Create a surface whose control-points are coincident with the control-points of a set of curves.

Input parameters:

1. Cr → Loft section curves. The lofting works best when all curves have the same degree and the same number of control-points.
2. Dg → Optional surface degree across the section curves. If omitted, the surface U and V degrees will be the same.

Output parameters:

1. Sf → Surface whose control-points are coincident with the curve points.