"Copy Location" Constraint using "Vertex Group" seem to not work when Simulation Nodes are Cached to Disk. #113538

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opened 2023-10-11 12:19:02 +02:00 by Daniel Vesterbæk Jensen · 6 comments

Daniel Vesterbæk Jensen commented

2023-10-11 12:19:02 +02:00

System Information
Operating system: Windows-10-10.0.19045-SP0 64 Bits
Graphics card: NVIDIA GeForce RTX 4090/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 536.23

Blender Version
Broken: version: 3.6.4, branch: blender-v3.6-release, commit date: 2023-09-25 13:24, hash: 21bfc5e7fe3f
Worked: None, that I am aware of.

Short description of error
Having a secondary object "copy location" of a primary object with a "Vertex Group" using the constraint works fine when played back in the viewport. The secondary obj follows the primary obj - also when baked. However, after baking the cache to disk and re-opening the file, the primary obj keeps its motion, but the secondary obj does not. It acts as if the constraint was disabled.

The same happens when using "Vertex Parenting" instead of a "copy location constraint"

Exact steps for others to reproduce the error

Open up one of the two files.
Bake the Simulation Nodes on the object "Cube" -> The object "Circle", should follow the "Cube".
Save, Close and Open the file
The "Cube" will still have its baked motion, but the "Circle" will be static at the scene origin.

Tested in Blender 4.0 Beta and 3.6.5 RC with same result.

**System Information** Operating system: Windows-10-10.0.19045-SP0 64 Bits Graphics card: NVIDIA GeForce RTX 4090/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 536.23 **Blender Version** Broken: version: 3.6.4, branch: blender-v3.6-release, commit date: 2023-09-25 13:24, hash: `21bfc5e7fe3f` Worked: None, that I am aware of. **Short description of error** Having a secondary object "copy location" of a primary object with a "Vertex Group" using the constraint works fine when played back in the viewport. The secondary obj follows the primary obj - also when baked. However, after baking the cache to disk and re-opening the file, the primary obj keeps its motion, but the secondary obj does not. It acts as if the constraint was disabled. The same happens when using "Vertex Parenting" instead of a "copy location constraint" **Exact steps for others to reproduce the error** - Open up one of the two files. - Bake the Simulation Nodes on the object "Cube" -> The object "Circle", should follow the "Cube". - Save, Close and Open the file - The "Cube" will still have its baked motion, but the "Circle" will be static at the scene origin. Tested in Blender 4.0 Beta and 3.6.5 RC with same result.

simple_cache_vertexParenting.blend

886 KiB

simple_cache_vertexGroup.blend

886 KiB

Daniel Vesterbæk Jensen added the

labels 2023-10-11 12:19:03 +02:00

Philipp Oeser commented

2023-10-11 12:25:31 +02:00

Member

Can confirm

Can confirm

Philipp Oeser added

Nodes & Physics

Animation & Rigging

and removed

labels 2023-10-11 12:26:34 +02:00

Philipp Oeser commented

2023-10-11 12:52:55 +02:00

Member

It is also not working when using the cached vertexgroup for something else (in this case just used in a displace modifier)

It is also not working when using the cached vertexgroup for something else (in this case just used in a displace modifier)

simple_cache_vertexGroup2.blend

904 KiB

Iliya Katushenock added the

label 2023-10-11 12:57:41 +02:00

Philipp Oeser commented

2023-10-11 12:59:00 +02:00

Member

Asked in chat and "vertex groups will be converted to proper attributes in the simulation cache. Would be nice if that was documented somewhere indeed"

Asked in chat and "vertex groups will be converted to proper attributes in the simulation cache. Would be nice if that was documented somewhere indeed"

Daniel Vesterbæk Jensen commented

2023-10-11 14:40:30 +02:00

Author

I don't know if it's related, it seems that undo will in the same way remove the motion of the secondary obj.

Steps:

Open the file and bake cache for the "Cube"
Play back some frames
Hit undo, current frame jumps back to 1
Motion of the "Cube" stays the same (with baked cache), but the "Circle" looses its motion

I don't know if it's related, it seems that undo will in the same way remove the motion of the secondary obj. Steps: - Open the file and bake cache for the "Cube" - Play back some frames - Hit undo, current frame jumps back to 1 - Motion of the "Cube" stays the same (with baked cache), but the "Circle" looses its motion

simple_cache_vertexGroup_undo.blend

887 KiB

Sven-Giera commented

2023-12-04 18:14:00 +01:00

I have the same issue. Would be awesome if it was fixed as soon as possible!

I have the same issue. Would be awesome if it was fixed as soon as possible!

MKRelax commented

2023-12-29 17:35:40 +01:00

Can confirm that this is still a problem in Blender 4.0.2. After baking Simulation Zones and reloading the file, all "Track To" and "Copy Location" constraints stop working. I have many simulation node setups that move vertices to be tracked by bones or objects (by vertex group).
This bug prevents me from rendering any scene that uses this.

A screencast and .blend file have been added as attachments.

Can confirm that this is still a problem in Blender 4.0.2. After baking Simulation Zones and reloading the file, all "Track To" and "Copy Location" constraints stop working. I have many simulation node setups that move vertices to be tracked by bones or objects (by vertex group). This bug prevents me from rendering any scene that uses this. A screencast and .blend file have been added as attachments.

Track Vertex.blend

806 KiB

_ Track Vertex [V__Development_Blender_Objects_[Bugs]_track-gn-vertex-group_Track Vertex.blend] - Blender 4.0 2023-12-29 17-20-01.mp4

19 MiB

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Reference: blender/blender#113538

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