Blender crashes when beveling many vertices to a sharp point if Lineart is active #94390

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Fen · 2021-12-26T15:54:42+01:00

Fen commented

2021-12-26 15:54:42 +01:00

System Information
Operating system: macOS-12.1-arm64-arm-64bit 64 Bits
Graphics card: Apple M1 Pro Apple 4.1 Metal - 76.3

Blender Version
Broken: version: 3.0.0, branch: master, commit date: 2021-12-02 18:35, hash: f1cca30557
Worked: LTS 2.93.7 hangs for a few seconds, but doesn't seem to crash.

Short description of error
Beveling an n-gon with lots of vertices to a sharp point causes a segfault if a Lineart modifier is using the mesh.

Exact steps for others to reproduce the error

Add a cylinder with 128 sides and a Scene Lineart object
Select the top face
Bevel edges
Drag until the sides meet at a point
Segfault

The attached lineart-bevel-crash.blend file is set up; just bevel and drag and it should crash. I have not tested this on other platforms, however.

lineart-bevel-crash.blend

Full stacktrace: P2682

**System Information** Operating system: macOS-12.1-arm64-arm-64bit 64 Bits Graphics card: Apple `M1` Pro Apple 4.1 Metal - 76.3 **Blender Version** Broken: version: 3.0.0, branch: master, commit date: 2021-12-02 18:35, hash: `f1cca30557` Worked: LTS 2.93.7 hangs for a few seconds, but doesn't seem to crash. **Short description of error** Beveling an n-gon with lots of vertices to a sharp point causes a segfault if a Lineart modifier is using the mesh. **Exact steps for others to reproduce the error** 1. Add a cylinder with 128 sides and a Scene Lineart object 2. Select the top face 3. Bevel edges 4. Drag until the sides meet at a point 5. Segfault The attached lineart-bevel-crash.blend file is set up; just bevel and drag and it should crash. I have not tested this on other platforms, however. [lineart-bevel-crash.blend](https://archive.blender.org/developer/F12776592/lineart-bevel-crash.blend) Full stacktrace: [P2682](https://archive.blender.org/developer/P2682.txt)

Fen commented

2021-12-26 15:54:42 +01:00

Added subscriber: @chemicalcrux

Fen commented

2021-12-26 16:01:57 +01:00

I also get a segfault from the latest commit on master, 28a8d434d5

I also get a segfault from the latest commit on master, 28a8d434d5

YimingWu commented

2021-12-26 17:20:29 +01:00

Added subscriber: @ChengduLittleA

YimingWu self-assigned this 2021-12-26 17:20:29 +01:00

YimingWu commented

2021-12-26 17:20:29 +01:00

I'll take a look

Jesse Yurkovich commented

2021-12-26 23:40:51 +01:00

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

YimingWu commented

2021-12-27 04:14:57 +01:00

It didn't really crash here on my machine but after I bevel it to a sharp point or go further it immediately becomes much more laggy. I need to take a look on what's causing it, maybe there's too much depth in subdividing image bound box (there are more than 256 triangles concentrating inside 1 point so it kinda confuses the algorithm). From the stack trace it could be a memory issue, however on my machine I didn't really see any memory spike, debug info shows only allocated 6 Standalone nodes, total 6291456 Bytes. hummm. This is quite interesting I shall investigate further.

Update: I found the cause of this specific crash, which is cause by a duplicated "edge-boundbox" linking, this added too many edge pointers into a tile that overflows the limit. This bug is probably caused by a merge which it automatically modified some code path that I'm unaware of. ~~HOWEVER After I fix this it still crashes, :/~~

OK it is this problem indeed... And it's fixed now at least for the test file you provided. There's still a internal limit of line art of triangle density, I need to protect that array so it won't get overflowed.

It didn't really crash here on my machine but after I bevel it to a sharp point or go further it immediately becomes much more laggy. I need to take a look on what's causing it, maybe there's too much depth in subdividing image bound box (there are more than 256 triangles concentrating inside 1 point so it kinda confuses the algorithm). From the stack trace it could be a memory issue, however on my machine I didn't really see any memory spike, debug info shows only `allocated 6 Standalone nodes, total 6291456 Bytes.` hummm. This is quite interesting I shall investigate further. ----- Update: I found the cause of this specific crash, which is cause by a duplicated "edge-boundbox" linking, this added too many edge pointers into a tile that overflows the limit. This bug is probably caused by a merge which it automatically modified some code path that I'm unaware of. ~~HOWEVER After I fix this it still crashes, :/~~ OK it is this problem indeed... And it's fixed now at least for the test file you provided. There's still a internal limit of line art of triangle density, I need to protect that array so it won't get overflowed.

YimingWu commented

2021-12-27 07:37:51 +01:00

Changed status from 'Confirmed' to: 'Resolved'

YimingWu closed this issue

2021-12-27 07:37:51 +01:00

YimingWu commented

2021-12-27 07:37:51 +01:00

Added a protect condition to not add too many lines in one tiles in case that you got very dense concentration of geometry in one point like the "bevel to one point" situation.

I may also include a check in the loading stage to discard edges that has zero length and triangles that has zero area.

Added a protect condition to not add too many lines in one tiles in case that you got very dense concentration of geometry in one point like the "bevel to one point" situation. I may also include a check in the loading stage to discard edges that has zero length and triangles that has zero area.

YimingWu commented

2021-12-27 07:45:20 +01:00

The same fix is now included into temp-lineart-contained branch as well to prevent crash. Also it's faster :)

The same fix is now included into `temp-lineart-contained` branch as well to prevent crash. Also it's faster :)

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Blender crashes when beveling many vertices to a sharp point if Lineart is active #94390