Bad frames importing Alembic file. #94013

New Issue

Valentin Bonhomme · 2021-12-13T11:32:01+01:00

Valentin Bonhomme commented

2021-12-13 11:32:01 +01:00

System Information
Operating system: Linux-5.4.0-91-generic-x86_64-with-glibc2.31 64 Bits
Graphics card: GeForce RTX 2080 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 460.91.03

Blender Version
Broken: version: 3.0.0, branch: master, commit date: 2021-12-02 18:35, hash: f1cca30557
Broken: version: 3.1.0 Alpha, branch master, commit date: 2021-12-13 00:03
Broken: version: 3.0.0 Beta

Worked: version: 2.92.0, branch Master, commit date: 2021-02-24 16:25 hash: '02948a2ca444'

Short description of error
Some frames of my Alembic file appear 'broken' with Blender 3 and works well with Blender 2.92. See the figure below.

My sequence is composed by blocks of frames (frames sharing the same topology). It looks like problematic frames are always the last frames of a block.
If I change the MeshSequenceCache Frame Offset (to 0.1 by example), frames are still broken but differently.

It's only appear with some alembic files I have, not all.

Exact steps for others to reproduce the error
compo_export_short.abc
To reproduce the problem please create a new project, set the Frame Rate to 30 fps. Import the 'compo_export_short.abc' file that I provide.
You can see the problem at frames 6, 24 and 47.
(There is some empty frames at the end of the file, it's normal.)

Thanks !

**System Information** Operating system: Linux-5.4.0-91-generic-x86_64-with-glibc2.31 64 Bits Graphics card: GeForce RTX 2080 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 460.91.03 **Blender Version** Broken: version: 3.0.0, branch: master, commit date: 2021-12-02 18:35, hash: `f1cca30557` Broken: version: 3.1.0 Alpha, branch master, commit date: 2021-12-13 00:03 Broken: version: 3.0.0 Beta Worked: version: 2.92.0, branch Master, commit date: 2021-02-24 16:25 hash: '02948a2ca444' **Short description of error** Some frames of my Alembic file appear 'broken' with Blender 3 and works well with Blender 2.92. See the figure below. My sequence is composed by blocks of frames (frames sharing the same topology). It looks like problematic frames are always the last frames of a block. If I change the MeshSequenceCache Frame Offset (to 0.1 by example), frames are still broken but differently. It's only appear with some alembic files I have, not all. ![Screenshot from 2021-12-13 11-17-25.png](https://archive.blender.org/developer/F12736630/Screenshot_from_2021-12-13_11-17-25.png) **Exact steps for others to reproduce the error** [compo_export_short.abc](https://archive.blender.org/developer/F12736613/compo_export_short.abc) To reproduce the problem please create a new project, set the Frame Rate to 30 fps. Import the 'compo_export_short.abc' file that I provide. You can see the problem at frames 6, 24 and 47. (There is some empty frames at the end of the file, it's normal.) Thanks !

Valentin Bonhomme commented

2021-12-13 11:32:01 +01:00

Added subscriber: @ValentinBonhomme

Philipp Oeser commented

2021-12-15 13:41:05 +01:00

Added subscriber: @lichtwerk

Philipp Oeser commented

2021-12-15 13:41:05 +01:00

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

Philipp Oeser closed this issue

2021-12-15 13:41:05 +01:00

Philipp Oeser commented

2021-12-15 13:41:05 +01:00

Sometimes this can happen if the mesh has constant number of vertices but still changes vertex order somehow.
The culprit then is the Vertex Interpolation option on the modifier.
While often this is a good thing to have (and it is ON by default) this option can cause problems.

See bab2260b59

So in your case, the solution is to turn Vertex Interpolation OFF.

This is not a bug however, will close.
(of course feel free to comment again if issues persist, we can always reopen in such case...)

Sometimes this can happen if the mesh has constant number of vertices but still changes vertex order somehow. The culprit then is the `Vertex Interpolation` option on the modifier. While often this is a good thing to have (and it is ON by default) this option *can* cause problems. See bab2260b59 So in your case, the solution is to turn `Vertex Interpolation` OFF. This is not a bug however, will close. (of course feel free to comment again if issues persist, we can always reopen in such case...)

Valentin Bonhomme commented

2021-12-16 13:41:45 +01:00

Thanks a lot for the answer ! It solved indeed my problem.

Just to let you know, this option doesn't appear in the Mesh Sequence Cache Modifier documentation .

Thanks a lot for the answer ! It solved indeed my problem. Just to let you know, this option doesn't appear in the [Mesh Sequence Cache Modifier documentation ](https://docs.blender.org/manual/en/3.0/modeling/modifiers/modify/mesh_sequence_cache.html#).

Philipp Oeser commented

2021-12-16 13:48:56 +01:00

Added subscriber: @Blendify

Philipp Oeser commented

2021-12-16 13:48:56 +01:00

In #94013#1273791, @ValentinBonhomme wrote:
Thanks a lot for the answer ! It solved indeed my problem.

Just to let you know, this option doesn't appear in the Mesh Sequence Cache Modifier documentation .

CC @Blendify reg. manual

> In #94013#1273791, @ValentinBonhomme wrote: > Thanks a lot for the answer ! It solved indeed my problem. > > Just to let you know, this option doesn't appear in the [Mesh Sequence Cache Modifier documentation ](https://docs.blender.org/manual/en/3.0/modeling/modifiers/modify/mesh_sequence_cache.html#). CC @Blendify reg. manual

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Bad frames importing Alembic file. #94013