Hair Particle System causes crash when Dynamic Baking is preformed, and edditing is attempted #44172

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jorgen · 2015-03-29T12:28:18+02:00

jorgen commented

2015-03-29 12:28:18 +02:00

System Information
Windows 7 Home Premium
GeForce GT 540M

Blender Version
Broken: 2.73a

By the way, i dont know if this is a Bug or something that is expected to happen. Thought it would not harm to report it anyway
If you go to [Particle Edit] after you enable [Hair Dynamics], you will see that blender will either crash, or run really really slowly.
Some times it just crashes right away, other times it gets into [Particle Edit], and i can rotate in the viewport just fine, but if i try to [Comb] the hair, then it gets stuck again.

Exact steps for others to reproduce the error
This can easily be reproduced:

Open up blender (Fresh)
Blender Internal / Cycles Render does not matter, it happens on both
Go to Particle system
Set Emition to Hair
Enable Hair Dynamics
Under Cache, click Bake
Go to Particle Edit

Blender should now either crash, or slow freez for a while. then if you get into particle edit, try to comb the hair.
Blender_Crash_Report.blend

**System Information** Windows 7 Home Premium GeForce GT 540M **Blender Version** Broken: 2.73a **By the way, i dont know if this is a Bug or something that is expected to happen. Thought it would not harm to report it anyway** If you go to [Particle Edit] after you enable [Hair Dynamics], you will see that blender will either crash, or run really really slowly. Some times it just crashes right away, other times it gets into [Particle Edit], and i can rotate in the viewport just fine, but if i try to [Comb] the hair, then it gets stuck again. **Exact steps for others to reproduce the error** This can easily be reproduced: * Open up blender (Fresh) * Blender Internal / Cycles Render does not matter, it happens on both * Go to Particle system * Set Emition to Hair * Enable Hair Dynamics * Under Cache, click Bake * Go to Particle Edit Blender should now either crash, or slow freez for a while. then if you get into particle edit, try to comb the hair. [Blender_Crash_Report.blend](https://archive.blender.org/developer/F156045/Blender_Crash_Report.blend)

jorgen commented

2015-03-29 12:28:18 +02:00

Changed status to: 'Open'

jorgen self-assigned this 2015-03-29 12:28:18 +02:00

jorgen commented

2015-03-29 12:28:18 +02:00

Added subscriber: @finalbarrage-2

jorgen was unassigned by Julian Eisel

2015-03-29 15:23:04 +02:00

Lukas Tönne was assigned by Julian Eisel

2015-03-29 15:23:04 +02:00

Julian Eisel commented

2015-03-29 15:23:04 +02:00

Added subscribers: @LukasTonne, @JulianEisel

Julian Eisel commented

2015-03-29 15:23:04 +02:00

For me it doesn't crash but it's reeeally slow. It also doesn't work better in 2.72 so I'm a bit afraid it's a more in deepth issue. Doesn't look like a memory issue, memory seems to be okay. Got ~13% CPU usage on my 8 threads machine, so I'd guess it just locks the main thread. If this is case this is definitely a todo.

@LukasTonne, what do you think? (We also better move this to the todo list if it's nothing you can look into soon, users should know that they can just press "Free Bake")

For me it doesn't crash but it's reeeally slow. It also doesn't work better in 2.72 so I'm a bit afraid it's a more in deepth issue. Doesn't look like a memory issue, memory seems to be okay. Got ~13% CPU usage on my 8 threads machine, so I'd guess it just locks the main thread. If this is case this is definitely a todo. @LukasTonne, what do you think? (We also better move this to the todo list if it's nothing you can look into soon, users should know that they can just press "Free Bake")

Lukas Tönne commented

2015-03-29 16:49:33 +02:00

The whole design here is totally unusable. Basically there are 2 modes of the "particle edit mode" (itself a misnomer already):

When the hair dynamics is not baked, it will enter the usual hair edit mode, i.e. you can do add, comb, cut etc. on hair strands. These strands are the static shapes that form the basis for bending and goal spring forces.
When the cache is in "baked" mode, the edit mode will instead use the "cache edit mode" as described above. This mode is not usable at all in it's current design, especially for hair strands. With regular particles it sort-of works by creating a path for each of the particles over time and allowing strand-like editing on these (note the difference between physical strand objects and interpolating point motion - using the same tool for both is only smart at first glance). With hair strands, however, the concept totally breaks down: it creates a new "time strand" for each of the hair vertices! With a bit of simple arithmetic one can see that the amount of data generated this way explodes and becomes too much to handle for any reasonable hardware. Even small amounts of hair also are not really editable due to the lack of visual detail anyway.

Long story short: this "feature" has to be removed.

The whole design here is totally unusable. Basically there are 2 modes of the "particle edit mode" (itself a misnomer already): * When the hair dynamics is not baked, it will enter the usual hair edit mode, i.e. you can do add, comb, cut etc. on hair strands. These strands are the static shapes that form the basis for bending and goal spring forces. * When the cache is in "baked" mode, the edit mode will instead use the "cache edit mode" as described above. This mode is not usable at all in it's current design, especially for hair strands. With regular particles it sort-of works by creating a path for each of the particles over time and allowing strand-like editing on these (note the difference between physical strand objects and interpolating point motion - using the same tool for both is only smart at first glance). With hair strands, however, the concept totally breaks down: it creates a new "time strand" for each of the hair vertices! With a bit of simple arithmetic one can see that the amount of data generated this way explodes and becomes too much to handle for any reasonable hardware. Even small amounts of hair also are not really editable due to the lack of visual detail anyway. Long story short: this "feature" has to be removed.

Lukas Tönne commented

2015-06-22 11:27:54 +02:00

Changed status from 'Open' to: 'Archived'

Lukas Tönne closed this issue

2015-06-22 11:27:54 +02:00

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Hair Particle System causes crash when Dynamic Baking is preformed, and edditing is attempted #44172