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Mask modifier followed by hair particles causes crash on render (cycles)
Closed, ResolvedPublic

Description

System Information
GNU Linux 64 bit - fedora 20/ Intel CPU / nvidia GPU

Blender Version
Broken: 0e324b1
Worked: 2.70a

Short description of error

On the selected mesh is a mask modifier that hides the entire mesh, follwed by a particle system,
On Render, you get lots of the following message:
NO CD_ORIGSPACE, error out of range
Followed by a segfault
In 2.70 you get the same error, but no crash

Exact steps for others to reproduce the error

  1. Download the file
  2. Open it in git master
  3. press render
  4. Crash!
  5. try again, this time disable one of the two modifiers
  6. No crash

Event Timeline

bassam kurdali (bassamk) raised the priority of this task from to 90.
bassam kurdali (bassamk) updated the task description. (Show Details)
bassam kurdali (bassamk) edited a custom field.

I'm getting:

	NO CD_ORIGSPACE, error out of range
BLI_assert failed: /home/kevin/src/blender-git/blender/source/blender/blenkernel/intern/DerivedMesh.c:695, DM_get_tessface_data(), at 'index >= 0 && index < dm->getNumTessFaces(dm)'

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7fffccff9700 (LWP 10715)]
0x00000000025ea9a4 in psys_interpolate_uvs (tface=0x0, quad=0, w=0x7dad598, 
    uvco=0x7fffccff4bd0)
    at /home/kevin/src/blender-git/blender/source/blender/blenkernel/intern/particle.c:1549
1549               float v10 = tface->uv[0][0];

Well, it is a crash but not annoying for usability.
It is known that modifiers messing up geometry are affecting particles stability.

Use Modifier Stack option does not seem to work for this modifier.

There is no crash with mask modifier after particles.
Particles have its own renderability properties to avoid to render emitter or particles.
Material textures can be used instead of vertex groups to manage their visibility.

doesn't work shouldn't mean crash! crash is not an acceptible way for program to behave.

and it does affect usability, sorry to say. complex workarounds (need two meshes, one with mask, one with particles, animated at the same time) are just that: workarounds.

Bastien Montagne (mont29) lowered the priority of this task from 90 to Normal.Jul 19 2014, 4:58 PM

Should not crash, in any case…

There seems to be two different issues here - the error message about missing CD_ORIGSPACE only happens when mask modifier removes all geometry.

The crash however happens whether there is geometry or not, and seems specific to Cycles.

Not adding Cycles, since I suspect it’s in fact in RNA that crash happens.

I agree that a crash is an issue
No, you don't need two mesh.
You want to hide emitter : just uncheck emitter option particle system properties.
You want to hide hairs : just uncheck Cycles hair checkbox.

I am not talking about workarounds. I am just reminding what is perfectly obvious in particle properties but that every user ignores.
THE DAMNED RENDER PANEL !

You want a masking through an animated texture. Use same animated texture in both materials.

I forgot that you can also put your vertex group in Vertex Groups panel to control length of particles. length=0 means invisible particles.

You are not supposed to use mask modifier for that at all, in current particle system design.
It never worked perfectly.
Mask modifier is known to not be useable in several cases like sculpt mode since years too.
There are problems with modifiers and particles since years.

I am just realistic. Particles new system is expected since years, now.
But what you want to achieve is doable, now by respecting old system concepts.

Previous blend solved by using vertex groups panel.

right. It doesn't work. That is a problem. Not ideal,but also not something to defend - future designs of particles will eliminate such problems as is already being coded. I've already worked around this in my files.

Also: Not what I am reporting here, aka, not the bug The bug is the crash. period. end of story. Blender shouldn't crash because some buttons were pressed. This becomes incredibly hard to debug in a big project with lots of artists (which is where this file is from)

Thanks for the solution though; I appreciate you trying to help. Just please tone down the rhetoric. You're doing a good job confirming the bugs and helping, thanks.

Bastien Montagne (mont29) changed the task status from Unknown Status to Resolved.Jul 20 2014, 12:58 AM

Closed by commit rB3ca78a40e8b9.