Segfault (missing MTFace cdlayer from SubSurf DM). #45749

New Issue

Zauber Paracelsus · 2015-08-10T18:38:32+02:00

Zauber Paracelsus commented

2015-08-10 18:38:32 +02:00

System Information
System 1: 64bit Manjaro Linux 3.19.8.4
System 2: 64bit Windows 8.1

Blender Version
Broken: 2.76-devel 65c3207
Worked: 2.75-release d6b042b

Short description of error
This issue has pretty much stopped me in my tracks. If I use any kind of image texture in a hair or fur shader, then Blender will crash while trying to syncronize the object which has the fur or hair system.

The issue occurs on both Windows and Linux, with CPU and GPU rendering, and with both the Supported and Experimental feature sets. I have also tried doing a complete factory reset (delete config/blender, open file with "Load UI" disabled), and the issue still occurs.

Only Image Textures (both packed and not packed) appear to reproduce the issue. Other types of textures (such as noise) appear to work correctly.

Exact steps for others to reproduce the error
Attempt to render the following file: Test.blend

Crash Log: Test.crash.txt

**System Information** System 1: 64bit Manjaro Linux 3.19.8.4 System 2: 64bit Windows 8.1 **Blender Version** Broken: 2.76-devel 65c3207 Worked: 2.75-release d6b042b **Short description of error** This issue has pretty much stopped me in my tracks. If I use any kind of image texture in a hair or fur shader, then Blender will crash while trying to syncronize the object which has the fur or hair system. The issue occurs on both Windows and Linux, with CPU and GPU rendering, and with both the Supported and Experimental feature sets. I have also tried doing a complete factory reset (delete config/blender, open file with "Load UI" disabled), and the issue still occurs. Only Image Textures (both packed and not packed) appear to reproduce the issue. Other types of textures (such as noise) appear to work correctly. **Exact steps for others to reproduce the error** Attempt to render the following file: [Test.blend](https://archive.blender.org/developer/F222898/Test.blend) Crash Log: [Test.crash.txt](https://archive.blender.org/developer/F222901/Test.crash.txt)

Zauber Paracelsus commented

2015-08-10 18:38:32 +02:00

Changed status to: 'Open'

Zauber Paracelsus commented

2015-08-10 18:38:32 +02:00

Added subscriber: @ZauberParacelsus

Zauber Paracelsus commented

2015-08-10 18:41:05 +02:00

After posting this, I ran a quick test. It appears that when the viewport is set to Preview rendering mode, the crash does not occur. It only seems to happen when I execute a final render.

Zauber Paracelsus commented

2015-08-10 21:14:55 +02:00

This comment was removed by @ZauberParacelsus

*This comment was removed by @ZauberParacelsus*

Zauber Paracelsus commented

2015-08-10 21:38:59 +02:00

Further info: the fur in the example file I gave was not actually using the material with the texture. Setting the correct material to the hair system still reproduces the issue, and further testing reveals that simply having a textured material present in the object's materials will reproduce the issue, whether or not that material is used.

perfection cat commented

2015-08-11 05:25:04 +02:00

Added subscriber: @sindra1961

perfection cat commented

2015-08-11 05:25:04 +02:00

I think that a cause is not the matter that you pointed out.
blender crashes for EXCEPTION_ACCESS_VIOLATION when I use the file which you attached.
However, it does not crash when I change some items.
A change point.
I set a order of Subdivision Surface Modifier last.
Probably I think that it is caused by Subdivision Surface Modifier.
{F223137}A_Test.blend
version 2.75 (sub 4), branch b'master', commit date b'2015-08-09' b'17:17', hash b'65c3207', b'Release'

I think that a cause is not the matter that you pointed out. blender crashes for EXCEPTION_ACCESS_VIOLATION when I use the file which you attached. However, it does not crash when I change some items. A change point. I set a order of Subdivision Surface Modifier last. Probably I think that it is caused by Subdivision Surface Modifier. {[F223137](https://archive.blender.org/developer/F223137/A_Test.blend.png)}[A_Test.blend](https://archive.blender.org/developer/F223139/A_Test.blend) version 2.75 (sub 4), branch b'master', commit date b'2015-08-09' b'17:17', hash b'65c3207', b'Release'

Zauber Paracelsus commented

2015-08-11 16:48:10 +02:00

Well, that's extra strange, then.

