Alembic: low performance playback when keyframing object visibility #71740

Closed
opened 2019-11-21 20:46:25 +01:00 by Cenek Strichel · 14 comments

System Information
Operating system: Windows-10-10.0.18362 64 Bits
Graphics card: GeForce GTX 1080 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 441.20

Blender Version
Broken: version: 2.81 (sub 16), branch: master, commit date: 2019-11-20 14:27, hash: 26bd5ebd42
Worked: 2.80

Short description of error
I just opened my current project and playback dropped from 40fps (in Blender 2.80) to 13fps (in 2.81). I found that problem is with hidden animated (or drivered) object. If you animate (or drive) viewport visibility, it take performance similar to showed this object.

Exact steps for others to reproduce the error

  1. open scene
  2. be sure that *.abc is linked
  3. Play it with 2.80 and 2.81 and compare the FPS (33 resp. 11 FPS)

You can try it with this scene:
playback.blend
playback.abc

**System Information** Operating system: Windows-10-10.0.18362 64 Bits Graphics card: GeForce GTX 1080 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 441.20 **Blender Version** Broken: version: 2.81 (sub 16), branch: master, commit date: 2019-11-20 14:27, hash: `26bd5ebd42` Worked: 2.80 **Short description of error** I just opened my current project and playback dropped from 40fps (in Blender 2.80) to 13fps (in 2.81). I found that problem is with hidden animated (or drivered) object. If you animate (or drive) viewport visibility, it take performance similar to showed this object. **Exact steps for others to reproduce the error** 1) open scene 2) be sure that *.abc is linked 3) Play it with 2.80 and 2.81 and compare the FPS (33 resp. 11 FPS) You can try it with this scene: [playback.blend](https://archive.blender.org/developer/F8152401/playback.blend) [playback.abc](https://archive.blender.org/developer/F8152440/playback.abc)
Author

Added subscriber: @Cenda

Added subscriber: @Cenda
Author

Hello, any news with this? I would like to use 2.81 in my current project, but I can not, because performance is really bad.

Hello, any news with this? I would like to use 2.81 in my current project, but I can not, because performance is really bad.
Author

btw. problem is not related to Alembic, even I use some character rig, it take many frames when it is hidden.

btw. problem is not related to Alembic, even I use some character rig, it take many frames when it is hidden.
Member

Added subscriber: @JacquesLucke

Added subscriber: @JacquesLucke
Member

Changed status from 'Needs Triage' to: 'Needs User Info'

Changed status from 'Needs Triage' to: 'Needs User Info'
Member

If it is not related to alembic, could you then prepare a new simpler example to reproduce the issue?

If it is not related to alembic, could you then prepare a new simpler example to reproduce the issue?
Author

Just tried reproduce it without alembic, but it looks ok. So sorry problem is only with hidden alembic.

Just tried reproduce it without alembic, but it looks ok. So sorry problem is only with hidden alembic.
Author

for workaround I turned off visibility in the viewport in source file:
image.png

for workaround I turned off visibility in the viewport in source file: ![image.png](https://archive.blender.org/developer/F8266047/image.png)

Changed status from 'Needs User Info' to: 'Needs Developer To Reproduce'

Changed status from 'Needs User Info' to: 'Needs Developer To Reproduce'

Added subscriber: @dr.sybren

Added subscriber: @dr.sybren
Sybren A. Stüvel self-assigned this 2020-01-23 11:47:46 +01:00

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

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

This seems to be related to the keyframe animation on the viewport visibility of the objects. If I remove those FCurves, the performance is good (40-ish FPS on my machine). When the viewport visibility is keyframed, performance drops to 12-ish FPS on my machine.

I can also confirm that Blender 2.80 with the FCurves still there has the same performance as current 2.82 (1f6ab32196) with the FCurves removed.

This seems to be related to the keyframe animation on the viewport visibility of the objects. If I remove those FCurves, the performance is good (40-ish FPS on my machine). When the viewport visibility is keyframed, performance drops to 12-ish FPS on my machine. I can also confirm that Blender 2.80 with the FCurves still there has the same performance as current 2.82 (1f6ab32196) with the FCurves removed.
Sybren A. Stüvel changed title from Low performance playback to Alembic: low performance playback when keyframing object visibility 2020-01-23 11:49:52 +01:00

Changed status from 'Confirmed' to: 'Archived'

Changed status from 'Confirmed' to: 'Archived'

The slower performance is due to the new mesh normals handling introduced in e9c149d911. Mesh normals from Alembic were previously ignored by Blender; loading & handling them properly now takes time. This is to be expected. If smooth shading is good enough, and more detailed normals aren't necessary, export the Alembic without mesh normals and it should go back to the old performance.

The effect of animated visibility on modifier evaluation is a known limitation of the current Blender architecture. This is commented on in DepsgraphBuilder::need_pull_base_into_graph(), which determines what is to be evaluated and what isn't:

Since we don't support dynamic changes in dependency graph topology and all visible objects are to be part of dependency graph, we pull all objects which has animated visibility.

As a workaround you could put a driver on the viewport visibility and let it target the modifier enabled flag (the opposite is harder to do due to the visibility being stored per-object-per-viewlayer layer and not just per-object).

I'm closing this as a known issue (the status "Invalid" only indicates "closed but not resolved"; your remark that performance has gone down is still valid) as this is a limitation of the current design, and not a bug in Blender as such.

The slower performance is due to the new mesh normals handling introduced in e9c149d911. Mesh normals from Alembic were previously ignored by Blender; loading & handling them properly now takes time. This is to be expected. If smooth shading is good enough, and more detailed normals aren't necessary, export the Alembic without mesh normals and it should go back to the old performance. The effect of animated visibility on modifier evaluation is a known limitation of the current Blender architecture. This is commented on in [DepsgraphBuilder::need_pull_base_into_graph()](https://developer.blender.org/diffusion/B/browse/master/source/blender/depsgraph/intern/builder/deg_builder.cc$96), which determines what is to be evaluated and what isn't: > Since we don't support dynamic changes in dependency graph topology and all visible objects are to be part of dependency graph, we pull all objects which has animated visibility. As a workaround you could put a driver on the viewport visibility and let it target the modifier enabled flag (the opposite is harder to do due to the visibility being stored per-object-per-viewlayer layer and not just per-object). I'm closing this as a known issue (the status "Invalid" only indicates "closed but not resolved"; your remark that performance has gone down is still valid) as this is a limitation of the current design, and not a bug in Blender as such.
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Reference: blender/blender#71740
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