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Maniphest T50064

When Bevel modifier is applied to specific mesh Blender crashes
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Description

System Information
Windows 7 professional 64-bit
Processor:
Intel Core 2 duo CPU p8400@2.26GHz
RAM: 2GB
Graphics: Mobile Intel 4 Series Express Chipset Family (apologies if not correct, will correct if need be)

Blender Version
Broken: 2.77 abf6f08

A previously applied bevel modifier was added to a .blend, and made invisible. After editing and joining 2 meshes, array modifier was tested, and worked wonderfully. Bevel modifier was made visible and cause blender to crash immediately.

Exact steps for others to reproduce the error

Gears; (time 5_53).blend443 KBDownload

  1. Open .blend
  2. Make bevel modifier visible
  3. Crash

or

  1. Remove bevel modifier
  2. reapply bevel
  3. Blender crashes

Event Timeline

Chaz Fried (PhantomModeler) created this task.Nov 17 2016, 7:56 PM
Sergey Sharybin (sergey) assigned this task to Howard Trickey (howardt).Nov 18 2016, 10:43 AM
Sergey Sharybin (sergey) lowered the priority of this task from 90 to 50.
Sergey Sharybin (sergey) added subscribers: Howard Trickey (howardt), Sergey Sharybin (sergey).

Can reproduce crash with latest master.

@Howard Trickey (howardt), mind having a look here? :) Thanks!

Howard Trickey (howardt) added a comment.Nov 18 2016, 5:26 PM

Hope to get to this soon.

Howard Trickey (howardt) added a comment.Dec 8 2016, 1:55 PM

Looking at this now. It seems that the mesh in the test file violates the assumed invariants about BMeshes. If you start blender with --debug, and then toggle into Edit mode, the validation code reports that a particular face has a duplicate vertex and a duplicate edge.

I will try to make bevel not crash when this happens, but curious if you (PhantomModeler) remember how you made this mesh, as we should try to figure out which editing tool created this mess. (By the way, even without the integrity problem, there also some vertices that are extremely close together that you probably intended to merge. I'm guessing that perhaps Knife was used and it didn't snap to a vertex, but instead to an edge near the intended vertex.)

Howard Trickey (howardt) changed the task status from Unknown Status to Resolved.Dec 14 2016, 2:32 PM

We write our tools under the assumption that the meshes are 'valid'. (If you run the python command mesh.validate(True) it can tell you whether the mesh is valid or not. Rather than try to put all sorts of protective code in all the tools, our policy is to instead make sure no tools produce invalid meshes. At any rate, even if Blender didn't crash, most tools could produce crap results on invalid meshes. Clearly some tool has produced your corrupt mesh -- in the example .blend file that you uploaded -- but without help understanding how that mesh was produced, I'm afraid there's nothing more than can be done here.
Closing this bug, but feel free to open a new bug or reopen this if you can reproduce the mesh corruption (that is, can provide an uncorrupted model and instructions for a next step that causes corruption).
Thanks anyway for the report.

Matthias Thurau (Zweistein) added a subscriber: Matthias Thurau (Zweistein).May 24 2017, 11:04 PM

Cant you simply add that test "mesh.validate(True)" before you add the modifier? Blender keeps crashing and my work is not saved. This is really annoying as that crash happens all the time. Im using boolean to create my meshes.

Campbell Barton (campbellbarton) added a subscriber: Campbell Barton (campbellbarton).May 25 2017, 12:50 PM

Validate is too slow, it needs to be done for any operation that might generate bad data.

It seems there is a bug in the gears add-on. Will check on making it validate all its output.

Campbell Barton (campbellbarton) changed the task status from Resolved to Unknown Status.May 25 2017, 12:50 PM
Howard Trickey (howardt) added a comment.May 25 2017, 12:56 PM

Hi Matthias,

We'd rather have the buggy tools that create invalid meshes call validate() afterwards (this fixes most of the problems), rather than have every tool in blender call validate() before running. In case of original report here, Gears is known to be buggy. Carve boolean is also known to be buggy -- is that the one you are using?

Campbell Barton (campbellbarton) added a comment.May 25 2017, 2:30 PM

Note if you can re-create the cause of a corrupt mesh, this is worth reporting as a separate bug.