"Make Single User" does not unlink object from other scenes when creating Scene using "Linked Copy" #92978

New Issue

Samuel · 2021-11-10T02:11:25+01:00

Samuel commented

2021-11-10 02:11:25 +01:00

System Information
Operating system: Windows-10-10.0.19041-SP0 64 Bits
Graphics card: NVIDIA GeForce RTX 3070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 472.12

Blender Version
Broken: version: 2.93.6 Release Candidate, branch: master, commit date: 2021-11-04 08:11, hash: 1180b4ff4a
Worked: 2.90.1 (according to [description by user DAG here ]], who lists his software version in a [ https:*blender.stackexchange.com/questions/74460/how-to-unlink-remove-an-object-from-a-scene/227238#comment383264_74486 | comment higher in the same question, here .

Short description of error
Scenes created using the "Linked Copy" option do not allow objects to be unlinked via "Make Single User".
Additionally, in my testing, I have not found any way to make single user objects in a scene created using the "Linked Copy" option or in the original scene (i.e. creating a new object in either scene always creates a linked object). Objects deleted from one scene are also deleted in the other. Because of this, I have not been able to find a way to change a Scene created via "Linked Copy" independently of the original scene, making the "Linked Copy" option functionally useless.

Exact steps for others to reproduce the error

Open a new default file
Create a new scene using the "Linked Copy" option
Select the default cube in the new scene (will likely be already selected)
"Option" menu -> "Relations" -> "Make Single User"
Delete the cube in this Scene
Switch to the first Scene

Expected Result: The default cube is still in the first Scene
Observed Result: The default cube has been deleted from the first Scene

**System Information** Operating system: Windows-10-10.0.19041-SP0 64 Bits Graphics card: NVIDIA GeForce RTX 3070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 472.12 **Blender Version** Broken: version: 2.93.6 Release Candidate, branch: master, commit date: 2021-11-04 08:11, hash: `1180b4ff4a` Worked: 2.90.1 (according to [description by user DAG here ]], who lists his software version in a [[ https:*blender.stackexchange.com/questions/74460/how-to-unlink-remove-an-object-from-a-scene/227238#comment383264_74486 | comment higher in the same question, here ](https:*blender.stackexchange.com/questions/74460/how-to-unlink-remove-an-object-from-a-scene/227238#227238). **Short description of error** Scenes created using the "Linked Copy" option do not allow objects to be unlinked via "Make Single User". Additionally, in my testing, I have not found any way to make single user objects in a scene created using the "Linked Copy" option or in the original scene (i.e. creating a new object in either scene always creates a **linked** object). Objects deleted from one scene are also deleted in the other. Because of this, I have not been able to find a way to change a Scene created via "Linked Copy" independently of the original scene, making the "Linked Copy" option functionally useless. **Exact steps for others to reproduce the error** - Open a new default file - Create a new scene using the "Linked Copy" option - Select the default cube in the new scene (will likely be already selected) - "Option" menu -> "Relations" -> "Make Single User" - Delete the cube in this Scene - Switch to the first Scene Expected Result: The default cube is still in the first Scene Observed Result: The default cube has been deleted from the first Scene

Samuel commented

2021-11-10 02:11:25 +01:00

Added subscriber: @sunboy4224

blender-admin commented

2021-11-10 02:11:25 +01:00

#96720 was marked as duplicate of this issue

Philipp Oeser commented

2021-11-11 13:53:37 +01:00

Added subscribers: @mont29, @lichtwerk

Philipp Oeser commented

2021-11-11 13:53:37 +01:00

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

Philipp Oeser commented

2021-11-11 13:53:37 +01:00

In 2.79 this was working a bit more transparent out of the box.
2.79 linked the objects specifically [which could then be made single user "properly" - you get a new object in the linked scene, the original in the original scene].

Since 2.8, it is a bit more complicated:

a) objects in a collection wont be linked themselves, instead their collections are linked to a linked copy of a scene
- if you delete an object from that collection, it will be removed everywhere (because it is only the collection that is shared in multiple places)
- even if you make the object a single user in such a "shared-across-linked-scenes" collection [which indeed has an awkward behavior, but let me get to that later] it is still the same in this collection, deleting it deletes it everywhere
b) now if objects are directly in the master / Scene Collection, then they are not linked via a collection, it seems these are then linked as objects (as in 2.79)
- now Make Single User will act as expected (new object in the linked scene, the original in the original scene):
  T92978_b_scenario.blend

I would still say this is working more or less by design if you take the above in consideration (even though Make Single User objects for objects in linked scenes has lost its purpose tbh).
Plus, the behavior of Make Single User in the a) scenario is awkward (at least from the user perspective):

why are we even getting a copy of the object? (isnt the collection its only user?)
So I think we should not end up with Cube.001 at all in this case
T92978_a_scenario.blend

@mont29: opinions?

