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Blender 2.71 (rc2) crashes when a UV sphere is added
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System Information
Mac OS X 10.10 (beta) / AMD Radeon HD 6750M 512 MB

Blender Version
Broken: 2.71 (release candidate 2)
Worked: -

Short description of error
Blender 2.71 (rc2) crashes when a UV Sphere is added to a existent project in Edit Mode.

Exact steps for others to reproduce the error
Using the attached file, select the figure (stickman), go to Edit Mode and add a UV Sphere. After executing these steps, Blender stops responding and it's necessary to force quit and reopen.

It seems that's something to do with the modifiers (in the attached file, I'm using Mirror, Skin and Sub-surf). One or more of them are causing the crash when the UV Sphere is added. If I create a new project with no modifiers, I'm able to add UV Sphere.


To Do

Event Timeline

Hiram (hiram) added a project: BF Blender.
Hiram (hiram) set Type to Bug.
Hiram (hiram) added a subscriber: Hiram (hiram).
Hiram (hiram) created this task.
Hiram (hiram) raised the priority of this task from to Needs Triage by Developer.
Bastien Montagne (mont29) triaged this task as Needs Information from User priority.

Cannot confirm that with default cube, and you did not attach your file…

I tested this here and can confirm it with RC2 as well as official 2.70. The freeze happens only with the skin modifier. Mirror and subsurf work without problems. There are a multiple ways to reproduce the bug.

  • Have an object with skin modifier and create a UV sphere in edit mode.
  • Have a UV sphere and give it a skin modifier.

There is one thing I also noticed with the skin modifier. If it's applied to a default plane, you get a result 1. Then in edit mode, create a new plane and you get a result 2, the new plane is weird, it doesn't have the modifier's effect. Select the new plane and do "mark root" from the skin modifier panel and you get a proper result as shown in 3.

In addition, It's not only the UV sphere, I get a slow-down with an ico sphere, cylinder, monkey head as well. It's slow to create the new mesh in edit mode and also slow when editing (even after "mark as root").

System Information
Windows 7, 64bit, mobility radeon 5650.

Blender Version
Blender 2.71 RC2 win64
Blender 2.70 official release, win64

Bastien Montagne (mont29) raised the priority of this task from Needs Information from User to Normal.Jun 23 2014, 3:45 PM

Can’t get it crashing here, but yes, with a Skin modifier it’s damn slow. Not really sure there is a bug here, though…

Assigning to Campbell, that’s his area of code! :)

I noticed that the more complex the base mesh with a skin modifier, the longer it takes. My guess is when the mesh is complex enough, Blender takes so long and is unresposive, it looks like it froze. It didn't actually ever crash here.

This is indeed performance issue, committed improvement rB92733179aee8d7997c843149dfb640a508ade647

However this modifier just performs terribly when adding solid geometry.

@Bastien Montagne (mont29), This modifier uses bmesh-operators really inefficiently, I think it needs to be re-written (or have a large refactor) to resolve this problem.

Thanks for checking on this, guys!

I didn't express myself correctly: indeed it seems to freeze, it doesn't crash. As the operating system was indicating the process as "not responding", I assumed the operation would never be completed.

I think a workaround would be to add a "progress bar" somewhere while this feature waits to be optimized/rewritten. I was able to workaround the issue by applying the skin modifier before adding the UV sphere. In this case I was making a stickman where the edges needed the skin modifier and the UV sphere should be the head. Anyway, I don't know if it makes sense applying the Skin Modifier to a UV sphere. It was accidental.

Let me know if I can share anything else. I'd be pleased to help.