.bphys cache never writes particle size #65467

New Issue

Atomic · 2019-06-04T00:00:16+02:00

Atomic commented

2019-06-04 00:00:16 +02:00

System Information
Operating system:Windows
Graphics card:gtx660

Blender Version
Broken: 2.79 probably 2.8 too.

Short description of error
When reviewing the resulting .bphys cache files, the only thing written to the cache file is LOC and VEL.

Exact steps for others to reproduce the error
Based on the default startup or an attached .blend file (as simple as possible).
Bake the cache on the supplied BLEND file which will generate one particle.
Run the supplied python program to view the resulting one particle one frame cache.
There are only two pieces of data stored for the Newtonian particle, location and velocity.

Line #289 here:
https://developer.blender.org/diffusion/B/browse/master/source/blender/blenkernel/intern/pointcache.c
Shows the data type being assigned &pa->size could this be the problem? Does it need to be pa->size (remove the ampersand?)

27_make_one_particle.blend

**System Information** Operating system:Windows Graphics card:gtx660 **Blender Version** Broken: 2.79 probably 2.8 too. **Short description of error** When reviewing the resulting .bphys cache files, the only thing written to the cache file is LOC and VEL. **Exact steps for others to reproduce the error** Based on the default startup or an attached .blend file (as simple as possible). Bake the cache on the supplied BLEND file which will generate one particle. Run the supplied python program to view the resulting one particle one frame cache. There are only two pieces of data stored for the Newtonian particle, location and velocity. Line #289 here: https://developer.blender.org/diffusion/B/browse/master/source/blender/blenkernel/intern/pointcache.c Shows the data type being assigned *&pa->size* could this be the problem? Does it need to be *pa->size* (remove the ampersand?) [27_make_one_particle.blend](https://archive.blender.org/developer/F7085042/27_make_one_particle.blend)

Atomic commented

2019-06-04 00:00:16 +02:00

Added subscriber: @AtomP

Brecht Van Lommel commented

2019-06-04 00:31:58 +02:00

Added subscriber: @brecht

Brecht Van Lommel commented

2019-06-04 00:31:58 +02:00

It's true that the size is not written, BKE_ptcache_id_from_particles determines which data will be written. But have you found that this leads to a bug in Blender, does the size need to be written to correctly reconstruct the particles state? The existence of unused code by itself does not mean there is a bug.

It's true that the size is not written, `BKE_ptcache_id_from_particles` determines which data will be written. But have you found that this leads to a bug in Blender, does the size need to be written to correctly reconstruct the particles state? The existence of unused code by itself does not mean there is a bug.

Atomic commented

2019-06-05 16:19:09 +02:00

Size is also not read from the external .bphys file. So if I decide to write an external python script to generate a .bphys file,blender ignores the supplied size information. This does seem to be a bug.

Shouldn't Blender reliably relay the size information in the type def, if it is supplied by an external file?

Size is also not read from the external .bphys file. So if I decide to write an external python script to generate a .bphys file,blender ignores the supplied size information. This does seem to be a bug. Shouldn't Blender reliably relay the size information in the type def, if it is supplied by an external file?

Brecht Van Lommel commented

2019-06-05 17:48:48 +02:00

Changed status from 'Open' to: 'Archived'

Brecht Van Lommel closed this issue

2019-06-05 17:48:48 +02:00

Brecht Van Lommel self-assigned this 2019-06-05 17:48:48 +02:00

Brecht Van Lommel commented

2019-06-05 17:48:48 +02:00

While this would be useful, that's beyond a bugfix. The file format is defined by what it actually writes, not what disabled code could do. Even then this is an internal file format, not strictly defined by any specification.

The size is not something that is simulated, it is computed on the fly based on some settings. Changing that in the current particle code is messy, it's more likely to happen when we rewrite the particle system.

While this would be useful, that's beyond a bugfix. The file format is defined by what it actually writes, not what disabled code could do. Even then this is an internal file format, not strictly defined by any specification. The size is not something that is simulated, it is computed on the fly based on some settings. Changing that in the current particle code is messy, it's more likely to happen when we rewrite the particle system.

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.bphys cache never writes particle size #65467