Creating Windows on a non-planar surface

In the attached file I have a profile of a window I am trying to create in a surface. The “frame” is the projection of a planar window shape on the surface.

My thought was to create the window opening by using the shape to create a surface, extrude the surface, then subtract the extrusion (offsetsrf).

Problem Windows.3dm (3.0 MB)

The problem that when i try to use edgesrf or notworksrf then offsetsrf, I get a weird shape (note surfaces at the side)

It does work if I use Patch but patch is very slow.

I am not wondering if I am approaching this in the wrong way and, if so, how to go about doing this.

Create a “rectangular” window with sharp corners on the surface, then trim the corners.

Hard to say without the surface, but Split on the surface with the window curves seems like it might be what you want.


The curve is so close to planar that I have to ask… why not just use SetPt to flatten it and then PlanarSrf?

There is a large number of these windows that vary in shape. I must not have picked one that is far from planar—but many are.