Content from linked scenes disappears after reopening the linked-to file #115486

New Issue

wojtaj · 2023-11-27T17:23:42+01:00

wojtaj commented

2023-11-27 17:23:42 +01:00

System Information
Operating system: Windows-10-10.0.22631-SP0 64 Bits
Graphics card: NVIDIA GeForce RTX 3070 Laptop GPU/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 546.17

Blender Version
Broken: version: 3.5.1, branch: blender-v3.5-release, commit date: 2023-04-24 18:11, hash: e1ccd9d4a1d3
Worked: 3.4

Short description of error
I noticed this issue while developing an addon to link multiple scenes into one blend file. The scenes seem to be linked properly at first, but when I save and reopen the linked-to blend, the contents from the other files are now missing. Linking collections only appears to work correctly.

Exact steps for others to reproduce the error

Create a new .blend file, save it as "one.blend"
Create a second new .blend file, save it as "two.blend"
Create a third new .blend file, save it as "target.blend"
Using File -> Link, link the default scenes from one.blend and two.blend to target.blend
Save, close, and reopen target.blend
one.blend and two.blend are still linked, but the contents are missing

6a) (alternative) one.blend stays properly linked if target.blend was saved while the scene from one.blend was active (interchangeable with two.blend)

**System Information** Operating system: Windows-10-10.0.22631-SP0 64 Bits Graphics card: NVIDIA GeForce RTX 3070 Laptop GPU/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 546.17 **Blender Version** Broken: version: 3.5.1, branch: blender-v3.5-release, commit date: 2023-04-24 18:11, hash: `e1ccd9d4a1d3` Worked: 3.4 **Short description of error** I noticed this issue while developing an addon to link multiple scenes into one blend file. The scenes seem to be linked properly at first, but when I save and reopen the linked-to blend, the contents from the other files are now missing. Linking collections only appears to work correctly. **Exact steps for others to reproduce the error** 1) Create a new .blend file, save it as "one.blend" 2) Create a second new .blend file, save it as "two.blend" 3) Create a third new .blend file, save it as "target.blend" 4) Using File -> Link, link the default scenes from one.blend and two.blend to target.blend [![Screenshot 2023-11-27 164843.png](/attachments/1e8fd61b-21e1-4988-b84d-56c4e2044e59)](url) 5) Save, close, and reopen target.blend 6) one.blend and two.blend are still linked, but the contents are missing [![Screenshot 2023-11-27 164943.png](/attachments/2833ad6f-99f3-455c-9403-459546389c5a)](url) 6a) (alternative) one.blend stays properly linked if target.blend was saved while the scene from one.blend was active (interchangeable with two.blend) [![Screenshot 2023-11-27 165119.png](/attachments/431701c5-0b60-446a-aaae-67683b66f3e0)](url)

Screenshot 2023-11-27 164843.png

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Screenshot 2023-11-27 164943.png

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Screenshot 2023-11-27 165119.png

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wojtaj added the

labels 2023-11-27 17:23:42 +01:00

Pratik Borhade commented

2023-12-06 11:43:19 +01:00

Hi, thanks for the report. I can confirm.
Guess this has been reported before but unable to locate, I'll bisect it anyways.

Hi, thanks for the report. I can confirm. Guess this has been reported before but unable to locate, I'll bisect it anyways.

Pratik Borhade added

and removed

labels 2023-12-06 11:43:38 +01:00

Pratik Borhade added

and removed

labels 2023-12-06 11:51:56 +01:00

Pratik Borhade commented

2023-12-07 06:13:01 +01:00

behavior changed between ae081b2de1d4 - 9cb061f4f011

behavior changed between `ae081b2de1d4 - 9cb061f4f011`

Pratik Borhade commented

2023-12-07 07:50:42 +01:00

Caused by 133dde41bb
But this is not a bug then as @mont29 said in #113109 (comment) because scene is unused

Caused by 133dde41bb5bbbbd083b12723f1ec9053764348a But this is not a bug then as @mont29 said in https://projects.blender.org/blender/blender/issues/113109#issuecomment-1036892 because scene is unused

Bastien Montagne commented

2023-12-07 12:05:04 +01:00

This is indeed the expected behavior currently, see also #106321 and #105786.

The Scene case is a bit more problematic than nodes or texts data-blocks, but I think ultimately the answer would be the same: if you want to keep an unused linked ID, you have to manually reference it in your local data somehow (typically by adding a Custom Property pointing to it, from Blender 4.0 onward).

(Technically, we could make an exception for linked Scene IDs, but then we end up again with the 'garbage data piling up in production files' issue, especially since Scenes would typically link in a lot of other things).

