Surface Split - Easy case, yet failed

I’m curious about this case of GH Surface Split. It looks for me like a non-complicated scenario yet it fails to cut two surfaces. I tried with different document tolerances and it didn’t make any change.

Is there something I’m missing? Should it work (is it a bug?)? Should I always take the extra steps of preparation? - like projecting curves on the surfaces rather than a shared plane?

Rhino 7.11.21278
surface split (31.0 KB)

  1. Surfaces are planar and to be sure, both surfaces and cutting curves are projected on the same XY Plane.

A) The cutting curve is closed. 2 out of 3 surfaces are cut only in one place (instead of 2) - Fail

B) Cut is being made by 2 open sub-curves from the original closed cutting curve - Success

  1. Cutting closed curve instead of being projected on the same XY plane, is projected on surfaces. In this scenario, everything is being cut as it should.

(Weird because both GH components have the same name)

You can manipulate the shape of the cutting curve and you will see that sometimes split works, and sometimes it doesn’t.

Use scripting, with false it cut in any view , with true you must choose the normal vector

surface split (37.1 KB)

1 Like

Thank you, your script seems to work well. I will keep it among my tools.

Do you know why native Surface Split is working this way? Can anyone confirm if it’s a bug? Can it be fixed? Surface Split is a pretty essential component IMO.

Maybe it is a bug

Hi Jakub -

This should probably work, yes. I’ve put it on the list as RH-65898.
First calculating the intersections and using these curves will correctly split the surfaces: