blender crash when adding segments on bevel modifier #73450

New Issue

fadil fikrillah · 2020-01-28T08:58:41+01:00

fadil fikrillah commented

2020-01-28 08:58:41 +01:00

System Information
Operating system: Linux-5.4.0-3-amd64-x86_64-with-debian-bullseye-sid 64 Bits
Graphics card: AMD Radeon R6 Graphics (CARRIZO, DRM 3.35.0, 5.4.0-3-amd64, LLVM 9.0.1) X.Org 4.5 (Core Profile) Mesa 19.3.2

Blender Version
Broken: version: 2.81 (sub 16), branch: Unknown, commit date: Unknown Unknown, hash: rBUnknown
Worked: (optional)

Short description of error
blender crash when adding segments on bevel modifier

Exact steps for others to reproduce the error

open the file attached
increment Segments in Bevel modifier
blender should crash

file_updated.blend

**System Information** Operating system: Linux-5.4.0-3-amd64-x86_64-with-debian-bullseye-sid 64 Bits Graphics card: AMD Radeon R6 Graphics (CARRIZO, DRM 3.35.0, 5.4.0-3-amd64, LLVM 9.0.1) X.Org 4.5 (Core Profile) Mesa 19.3.2 **Blender Version** Broken: version: 2.81 (sub 16), branch: Unknown, commit date: Unknown Unknown, hash: `rBUnknown` Worked: (optional) **Short description of error** blender crash when adding segments on bevel modifier **Exact steps for others to reproduce the error** 1. open the file attached 2. increment `Segments` in Bevel modifier 3. blender should crash [file_updated.blend](https://archive.blender.org/developer/F8307116/file_updated.blend)

fadil fikrillah commented

2020-01-28 08:58:41 +01:00

Added subscriber: @fikrillah

Jacques Lucke commented

2020-01-28 09:19:31 +01:00

Changed status from 'Needs Triage' to: 'Confirmed'

Jacques Lucke commented

2020-01-28 09:21:06 +01:00

Added subscribers: @HooglyBoogly, @howardt, @JacquesLucke

Jacques Lucke commented

2020-01-28 09:21:06 +01:00

It crashes in snap_to_pipe_profile due to a failed matrix inversion.

It crashes in `snap_to_pipe_profile` due to a failed matrix inversion.

Pasang Bomjan commented

2020-01-28 09:29:15 +01:00

Added subscriber: @Pasang

Pasang Bomjan commented

2020-01-28 09:29:15 +01:00

Doesn't crash in my system though...

Jacques Lucke commented

2020-01-28 09:31:42 +01:00

It might be that it only crashes deterministically in debug builds because an assert is hit in the code. The error might go unnoticed in release builds when you are unlucky.

Hans Goudey commented

2020-01-28 14:56:53 +01:00

I'll look into this as soon as I get a chance.

Howard Trickey commented

2020-01-29 15:45:13 +01:00

I looked into it some. The problem is that the start and end of some profiles (e.g., for edge 33 between vertices 16 and 93) are the same point. This seems to be because when offset_meet is called during build_boundary, the left and right offsets of beveled edges 33, 35, and 37 are zero. They got set properly in bevel_vert_construct, so not sure where they got reset.

We should fix the snap-to-pipe code to detect when the profile start and end points are the same, and just return the coords of one of those points and avoid the matrix inversion. That will stop the crash. But we should try to figure out why those points are identical in this case, too.

I looked into it some. The problem is that the start and end of some profiles (e.g., for edge 33 between vertices 16 and 93) are the same point. This seems to be because when offset_meet is called during build_boundary, the left and right offsets of beveled edges 33, 35, and 37 are zero. They got set properly in bevel_vert_construct, so not sure where they got reset. We should fix the snap-to-pipe code to detect when the profile start and end points are the same, and just return the coords of one of those points and avoid the matrix inversion. That will stop the crash. But we should try to figure out why those points are identical in this case, too.

Howard Trickey commented

2020-01-30 13:55:26 +01:00

The problem is provoked because the input mesh has some edges that form a zero-degree angle, causing clamp overlap to set the offsets to approximately zero (hence, even with bug fix, this mesh will not bevel noticeably with clamp overlap turned on). Information for bug reporter: an example of the problem are the vertices with indices 44, 17, 73, 10, which form a chain in that order, while it looks like what was intended was that vertex 17 would be in the center of edges going to 10, 73, and 44. You can see vertex indices by selecting Developer Extras in Preferences, then clicking "Indices" in the Display Overlap options, then selecting all the vertices.

My next commit will protect against crashes in this situation and close this bug.

The problem is provoked because the input mesh has some edges that form a zero-degree angle, causing clamp overlap to set the offsets to approximately zero (hence, even with bug fix, this mesh will not bevel noticeably with clamp overlap turned on). Information for bug reporter: an example of the problem are the vertices with indices 44, 17, 73, 10, which form a chain in that order, while it looks like what was intended was that vertex 17 would be in the center of edges going to 10, 73, and 44. You can see vertex indices by selecting Developer Extras in Preferences, then clicking "Indices" in the Display Overlap options, then selecting all the vertices. My next commit will protect against crashes in this situation and close this bug.

blender-admin commented

2020-01-30 13:56:00 +01:00

This issue was referenced by 30963eecfb

This issue was referenced by 30963eecfb3be0dd50624d54f2111e7f1ed49d6b

Howard Trickey commented

2020-01-30 13:58:22 +01:00

Changed status from 'Confirmed' to: 'Resolved'

Howard Trickey closed this issue

2020-01-30 13:58:22 +01:00

Howard Trickey self-assigned this 2020-01-30 13:58:22 +01:00

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blender crash when adding segments on bevel modifier #73450