hyades.physics.Body.GetClosestPointOnEdge C# (CSharp) 메소드

        public float GetClosestPointOnEdge(Vector2 point, int edgeNum, out Vector2 hitPt, out Vector2 normal, out float edgeD)
        {
            hitPt = new Vector2();
            hitPt.X = 0f;
            hitPt.Y = 0f;

            normal = new Vector2();
            normal.X = 0f;
            normal.Y = 0f;

            edgeD = 0f;
            float dist = 0f;

            Vector2 ptA = pointmass_list[edgeNum].position;
            Vector2 ptB = new Vector2();

            if (edgeNum < (count - 1))
                ptB = pointmass_list[edgeNum + 1].position;
            else
                ptB = pointmass_list[0].position;

            Vector2 toP = new Vector2();
            toP.X = point.X - ptA.X;
            toP.Y = point.Y - ptA.Y;

            Vector2 E = new Vector2();
            E.X = ptB.X - ptA.X;
            E.Y = ptB.Y - ptA.Y;

            // get the length of the edge, and use that to normalize the vector.
            float edgeLength = (float)Math.Sqrt((E.X * E.X) + (E.Y * E.Y));
            if (edgeLength > 0.00001f)
            {
                E.X /= edgeLength;
                E.Y /= edgeLength;
            }

            // normal
            Vector2 n = new Vector2();
            VectorHelper.Perpendicular(ref E, ref n);

            // calculate the distance!
            float x;
            Vector2.Dot(ref toP, ref E, out x);
            if (x <= 0.0f)
            {
                // x is outside the line segment, distance is from pt to ptA.
                //dist = (pt - ptA).Length();
                Vector2.Distance(ref point, ref ptA, out dist);
                hitPt = ptA;
                edgeD = 0f;
                normal = n;
            }
            else if (x >= edgeLength)
            {
                // x is outside of the line segment, distance is from pt to ptB.
                //dist = (pt - ptB).Length();
                Vector2.Distance(ref point, ref ptB, out dist);
                hitPt = ptB;
                edgeD = 1f;
                normal = n;
            }
            else
            {
                // point lies somewhere on the line segment.
                Vector3 toP3 = new Vector3();
                toP3.X = toP.X;
                toP3.Y = toP.Y;

                Vector3 E3 = new Vector3();
                E3.X = E.X;
                E3.Y = E.Y;

                //dist = Math.Abs(Vector3.Cross(toP3, E3).Z);
                Vector3.Cross(ref toP3, ref E3, out E3);
                dist = Math.Abs(E3.Z);
                hitPt.X = ptA.X + (E.X * x);
                hitPt.Y = ptA.Y + (E.Y * x);
                edgeD = x / edgeLength;
                normal = n;
            }

            return dist;
        }