Offset a surface by a given distance.

Input parameters:

1. Sf → Surface to offset.
2. Ds → Signed offset distance. Positive moves along the surface normal.
3. So → When true, the original and offset surfaces are connected to form a closed solid.
4. Cs → Determines how non-tangent junctions between offset faces are resolved.
   • 0 → Per Face
   • 1 → Sharp
   • 2 → Chamfer
   • 3 → Fillet
   • 4 → Loose

Output parameters:

1. Sf → The offset result.