Chaos::ToBarycentric

Convert the cartesian coordinate into a barycentric corrdinate. Compute barycentric coordinates/weights of Point inside 3D triangle (V0,V1,V2). If point is in triangle plane and inside triangle, coords will be positive and sum to 1. ie if result is a, then vPoint = a.x*V0 + a.y*V1 + a.z*V2.