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Sub-surf is very slow on high edge-count vertex poles
Open, Confirmed, MediumPublic


System Information
Operating system: Windows 10
Graphics card: GeForce GTX 1050 TI

Blender Version
Broken: blender-2.80.0-git.7d4d9e9dbd3-windows64
Worked: blender-2.79b

Short description of error

NOTE: This is similar to bug (T58191), but different, as I'll explain after the steps.

When a single subdivision surface modifier with 1 subdivision is placed on an object with a high edge-count vertex, it all but stops working.

Exact steps for others to reproduce the error

  1. Open default startup and delete everything.
  2. Add a cylinder with 128 vertices and a triangle fan cap (even worse with n-gon).
  3. Add a subdivision surface modifier with 1 subdivision.
  4. Go into edit mode.
  5. Listen to your fan scream.

How it's different from the aforementioned bug:

The face count for this cylinder is only 384, as compared to 500 faces of the monkey mesh, but adding the same simple modifier to the monkey has no issue. The primary difference I can see is that the cylinder has vertices with a high edge count.

If you follow the same steps in Blender 2.79b, the problem does not occur, which leads me to believe there are some wrinkles in the Catmull-Clark implementation for 2.8 that need to be ironed out.

Thank you.



Event Timeline

Sebastian Parborg (zeddb) renamed this task from Simple sub-surf breaks on high edge-count vertex to Sub-surf is very slow on high edge-count vertex poles.Dec 14 2018, 3:33 PM
Sebastian Parborg (zeddb) triaged this task as Confirmed, Medium priority.

It seems like opensubdiv is very slow when having meshes with extreme cases of vertex poles.

Don't know if there is much to do about this. What do you think @Sergey Sharybin (sergey) ?

same happens with no ngons
Just insert the subdiv. on this model ( low poly )