And yeah, EXCEPTION_ACCESS_VIOLATION is the error that gets reported on Windows systems. On Linux systems, the error reported is segmentation fault.

Well, that's extra strange, then. And yeah, EXCEPTION_ACCESS_VIOLATION is the error that gets reported on Windows systems. On Linux systems, the error reported is segmentation fault.

Zauber Paracelsus commented

2015-08-11 17:07:50 +02:00

For some reason, I had the subsurf modifier disabled for preview render. After turning it on, the crash now begins to occur when the viewport is set to Rendered mode.

In any case, I did some further testing and found yet another condition for triggering this crash! This condition once again deals with the textured material, and the condition is that the texture is using UV inputs as the texture coordinates. If you instead plug in things like generated or normal Texture Coordinates, the crash does not occur.

This leads me to believe that UV mapping is the underlying problem since the subdivision modifier can change an object's UV mapping. However, toggling the the "Subdivide UVs" option under the subsurf modifier doesn't stop the issue from happening. So, not sure if that's the cause either.

For some reason, I had the subsurf modifier disabled for preview render. After turning it on, the crash now begins to occur when the viewport is set to Rendered mode. In any case, I did some further testing and found yet another condition for triggering this crash! This condition once again deals with the textured material, and the condition is that the texture is using UV inputs as the texture coordinates. If you instead plug in things like generated or normal Texture Coordinates, the crash does not occur. This leads me to believe that UV mapping is the underlying problem since the subdivision modifier can change an object's UV mapping. However, toggling the the "Subdivide UVs" option under the subsurf modifier doesn't stop the issue from happening. So, not sure if that's the cause either.

Bastien Montagne commented

2015-08-12 14:20:06 +02:00

Added subscribers: @Sergey, @ideasman42, @mont29

Bastien Montagne commented

2015-08-12 14:20:06 +02:00

OK, so do not really understand why, but probably caused by recent looptri changes or subsurf changes, rna_ParticleSystem_uv_on_emitter() gets a NULL mtface data, which is not supposed to happen. This probably means DM_DIRTY_TESS_CDLAYERS is improperly cleared somewhere (or lack being set), but this code is rather hairy, @ideasman42, @Sergey will let you investigate further here, you probably can find the culprit much quicker than me.

OK, so do not really understand why, but probably caused by recent looptri changes or subsurf changes, `rna_ParticleSystem_uv_on_emitter()` gets a NULL mtface data, which is not supposed to happen. This probably means `DM_DIRTY_TESS_CDLAYERS` is improperly cleared somewhere (or lack being set), but this code is rather hairy, @ideasman42, @Sergey will let you investigate further here, you probably can find the culprit much quicker than me.

Bastien Montagne changed title from ~~Segfault when using any texture in strand shader~~ to Segfault (missing MTFace cdlayer from SubSurf DM).

2015-08-12 14:21:26 +02:00

Zauber Paracelsus commented

2015-08-16 15:59:00 +02:00

This issue seems to still be occuring as of build 19cc75d

This issue seems to still be occuring as of build 19cc75d

Campbell Barton commented

2015-08-18 08:54:14 +02:00

Changed status from 'Open' to: 'Resolved'

Campbell Barton closed this issue

2015-08-18 08:54:14 +02:00

Campbell Barton self-assigned this 2015-08-18 08:54:14 +02:00

Campbell Barton commented

2015-08-18 08:54:14 +02:00

this has been fixed - tested 92fe4e52fd which is working.

this has been fixed - tested 92fe4e52fd which is working.

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Segfault (missing MTFace cdlayer from SubSurf DM). #45749