The Ufactor normalizes the u parameter to [0,1]. This must be respected, when you define a Value, uDerivation or vDerivation. For example the Cone has a UFactor 2*PI. in the Value method we have double x = System.Math.Cos(u * UFactor); double y = System.Math.Sin(u * UFactor); double z = v * VFactor;

The Vfactor normalizes the v parameter to [0,1]. This must be respected, when you define a Value, uDerivation or vDerivation. For example the Cone has a UFactor 2*PI. in the Value method we have double x = System.Math.Cos(u * UFactor); double y = System.Math.Sin(u * UFactor); double z = v * VFactor;