Create a deformation cage on a single-face surface.

Input parameters:

1. Sf → Surface to create cage on.
2. Iu → U interval for the subsurface to create the cage on.
3. Iv → V interval for the subsurface to create the cage on.
4. Hg → Height of surface cage.
5. Du → Degree in cage U direction, between 1 and 7.
6. Dv → Degree in cage V direction, between 1 and 7.
7. Dw → Degree in cage W direction, between 1 and 7.

Output parameters:

1. Cg → Deformation cage on surface.