Hair dynamics still not running properly in 2.77. #47703

New Issue

Rhys · 2016-03-06T19:55:17+01:00

Rhys commented

2016-03-06 19:55:17 +01:00

System Information
Windows 7 32 bit AMD Radeon HD 5700

Blender Version
Broken: ( blender-2.77-rc2-windows32 )
Worked: ( blender-2.73a-windows32 )

Problem :
Running and caching Hair dynamics: Still appears to be broken in 2.77-rc2.

Description :
I had heard from The Blender Cloud that the long running hair particle bugs that have been there in the last few Blender releases have been fixed for 2.77.
I’ve just been running my own tests with Blender 2.77 RC2 using a previously very stable rig and hair set up. Hair dynamics for simulation and caching still appears to be badly broken. At least in the version I’m running now.

It seems to on average only get to a minimum of 3 frames in a very simple scene with me before crashing ( Blender just vanishing ) Before it gets there the dynamics are all over the place, just pointing in all different directions and penetrating the mesh constantly. It seems to take a very long time to run and cache those few frames as well with Blender totally freezing and seeming to struggle for awhile on each frame.

Extra Notes:

I’m unclear if any hair setups for 2.77 need to be totally re-built from scratch to work for the new release ?
The rig set up and file I’m testing was very, very stable right up until 2.74. The last stable version I found to use for any hair simulation and caching is 2.73a which is the version I still use now for any work like this. Everything in this version and the one's previous to it have always been extremely stable and fast to simulate and cache in.

Please let me know if a scene file is necessary and I'll try to get one together. This file is within a project set up using a linked in rig. Although based on the experience's of trying to use recent past versions and the previous stability of the file the issue looks like it probably would be quite universal. I've not had time yet to try and create a new file totally from scratch from within Blender 2.77 but will try to set up a simple hairy sphere or something to test next.

**System Information** Windows 7 32 bit AMD Radeon HD 5700 **Blender Version** Broken: ( blender-2.77-rc2-windows32 ) Worked: ( blender-2.73a-windows32 ) Problem : Running and caching Hair dynamics: Still appears to be broken in 2.77-rc2. Description : I had heard from The Blender Cloud that the long running hair particle bugs that have been there in the last few Blender releases have been fixed for 2.77. I’ve just been running my own tests with Blender 2.77 RC2 using a previously very stable rig and hair set up. Hair dynamics for simulation and caching still appears to be badly broken. At least in the version I’m running now. It seems to on average only get to a minimum of 3 frames in a very simple scene with me before crashing ( Blender just vanishing ) Before it gets there the dynamics are all over the place, just pointing in all different directions and penetrating the mesh constantly. It seems to take a very long time to run and cache those few frames as well with Blender totally freezing and seeming to struggle for awhile on each frame. Extra Notes: I’m unclear if any hair setups for 2.77 need to be totally re-built from scratch to work for the new release ? The rig set up and file I’m testing was very, very stable right up until 2.74. The last stable version I found to use for any hair simulation and caching is 2.73a which is the version I still use now for any work like this. Everything in this version and the one's previous to it have always been extremely stable and fast to simulate and cache in. Please let me know if a scene file is necessary and I'll try to get one together. This file is within a project set up using a linked in rig. Although based on the experience's of trying to use recent past versions and the previous stability of the file the issue looks like it probably would be quite universal. I've not had time yet to try and create a new file totally from scratch from within Blender 2.77 but will try to set up a simple hairy sphere or something to test next. ![Hair_BlendTest2.77_RC2Crop.jpg](https://archive.blender.org/developer/F288838/Hair_BlendTest2.77_RC2Crop.jpg)

Rhys commented

2016-03-06 19:55:17 +01:00

Changed status to: 'Open'

Rhys self-assigned this 2016-03-06 19:55:17 +01:00

Rhys commented

2016-03-06 19:55:17 +01:00

Added subscriber: @RhysGriffin

Rhys removed their assignment 2016-03-06 19:56:02 +01:00

ronan ducluzeau commented

2016-03-07 16:33:28 +01:00

Added subscriber: @zeauro

ronan ducluzeau commented

2016-03-07 16:33:28 +01:00

For Cosmos Laundromat, basics of hair dynamics were modified to give a better result.
These changes were introduced in 2.74 release.
http://wiki.blender.org/index.php/Dev:Ref/Release_Notes/2.74/Particles#Hair_Dynamics

It is probably the reason why your pre-2.74 set-up does not work anymore.

