OEGeom3DAngle
template<class T>
double OEGeom3DAngle(const T* p, const T* q)
template<class T, class U, class V>
double OEGeom3DAngle(const T* p, const U* q, const V* r)
Determines the angle in three dimensions. The first form is between
two vectors p and q, and the second form is between three
cartesian coordinate points p, q and r with q
being the vertex. The result is in radians.