Get the control-points, weights and knots of a single NURBS surface.

Input parameters:

1. Sf → Surface to analyse.

Output parameters:

1. Cp → Surface control points.
2. Nu → Number of control points in the surface U direction.
3. Cw → Weights of control points.
4. Ku → Surface knot vector in the U direction.
5. Du → Surface degree in the U direction.
6. Kv → Surface knot vector in the V direction.
7. Du → Surface degree in the V direction.