@brecht not sure if you'd have another point of view on this topic?

This is indeed the expected behavior currently, see also #106321 and #105786. The Scene case is a bit more problematic than nodes or texts data-blocks, but I think ultimately the answer would be the same: if you want to keep an unused linked ID, you have to manually reference it in your local data somehow (typically by adding a Custom Property pointing to it, from Blender 4.0 onward). (Technically, we _could_ make an exception for linked Scene IDs, but then we end up again with the 'garbage data piling up in production files' issue, especially since Scenes would typically link in a lot of other things). @brecht not sure if you'd have another point of view on this topic?

Brecht Van Lommel commented

2023-12-08 17:56:15 +01:00

@mont29 I think an exception for scenes would actually make sense. It's basically the top level datablock, there are cases where it doesn't really make sense to attach it to anything else. I think in some sense the main database is a user of the scene.

If we make an exception, would it be possible to have a distinction between directly and indirectly linked scenes? Like a background set scene would be indirectly link, and could be removed along with the scene using it. Or is that not practical in the design?

@mont29 I think an exception for scenes would actually make sense. It's basically the top level datablock, there are cases where it doesn't really make sense to attach it to anything else. I think in some sense the main database is a user of the scene. If we make an exception, would it be possible to have a distinction between directly and indirectly linked scenes? Like a background set scene would be indirectly link, and could be removed along with the scene using it. Or is that not practical in the design?

Bastien Montagne commented

2023-12-12 18:22:13 +01:00

@mont29 I think an exception for scenes would actually make sense. It's basically the top level datablock, there are cases where it doesn't really make sense to attach it to anything else. I think in some sense the main database is a user of the scene.

Make sense to me as well.

If we make an exception, would it be possible to have a distinction between directly and indirectly linked scenes? Like a background set scene would be indirectly link, and could be removed along with the scene using it. Or is that not practical in the design?

@brecht No, we do not have that info at all currently. We could add it (as a new flag in ID struct, that gets saved as part of the 'linked reference' ID on disk e.g., and is only set for scenes explicitly linked by the user from the FileBrowser)... That's more or less what was proposal nbr. 1 in #106321.

But I think it would be simpler to just never move a linked scene marked as 'directly linked' back to 'indirectly linked' status. That way, scenes that were indirectly linked (as a dependency of another linked data) and never e.g. made active in any window or workspace, or referenced by any other local ID, would still be discarded when their linked usage disappear.

Note that that would be going back to previous situation, for Scene IDs. I think that this is acceptable, considering that typically there are not hundreds or more of scenes in a blendfile, and that they are quite easily discoverable and browsable from the main UI.

> @mont29 I think an exception for scenes would actually make sense. It's basically the top level datablock, there are cases where it doesn't really make sense to attach it to anything else. I think in some sense the main database is a user of the scene. Make sense to me as well. > If we make an exception, would it be possible to have a distinction between directly and indirectly linked scenes? Like a background set scene would be indirectly link, and could be removed along with the scene using it. Or is that not practical in the design? @brecht No, we do not have that info at all currently. We could add it (as a new flag in ID struct, that gets saved as part of the 'linked reference' ID on disk e.g., and is only set for scenes explicitly linked by the user from the FileBrowser)... That's more or less what was proposal nbr. 1 in #106321. But I think it would be simpler to just never move a linked scene marked as 'directly linked' back to 'indirectly linked' status. That way, scenes that were indirectly linked (as a dependency of another linked data) and never e.g. made active in any window or workspace, or referenced by any other local ID, would still be discarded when their linked usage disappear. Note that that would be going back to previous situation, for Scene IDs. I think that this is acceptable, considering that typically there are not hundreds or more of scenes in a blendfile, and that they are quite easily discoverable and browsable from the main UI.

Brecht Van Lommel commented

2023-12-12 18:50:00 +01:00

But I think it would be simpler to just never move a linked scene marked as 'directly linked' back to 'indirectly linked' status. That way, scenes that were indirectly linked (as a dependency of another linked data) and never e.g. made active in any window or workspace, or referenced by any other local ID, would still be discarded when their linked usage disappear.

That sounds reasonable.

> But I think it would be simpler to just never move a linked scene marked as 'directly linked' back to 'indirectly linked' status. That way, scenes that were indirectly linked (as a dependency of another linked data) and never e.g. made active in any window or workspace, or referenced by any other local ID, would still be discarded when their linked usage disappear. That sounds reasonable.

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Bastien Montagne referenced this issue from a commit

2023-12-13 19:01:05 +01:00

Fix #115486: Linked scenes disappear after reopening file.

Bastien Montagne closed this issue

2023-12-13 19:01:06 +01:00

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