Cache of cloth simulation is not read by blender after reopening the file (pre-roll) #70631

New Issue

Michael George · 2019-10-08T11:07:47+02:00

Michael George commented

2019-10-08 11:07:47 +02:00

System Information
Operating system: Windows-10-10.0.10240 64 Bits
Graphics card: GeForce GT 710/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 390.65

Blender Version
Broken: version: 2.80 (sub 75), branch: master, commit date: 2019-07-29 14:47, hash: f6cb5f5449

Short description of error
I bake the cloth simulation. I see the blendcache_cloth folder. When I close and reopen the .blend file, the data in the cache folder is not read. When I go to the physics tab, I see the Delete Bake button. This means that blender recognizes that I baked the simulation before but the cloth plane is not animated.

Note 1 : For a small project, when I choose Automatically Pack into .blend it works but for some large project it doesn't work even after choosing Automatically Pack into .blend. Anyway, I wouldn't like to pack All because this will double the size of the texture, audio files, ...etc on my hard drive.

Note 2 : I also tried the method of exporting the cloth simulation as .mdd file. When I import this file again using File>Import, the cloth plane is animated but it is inserted in a very very far location from its original location. The solution is to use Mesh Cache modifier and to modify the axes and to clear all transformation.

Exact steps for others to reproduce the error

Download the attached .blend file.
Select the plane.
Go to the Physics tab to see the properties of the cloth simulation.
Click on "Delete Bake" if you find it.
You may reduce the End frame so that you don't bake the whole 500 frames. You can make it 100 or 200 depending on your computer's speed.
Click on "Bake" to bake the animation with the Disk Cache option enabled.
Save the file. Close blender. Re-open the file.
Try to play... No animation!

I wish if there was an option to enter the path or the location of the cache folder. Thank you for your support and for caring about our bug reports. That's really appreciated :)
cloth.blend

**System Information** Operating system: Windows-10-10.0.10240 64 Bits Graphics card: GeForce GT 710/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 390.65 **Blender Version** Broken: version: 2.80 (sub 75), branch: master, commit date: 2019-07-29 14:47, hash: `f6cb5f5449` **Short description of error** I bake the cloth simulation. I see the *blendcache_cloth* folder. When I close and reopen the .blend file, the data in the cache folder is not read. When I go to the physics tab, I see the *Delete Bake* button. This means that blender recognizes that I baked the simulation before but the cloth plane is not animated. Note 1 : For a small project, when I choose *Automatically Pack into .blend* it works but for some large project it doesn't work even after choosing *Automatically Pack into .blend*. Anyway, I wouldn't like to pack All because this will double the size of the texture, audio files, ...etc on my hard drive. Note 2 : I also tried the method of exporting the cloth simulation as .mdd file. When I import this file again using **File>Import**, the cloth plane is animated but it is inserted in a very very far location from its original location. The solution is to use Mesh Cache modifier and to modify the axes and to clear all transformation. **Exact steps for others to reproduce the error** 1. Download the attached .blend file. 2. Select the plane. 3. Go to the Physics tab to see the properties of the cloth simulation. 4. Click on "Delete Bake" if you find it. 5. You may reduce the End frame so that you don't bake the whole 500 frames. You can make it 100 or 200 depending on your computer's speed. 5. Click on "Bake" to bake the animation with the Disk Cache option enabled. 6. Save the file. Close blender. Re-open the file. 7. Try to play... No animation! I wish if there was an option to enter the path or the location of the cache folder. Thank you for your support and for caring about our bug reports. That's really appreciated :) [cloth.blend](https://archive.blender.org/developer/F7796370/cloth.blend)

Michael George commented

2019-10-08 11:07:47 +02:00

Added subscriber: @MikeBlenderLover

blender-admin commented

2019-10-08 11:07:47 +02:00

#91227 was marked as duplicate of this issue

Philipp Oeser commented

2019-10-09 18:25:31 +02:00

Added subscribers: @LucaRood-3, @Sergey, @brecht, @lichtwerk

Philipp Oeser commented

2019-10-09 18:25:31 +02:00

This is tied to the simulation having a negative start frame.

Afaics, these wont be read in correctly atm.
https://docs.blender.org/manual/en/latest/physics/baking.html

The simulation is only calculated for positive frames in between the Start and End frames of the Cache panel, whether you bake or not. So if you want a simulation that is longer than the default frame range you have to change the End frame.

Cloth did even have a "pre-roll" feature once, but that was removed also, see D877: Removed the cloth "pre-roll" feature.

The comment from the manual is not really correct either though, it seems you can do a pre-roll if you

cache to disk with negative frames [as you did in your file]
.bphys with negative frames will be written to disk [better back these up in a folder elsewhere]
the whole range wont be read in correctly, BUT
now set that file with a disk cache starting at 1 [not -12 as in your file], close blender
copy over the .bphys with the positive frames from the backup folder, reopen that file, seems to work...

