Create a flow deformation which maps onto a surface UVW space. If an input shape is provided, it will be deformed accordingly.

Input parameters:

1. Sh → Optional shape to deform.
2. Sr → Source space in the form of a rectilinear box.
3. Tr → Target surface for flow deformation.
4. Du → Optional U domain for target space. If omitted, the entire domain will be used.
5. Dv → Optional V domain for target space. If omitted, the entire domain will be used.
6. Fw → Scaling factor in the surface normal direction.

Output parameters:

1. Sh → Shape with applied deformation.
2. Df → Flow deformation.