Alembic Import does not apply MeshSequenceCache to all animated Meshes #81330

New Issue

soruh · 2020-09-30T17:07:55+02:00

soruh commented

2020-09-30 17:07:55 +02:00

System Information
Operating system: Linux 4.19.0-10-amd64 #1 SMP Debian 4.19.132-1 (2020-07-24) x86_64 GNU/Linux
Graphics card: NVIDIA Corporation GM107GL [Quadro K2200] (rev a2)

Blender Version
Broken: 2.90
Worked: N/A

Short description of error
I work with Alembic files which contain Meshes that may have constant geometry but varying vertex colors.
Importing an Alembic file containing such data only creates a MeshSequenceCache on the Meshes that have geometry changes.
The missing Meshes are created and their first Frame is imported. Manually adding MeshSequenceCache modifiers with the correct object-paths to them yields the expected result.

It seems to me like there is some optimization that prevents the creation of MeshSequenceCache modifiers on Meshes with constant geometry without considering if they have other animated properties.

Exact steps for others to reproduce the error

Import the attached Alembic file using the "Import->Alembic (.abc)" operator.
Observe that the correct Objects have been created but that the MeshSequenceCache modifier has only been applied to "Contour1"
Optional:
Manually create a MeshSequenceCache modifier on one of the objects, add the alembic file as the source file and select the correct "Object Path" (The same as the name of the object).
Observe that the vertex colors on that object are now animated correctly.

t106c.abc

**System Information** Operating system: Linux 4.19.0-10-amd64 #1 SMP Debian 4.19.132-1 (2020-07-24) x86_64 GNU/Linux Graphics card: NVIDIA Corporation GM107GL [Quadro K2200] (rev a2) **Blender Version** Broken: 2.90 Worked: N/A **Short description of error** I work with Alembic files which contain Meshes that may have constant geometry but varying vertex colors. Importing an Alembic file containing such data only creates a `MeshSequenceCache` on the Meshes that have geometry changes. The missing Meshes are created and their first Frame is imported. Manually adding `MeshSequenceCache` modifiers with the correct object-paths to them yields the expected result. It seems to me like there is some optimization that prevents the creation of `MeshSequenceCache` modifiers on Meshes with constant geometry without considering if they have other animated properties. **Exact steps for others to reproduce the error** - Import the attached Alembic file using the "Import->Alembic (.abc)" operator. - Observe that the correct Objects have been created but that the `MeshSequenceCache` modifier has only been applied to "Contour1" Optional: - Manually create a `MeshSequenceCache` modifier on one of the objects, add the alembic file as the source file and select the correct "Object Path" (The same as the name of the object). - Observe that the vertex colors on that object are now animated correctly. [t106c.abc](https://archive.blender.org/developer/F8940547/t106c.abc)

soruh commented

2020-09-30 17:07:57 +02:00

Added subscriber: @soruh

Philipp Oeser commented

2020-09-30 19:01:55 +02:00

Added subscriber: @lichtwerk

Philipp Oeser commented

2020-09-30 19:01:55 +02:00

Changed status from 'Needs Triage' to: 'Confirmed'

Philipp Oeser self-assigned this 2020-09-30 19:01:55 +02:00

Philipp Oeser commented

2020-09-30 19:01:55 +02:00

Can confirm, think I have a fix for this, modifiers are now created correctly.
It is a bit hard to test, since it seems colors are not really changing much in your file, do you have another [simpler] one -- like a cube with drastically changing colors :)? -- I'll try to create one as well...

Can confirm, think I have a fix for this, modifiers are now created correctly. It is a bit hard to test, since it seems colors are not really changing much in your file, do you have another [simpler] one -- like a cube with drastically changing colors :)? -- I'll try to create one as well...

blender-admin commented

2020-09-30 19:07:03 +02:00

This issue was referenced by 449e6124b5

This issue was referenced by 449e6124b5f75f91c52d231f763868ef4ddc5f1e

Philipp Oeser commented

2020-09-30 19:29:41 +02:00

@soruh: So at this point you could try D9057 (if you build yourself), or provide a super obvious test alembic, so I could check this is really working properly (since blender itself doesnt export animated vertex colors at all it seems).

@soruh: So at this point you could try [D9057](https://archive.blender.org/developer/D9057) (if you build yourself), or provide a super obvious test alembic, so I could check this is really working properly (since blender itself doesnt export animated vertex colors at all it seems).

soruh commented

2020-09-30 19:40:41 +02:00

Thank you very much for the quick response!

I'll try this tomorrow when I'm back at work and will attempt to make a more minimal example. (If I can figure out how to use the Alembic library again, their docs are pretty minimal)

Thank you very much for the quick response! I'll try this tomorrow when I'm back at work and will attempt to make a more minimal example. (If I can figure out how to use the Alembic library again, their docs are pretty minimal)

Philipp Oeser commented

2020-10-01 09:27:41 +02:00

Note that the missing writing of animated vertex colors already has its own task in #51488 (Alembic export animated vertex color exports only first frame vertex color)

Note that the missing **writing** of **animated** vertex colors already has its own task in #51488 (Alembic export animated vertex color exports only first frame vertex color)

soruh commented

2020-10-01 11:01:56 +02:00

Attached you will find two Alembic files which should be useful for testing.
I will now try compiling blender from source to confirm that the fix works for my use-case.

mesh_change.abc

static_mesh.abc

Attached you will find two Alembic files which should be useful for testing. I will now try compiling blender from source to confirm that the fix works for my use-case. [mesh_change.abc](https://archive.blender.org/developer/F8943351/mesh_change.abc) [static_mesh.abc](https://archive.blender.org/developer/F8943350/static_mesh.abc)

Philipp Oeser commented

2020-10-01 11:14:24 +02:00

Thx for these!

This is what I get with the patch (so I guess it is working):
#81330.webm

Thx for these! This is what I get with the patch (so I guess it is working): [#81330.webm](https://archive.blender.org/developer/F8943389/T81330.webm)

soruh commented

2020-10-01 11:15:23 +02:00

Yes that seems correct. Thank you very much!

soruh commented

2020-10-02 10:01:09 +02:00

I have build blender with the patch and can confirm that it works with my data.

Philipp Oeser commented

2020-10-07 11:00:44 +02:00

Changed status from 'Confirmed' to: 'Resolved'

Philipp Oeser closed this issue

2020-10-07 11:00:44 +02:00

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Alembic Import does not apply MeshSequenceCache to all animated Meshes #81330

Alembic Import does not apply `MeshSequenceCache` to all animated Meshes #81330