To me this is highly confusing as well, I hope I am not misrepresenting how the workflow really is at the current state of blender?
CC @brecht [he was once involved in #33469], @LucaRood-3 , @Sergey or maybe [not sure who is doing sim at the studio?]?

Not sure how to handle the status of this report. Bug or not?

This is tied to the simulation having a negative start frame. Afaics, these wont be read in correctly atm. https://docs.blender.org/manual/en/latest/physics/baking.html > The simulation is only calculated for positive frames in between the Start and End frames of the Cache panel, whether you bake or not. So if you want a simulation that is longer than the default frame range you have to change the End frame. Cloth did even have a "pre-roll" feature once, but that was removed also, see [D877: Removed the cloth "pre-roll" feature.](https://archive.blender.org/developer/D877) The comment from the manual is not really correct either though, it seems you can do a pre-roll if you - cache to disk with negative frames [as you did in your file] - .bphys with negative frames will be written to disk [better back these up in a folder elsewhere] - the whole range wont be read in correctly, BUT - now set that file with a disk cache starting at 1 [not -12 as in your file], close blender - copy over the .bphys with the positive frames from the backup folder, reopen that file, seems to work... To me this is highly confusing as well, I hope I am not misrepresenting how the workflow really is at the current state of blender? CC @brecht [he was once involved in #33469], @LucaRood-3 , @Sergey or maybe [not sure who is doing sim at the studio?]? Not sure how to handle the status of this report. Bug or not?

Philipp Oeser changed title from ~~Chache of cloth simulation is not read by blender after reopening the file~~ to Cache of cloth simulation is not read by blender after reopening the file

2019-10-09 18:25:49 +02:00

Philipp Oeser changed title from ~~Cache of cloth simulation is not read by blender after reopening the file~~ to Cache of cloth simulation is not read by blender after reopening the file (pre-roll)

2019-10-09 18:26:17 +02:00

Michael George commented

2019-10-09 20:07:02 +02:00

Well, I didn't know that the pre-roll feature was removed as I'm a beginner. So, I think it's better to show a warning message when someone tries to bake while entering a negative value. For me, the best thing is to make this feature work again. I know there might be programming limitations but the more features the software has, the better it will be.

Thank you all for your support. Really appreciated :)

Well, I didn't know that the pre-roll feature was removed as I'm a beginner. So, I think it's better to show a warning message when someone tries to bake while entering a negative value. For me, the best thing is to make this feature work again. I know there might be programming limitations but the more features the software has, the better it will be. Thank you all for your support. Really appreciated :)

Richard Antalik commented

2020-01-14 18:06:46 +01:00

Changed status from 'Needs Developer To Reproduce' to: 'Confirmed'

Bastien Montagne commented

2020-01-15 16:23:54 +01:00

Added subscriber: @mont29

Bastien Montagne commented

2020-01-15 16:23:54 +01:00

Would consider that as a known issue for now, our current physics caching is known to be problematic in many aspects...

Luca Rood commented

2020-02-22 16:50:45 +01:00

Definitely a known issue. I believe the pointcache system should be removed in favour of a completely new solution.
I think it is relevant to mention here that I started working on an alternative to the pointcache some time ago. I don't have time to continue work on it right now, but the foundation is there.
It is publicly accessible on my gitlab: https://gitlab.com/LucaRood/OmniCache

Definitely a known issue. I believe the pointcache system should be removed in favour of a completely new solution. I think it is relevant to mention here that I started working on an alternative to the pointcache some time ago. I don't have time to continue work on it right now, but the foundation is there. It is publicly accessible on my gitlab: https://gitlab.com/LucaRood/OmniCache

Brecht Van Lommel commented

2020-02-24 22:18:10 +01:00

Added subscriber: @JacquesLucke

Brecht Van Lommel commented

2020-02-24 22:18:10 +01:00

@LucaRood-3 @JacquesLucke, caching is planned to be revisited and eventually become part of a new simulation datablock for all physics systems.
https://wiki.blender.org/wiki/Source/Nodes/UnifiedSimulationSystemProposal

@LucaRood-3 @JacquesLucke, caching is planned to be revisited and eventually become part of a new simulation datablock for all physics systems. https://wiki.blender.org/wiki/Source/Nodes/UnifiedSimulationSystemProposal

Gabriel Gomez commented

2020-04-28 22:16:10 +02:00

Added subscriber: @gabrign

Richard Antalik commented

2022-02-18 21:48:49 +01:00

Added subscribers: @AlexMelkin, @iss, @dave9828

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Cache of cloth simulation is not read by blender after reopening the file (pre-roll) #70631