Currently, volumetric calculations are based on a volumetric grid.
Your set-up is probably at a scale too high for defaults.
If Voxel Grid Cell Size parameter is ridiculously small compared to your character size; it is not surprizing that too many calculations are slowing down computer.

I hope that 2.74 release notes would be sufficient to help you to create a post-2.74 stable set-up.

For Cosmos Laundromat, basics of hair dynamics were modified to give a better result. These changes were introduced in 2.74 release. http://wiki.blender.org/index.php/Dev:Ref/Release_Notes/2.74/Particles#Hair_Dynamics It is probably the reason why your pre-2.74 set-up does not work anymore. Currently, volumetric calculations are based on a volumetric grid. Your set-up is probably at a scale too high for defaults. If Voxel Grid Cell Size parameter is ridiculously small compared to your character size; it is not surprizing that too many calculations are slowing down computer. I hope that 2.74 release notes would be sufficient to help you to create a post-2.74 stable set-up.

Sergey Sharybin commented

2016-03-08 11:10:23 +01:00

Added subscriber: @Sergey

Sergey Sharybin commented

2016-03-08 11:10:23 +01:00

Changed status from 'Open' to: 'Archived'

Sergey Sharybin closed this issue

2016-03-08 11:10:23 +01:00

Sergey Sharybin self-assigned this 2016-03-08 11:10:23 +01:00

Sergey Sharybin commented

2016-03-08 11:10:23 +01:00

Hair dynamics is very fragile area, while we were working on making solver more stable it might have introduced regression changes. This area is a real subject for re-code for 2.8x series. Current system is not really repairable, unfortunately.

Rhys commented

2016-03-09 12:01:57 +01:00

Thank you both so much for getting back on this so quickly in such a busy time.
This was an attempted bug report and not in any way a criticism and I think the work you are all doing is just fantastic.

I’ll look into the 2.74 release notes more closely and attempt to get some more tests done as soon as I have some spare time.
It does sound like things are still not very stable possibly ? I’m still not clear if I need to create a new hair system from scratch or just reapply the dynamics. The later versions of Blender run previously cached files with no problem at all so perhaps its just needing to set up new dynamics on any older hair set ups.

I was prompted to post this up because this issue just keeps coming up again and again on the forums and there does seem to still be a very great deal of confusion around it. Especially what is actually working and what might still be broken. That there had ever been problems recently is still not widely known and people seem to have spent many hours thinking it’s user error on their part.
I had no idea anything had been recently wrong until after I posted a question to the Blender Podcast.

Thank you both so much for getting back on this so quickly in such a busy time. This was an attempted bug report and not in any way a criticism and I think the work you are all doing is just fantastic. I’ll look into the 2.74 release notes more closely and attempt to get some more tests done as soon as I have some spare time. It does sound like things are still not very stable possibly ? I’m still not clear if I need to create a new hair system from scratch or just reapply the dynamics. The later versions of Blender run previously cached files with no problem at all so perhaps its just needing to set up new dynamics on any older hair set ups. I was prompted to post this up because this issue just keeps coming up again and again on the forums and there does seem to still be a very great deal of confusion around it. Especially what is actually working and what might still be broken. That there had ever been problems recently is still not widely known and people seem to have spent many hours thinking it’s user error on their part. I had no idea anything had been recently wrong until after I posted a question to the Blender Podcast.

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Hair dynamics still not running properly in 2.77. #47703