Linked Instances Across Scenes have unreliable updates when editing their common mesh data. #91996

New Issue

daniellapalme@gmail.com · 2021-10-07T05:35:33+02:00

2021-10-07 05:35:33 +02:00

Broken: 2.93.4 LTS;
Broken: master

Short description of error
With two different objects in two different scenes sharing a same obdata Mesh, editing the mesh in one of the scene can fail to properly update object in the other scene.

Exact steps for others to reproduce the error

Open attached file.
Go to scene 2.
Switch to Edit mode.
Assign the red material (first slot) to the cube in edit mode.
Switch back to Object mode.
Go to Scene 1, the Cube in Scene one still uses the second slot material (green).

Switch to edit mode and back, now the cube is shown with expected first material slot (red) as well.

NOTE: If you replace step 4 by a mesh geometry editing (e.g. rotate the mesh in Edit mode), in current master there is the same missing update issue in Scene 1, but in 2.93LTS it is properly updated... Regression introduced by 51568030e9.

Example.blend

Original report

System Information
Operating system: Windows-10-10.0.22000-SP0 64 Bits
Graphics card: NVIDIA GeForce GTX 680/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 472.12

Blender Version
Broken: version: 2.93.0, branch: master, commit date: 2021-06-02 11:21, hash: 84da05a8b8

Short description of error
If you link an instanced object to another scene, having it's material link to object, it can have a different material from the non-instance. However upon saving and re-opening the scene, the instance's material will revert to that of the non-instance.

Exact steps for others to reproduce the error

Open attached file or
- Take the default cube and assign a material to it. In the viewport display settings assign a color for the material, this will give feedback in the viewport to highlight the issue.
- Create another material on the same cube and once again assign a color in the viewport display settings.
- Set both materials to Object Link in the material properties.
- Name the current scene "Scene 1" and proceed to create another scene named "Scene 2".
- Return to Scene 1, and using Alt+D instance the cube.
- Using Ctrl+ L, link the instance to Scene 2. Delete the newly created instance in Scene 1.
In Scene 2, assign the instance a different material than Scene 1 in edit mode. You now have 2 scenes, with 2 cubes that share mesh data, but that are using 2 different materials. This is the desired goal in practice.
Save the file and re-open it. Blender will have automatically assigned both cubes to 1 material.
Example.blend

Broken: 2.93.4 LTS; Broken: master **Short description of error** With two different objects in two different scenes sharing a same obdata Mesh, editing the mesh in one of the scene can fail to properly update object in the other scene. **Exact steps for others to reproduce the error** - Open attached file. - Go to scene 2. - Switch to Edit mode. - Assign the red material (first slot) to the cube in edit mode. - Switch back to Object mode. - Go to Scene 1, the Cube in Scene one still uses the second slot material (green). # Switch to edit mode and back, now the cube is shown with expected first material slot (red) as well. NOTE: If you replace step 4 by a mesh geometry editing (e.g. rotate the mesh in Edit mode), in current master there is the same missing update issue in Scene 1, but in 2.93LTS it is properly updated... Regression introduced by 51568030e9. [Example.blend](https://archive.blender.org/developer/F10831918/Example.blend) ------------------------ # Original report **System Information** Operating system: Windows-10-10.0.22000-SP0 64 Bits Graphics card: NVIDIA GeForce GTX 680/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 472.12 **Blender Version** Broken: version: 2.93.0, branch: master, commit date: 2021-06-02 11:21, hash: `84da05a8b8` **Short description of error** If you link an instanced object to another scene, having it's material link to object, it can have a different material from the non-instance. However upon saving and re-opening the scene, the instance's material will revert to that of the non-instance. **Exact steps for others to reproduce the error** - Open attached file or - Take the default cube and assign a material to it. In the viewport display settings assign a color for the material, this will give feedback in the viewport to highlight the issue. - Create another material on the same cube and once again assign a color in the viewport display settings. - Set both materials to Object Link in the material properties. - Name the current scene "Scene 1" and proceed to create another scene named "Scene 2". - Return to Scene 1, and using Alt+D instance the cube. - Using Ctrl+ L, link the instance to Scene 2. Delete the newly created instance in Scene 1. - In Scene 2, assign the instance a different material than Scene 1 in edit mode. You now have 2 scenes, with 2 cubes that share mesh data, but that are using 2 different materials. This is the desired goal in practice. - Save the file and re-open it. Blender will have automatically assigned both cubes to 1 material. [Example.blend](https://archive.blender.org/developer/F10831918/Example.blend)

