.SetB(verts[j]);
                if (PointOnLineSeg(p, lineCheck))
                {
                    return(true);
                }

                j = i;
            }

            return(false);
        }
        ///Returns whether a circle intersects a polygon (given a list of vertices)
        public static bool CircleIntersectsPoly(Circle c, List <Vector2> verts)
        {
            //check to see if the center of the circle is in the poly
            if (PointInPoly(c.WorldCenter, verts))
            {
                return(true);
            }

            //check to see if any points are in the circle
            for (int i = 0; i < verts.Count; i++)
            {
                Vector2 vert = verts[i];

                if (PointInCircle(vert, c))
                {
                    return(true);
                }
            }

            LineSeg lnsCheck = new LineSeg();
            int     j        = verts.Count - 1;

            //check each line segment of the polygon until an intersection is found
            for (int i = 0; i < verts.Count; i++)
            {
                lnsCheck.SetA(verts[i]);
                lnsCheck.SetB(verts[j]);
                if (LineSegIntersectsCircle(lnsCheck, c))
                {
                    return(true);
                }

                j = i;
            }

            return(false);
        }