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Wrong mesh subdivision with inconsistent normals
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System Information
Operating system: Windows 10 Enterprise Version 1803
Graphics card: 2 x GTX1080 ti

Blender Version
blender2.8, 2018-12-05

From latest builds subsurf modifier make a wrong subdivision of geometry as displayed in the attached files.
Before 18/20 November the behaviour of subsurf modifier was ok.
I am sure because I did an animation on that date and the subdivided vase was ok.

Best regards,




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Brecht Van Lommel (brecht) triaged this task as Needs Information from User priority.

Thanks for the report, but we need a .blend file to reproduce the problems.

Umberto Celentano (umbcel) updated the task description. (Show Details)EditedDec 5 2018, 11:41 AM

Hi Bretch,
sorry, I forgot to add it.
Now I added it to original post.

Have a great day,


Brecht Van Lommel (brecht) raised the priority of this task from Needs Information from User to Normal.

Hi guys,
as reported by a my friend the recalc of the outside normals solve the problem.
So at this point I am not sure if it's a bug or something else.

Normally that should not affect the subdivision result, so still seems like a bug.

OpenSubdiv expects topology to be ordered in an uniform manner. This is exactly what's happening when you invoke "Make normals consistent".

We would need to do some sort of ordering before sending topology to OpenSubdiv, but first we need to have topology cache implemented, to reduce penalty which will be brought by the orientation process.

Hi Sergey,
thank you so much for your clear answer.