Surfaces warp when joined


when I join the sufaces pictured below into a closed polysurface, the walls will appear all warped. What is happening here? How can I fix this?

Warped Extrusion.3dm (6.7 MB)

Unjoined surfaces above, joined to a closed polysurface below.

Hello - please run the command DivideAlongCreases > SplitAtTangents=Yes, on these objects.



Thank you!

Hello - the underlying problem is that single surfaces that are not curvature continuous internally, like tangent arcs and straights, cause problems with the default settings for the display mesh - you can also often ‘fix’ the problem by changing the mesh settings in DocumentProperties, but unless there is a reason to keep the surfaces as single surfaces, I’d generally want to split them up.


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Can I use this command in Grasshopper, perhaps via ghPython? I can’t seem to find the appropriate method here.

Or can I avoid the issue alltogether? So far, I’m creating a boundary surface from a planar curve and extrude that, to the effect shown above.

Yeah, nothing jumps out at me in RhinoCommon - can you send me the python you are using, and a couple of sample input curves?


Ah, sorry for not being clearer, I am not using ghPython for this. That’s just my go-to for when I need something that’s not available as a component.

This is how I’m currently creating the extrusions. I’d hoped I could simply chain the DivideAlongCreases operation to the end, rather than bake and run the command manually.

Warped (388.1 KB)

Thank you for taking the time to look into this!

@messismore - put a Simplify Curve component between curve and boundary…

Any better?


Even with the tolerance cranked up I get some of these errors, unfortunately:

Yes, one or two here as well.

@messismore - see how this works - not extensively tested but in your example it seems to work.

Warped (393.7 KB)
It splits up the extrusions via a Python script and then caps the result.


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That appears to work. Thank you!