daniellapalme@gmail.com commented

2021-10-07 05:35:33 +02:00

Added subscriber: @Bobo_The_Imp

Germano Cavalcante commented

2021-10-07 21:25:23 +02:00

Added subscriber: @mano-wii

Germano Cavalcante commented

2021-10-07 21:25:23 +02:00

Thanks for the report, I can confirm the problem.

I believe the #core module handles Read/Write .blend files (Am I right?), so tagging it.

Thanks for the report, I can confirm the problem. I believe the #core module handles Read/Write .blend files (Am I right?), so tagging it.

Bastien Montagne commented

2021-10-08 16:20:36 +02:00

Added subscriber: @mont29

Bastien Montagne commented

2021-10-08 16:20:36 +02:00

There is no write/load bug here, 'assigning a material in edit mode' means you assign the active material index (i.e. material slot) to the selected faces of the mesh. This will affect both objects, since they share the same mesh, assigning faces of that mesh to material slot 1 in one object will make it use material of material slot 1 in the other object as well.

The issue here is that object in scene 1 is not immediately updated (it is as soon as e.g. you switch to edit mode and back). Same goes if you edit mesh shape in Scene 2, go back to Object mode and switch to scene 1, you also need to force update to see the changes... Not sure what is happening here, it only happens in some specific order (e.g.if you change material slot assignment on mesh in scene 1, it is immediately updated in scene 2 as well).

There is no write/load bug here, 'assigning a material in edit mode' means you assign the active material index (i.e. material slot) to the selected faces of the *mesh*. This will affect both objects, since they share the same mesh, assigning faces of that mesh to material slot 1 in one object will make it use material of material slot 1 in the other object as well. The issue here is that object in scene 1 is not immediately updated (it is as soon as e.g. you switch to edit mode and back). Same goes if you edit mesh shape in Scene 2, go back to Object mode and switch to scene 1, you also need to force update to see the changes... Not sure what is happening here, it only happens in some specific order (e.g.if you change material slot assignment on mesh in scene 1, it is immediately updated in scene 2 as well).

Bastien Montagne changed title from ~~Linked Instances Across Scenes with Material Link Set to Object do not Retain Material Assignment Through Saves~~ to Linked Instances Across Scenes have unreliable updates when editing their common mesh data.

2021-10-08 16:34:52 +02:00

Germano Cavalcante commented

2021-10-08 17:16:48 +02:00

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

Germano Cavalcante commented

2021-10-08 17:16:48 +02:00

Oh I see!
The step "Set both materials to Object Link in the material properties" baffled my mind.
(I forgot to confirm)

Oh I see! The step "Set both materials to Object Link in the material properties" baffled my mind. (I forgot to confirm)

Bastien Montagne commented

2021-10-08 17:45:47 +02:00

Added subscriber: @ideasman42

Bastien Montagne commented

2021-10-08 17:45:47 +02:00

Mesh editing regression comes from 51568030e9 (tagging @ideasman42 here too).

Mesh editing regression comes from 51568030e9 (tagging @ideasman42 here too).

Philipp Oeser removed the

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Linked Instances Across Scenes have unreliable updates when editing their common mesh data. #91996

Switch to edit mode and back, now the cube is shown with expected first material slot (red) as well.

Original report