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Hair Particles Not Displaying in Viewport
Closed, ResolvedPublic

Description

System Information
Operating system: Mac OSX El Capitan
Graphics card: NVIDIA GeForce GTX 670 4095 MB

Blender Version
Broken: 2.80, 2c21e3e35f30

Short description of error
• For hair particle systems, only a single strand is displayed in the viewport.
• Hair is rendered correctly in cycles, but not EEVEE.
• In some recent builds, particle edit mode works and displays parent particles correctly, but in current build switching to particle edit mode crashes Blender.
• Location of single strand displayed changes if number of particles is changed. Setting particle count to 0 crashes Blender.

Exact steps for others to reproduce the error
Default Cube > New Particle System > Change type to Hair > Default value is 1000: Only one strand displayed in viewport

Event Timeline

Sebastian Parborg (zeddb) triaged this task as Needs Information from User priority.

@William Reynish (billreynish) are you using OSX too?

I can not reproduce this on my side (linux). Is this still an issue for you guys with the latest build?

I think this might be related to T59426 (OSX too)

Still the same issue in the latest build, except for the last bullet point above (Blender no longer crashes if there are 0 hair particles).

On a whim, I decided to try today's build (08ab09cf04d9) on my wife's computer (an older Apple laptop), and it seems to work properly there, but it is still broken on my machine.

Another point to note that I missed in my initial description: when the particle type is switched to hair, the hair roots do not show up in the proper position on the mesh: they usually appear to be at the infinity point of either the x or y axis. The strand tip is in the right spot, leading to weird effects in the viewport. Hiding and then un-hiding the particle system fixes this problem. This happened on my wife's laptop as well, but with all the strands showing at the outset instead of just a single one.

Not to be a nag, but I really hope this can be fixed soon. Hair is a key part of my workflow and not being able to see it in the viewport at all in 2.8 has effectively kept me from using the new version thus far.

Sebastian Parborg (zeddb) raised the priority of this task from Needs Information from User to Normal.

Same happens to me. Hair shows but only up to a limit.
When you increase resolution or hair quantity (normal or children) it stops displaying or rendering.
It still renders on Cycles.

The same hair shows perfectly in 2.79 just by copying to it...
Latest 2.80 build here.

Same problem here. Only one hair visible in viewport. Particle edit mode, all hairs visible okay. Switch to Cycles, still one hair visible on wireframe and solid view. But Cycles rendered view shows hairs. Eevee doesn't.

Version: blender-2.80.0-git20190212.d3870471edd7-x86_64
Mac OSX El Capitan.

Dan Legnard (luxdan) reopened this task as Open.Mar 2 2019, 3:27 PM

Thank you for your hard work on this. Unfortunately, commit rB680c7209ecf7 hasn't resolved the issue as of today's build b5d87f802806. Hair particle behavior in the viewport remains the same, as described above.

The single visible hair strand does behave exactly as expected, following changes made in particle edit mode, casting a shadow in rendered mode, and displaying the correct viewport color. It would just be nice to be able to see the rest of them.

I did test Blender a few days ago with an ancient ATI card installed in the same machine, and hair particles worked, so it seems specific to Nvidia cards (in my case a GTX 670). I have tested with both OSXs default drivers and the most recent Nvidia Web Drivers and the same problem happens with both.

Soo it might be a problem with the buffer texture and not with the feedback transform.... I'll try to make yet another workaround for this, but I hate that we need to get creative just to workaround a driver bug.

Yeah, it's frustrating for sure, but I think I speak for a lot of us when I say we really appreciate your commitment to supporting Blender on Mac despite all of Apple's software issues.

I don't know if this is related to the same drawing code or if it's a separate bug, but I discovered that if you switch the particle type to hair, and then back to emitter, the emitter particle visualization disappears from the viewport (it works just fine when creating a new particle system).

Adding a dummy vertex attribute read fixed this issue on my machine (macOS 10.14.4 Beta, Radeon R​9 M295X). It seems like a driver bug triggered by shaders without vertex reads. I submitted the patch as D4490.

It sadly isn't solved on todays build... Will it come in another build?

Yes, the build including the fix ("March 11, 00:40:15 - 6fd11a21f5c5”) was released 8 hours ago.

Omg! Can't believe this is actually working now. Thanks a lot for your work!!! :)