In 2.79 this was working a bit more transparent out of the box. 2.79 linked the objects specifically [which could then be made single user "properly" - you get a new object in the linked scene, the original in the original scene]. Since 2.8, it is a bit more complicated: - a) objects in a collection wont be linked themselves, instead their collections are linked to a linked copy of a scene - if you delete an object from that collection, it will be removed everywhere (because it is only the collection that is shared in multiple places) - even if you make the object a single user in such a "shared-across-linked-scenes" collection [which indeed has an awkward behavior, but let me get to that later] it is still the same in this collection, deleting it deletes it everywhere - b) now if objects are directly in the master / Scene Collection, then they are not linked via a collection, it seems these are then linked as objects (as in 2.79) - now `Make Single User` will act as expected (new object in the linked scene, the original in the original scene): [T92978_b_scenario.blend](https://archive.blender.org/developer/F11793691/T92978_b_scenario.blend) I would still say this is working more or less by design if you take the above in consideration (even though `Make Single User` objects for objects in linked scenes has lost its purpose tbh). Plus, the behavior of `Make Single User` in the a) scenario is awkward (at least from the user perspective): - why are we even getting a copy of the object? (isnt the collection its only user?) - So I think we should not end up with Cube.001 at all in this case [T92978_a_scenario.blend](https://archive.blender.org/developer/F11793692/T92978_a_scenario.blend) @mont29: opinions?

Germano Cavalcante commented

2021-11-11 14:34:28 +01:00

Added subscriber: @mano-wii

Germano Cavalcante commented

2021-11-11 14:34:28 +01:00

I tested it on blender 2.90.1 as mentioned, but the result is the same here.
From what I can see, what is linked is not the objects, but the collections. So any changes within a collection will change for all scenes with the same collection.

The description of Linked Copy itself says this:

Link in the collections from the current scene (shallow copy)

So a "solution" would be to make another collection for the new scene.

But the Linked Copy name is weird in my opinion. Makes the user think that the scene is linked. I think a more ideal name would be New with Linked Collections.

//This seems to be more of a support request than a bug in my opinion.
For support questions, we usually suggest trying community websites: https://www.blender.org/community/
But I realize that this has already been tried (without much success apparently).//

I tested it on blender 2.90.1 as mentioned, but the result is the same here. From what I can see, what is linked is not the objects, but the collections. So any changes within a collection will change for all scenes with the same collection. The description of `Linked Copy` itself says this: > Link in the **collections** from the current scene (shallow copy) So a "solution" would be to make another collection for the new scene. But the `Linked Copy` name is weird in my opinion. Makes the user think that the scene is linked. I think a more ideal name would be `New with Linked Collections`. --- //This seems to be more of a support request than a bug in my opinion. For support questions, we usually suggest trying community websites: https://www.blender.org/community/ But I realize that this has already been tried (without much success apparently).//

Samuel commented

2021-11-11 14:44:12 +01:00

Not to jump into a dev conversation, but rather than simply removing the Make Single User functionality for objects-in-linked-collections (as I believe @lichtwerk is suggesting), could you modify it to essentially perform the operation in scenario b) and place the new copy in the master/Scene Collection?

And/or, could you add functionality that lets me manipulate linked collections effectively:

When in a linked copy of a scene, right-clicking a linked collection, the options Instance to Scene and Unlink appear. I would expect Instance to Scene to make a copy of the Collection (and all objects therein) local to the current scene, and Unlink to simply remove/delete the Collection from the current scene while leaving it in others. However, Instance to Scene seems to do nothing (Edit: Rather it creates a copy of the Collection itself, without any child objects, though I'm not sure why), and Unlink seems to just delete the Collection across all Scenes.
Further, an option to link non-linked Collections to different scenes (as in scenario a), without having to perform a full "Linked Copy" of a Scene) would be useful, as I can't find that functionality for individual Collections anywhere.
As a user, Collections being linked (rather than objects) was not communicated clearly to me, I wasn't even aware that collections could be shared. A much bigger ask would be having some more communication when moving objects into/out of linked collections, and perhaps a "chain"/"link" icon next to a collection that is linked across multiple Scenes.

This is admittedly turning from a bug report more into a feature request, so I'm happy to repost elsewhere if you would prefer. Thank you for considering!

Not to jump into a dev conversation, but rather than simply removing the `Make Single User` functionality for objects-in-linked-collections (as I believe @lichtwerk is suggesting), could you modify it to essentially perform the operation in scenario b) and place the new copy in the master/Scene Collection? And/or, could you add functionality that lets me manipulate linked collections effectively: - When in a linked copy of a scene, right-clicking a linked collection, the options `Instance to Scene` and `Unlink` appear. I would expect `Instance to Scene` to make a copy of the Collection (and all objects therein) local to the current scene, and `Unlink` to simply remove/delete the Collection from the current scene while leaving it in others. However, `Instance to Scene` seems to do nothing (Edit: Rather it creates a copy of the Collection itself, without any child objects, though I'm not sure why), and `Unlink` seems to just delete the Collection across all Scenes. - Further, an option to link non-linked Collections to different scenes (as in scenario a), without having to perform a full "Linked Copy" of a Scene) would be useful, as I can't find that functionality for individual Collections anywhere. - As a user, Collections being linked (rather than objects) was not communicated clearly to me, I wasn't even aware that collections could be shared. A much bigger ask would be having some more communication when moving objects into/out of linked collections, and perhaps a "chain"/"link" icon next to a collection that is linked across multiple Scenes. This is admittedly turning from a bug report more into a feature request, so I'm happy to repost elsewhere if you would prefer. Thank you for considering!

Bastien Montagne commented

2021-11-15 17:47:57 +01:00

This is more a known issue I think... Indeed, code is mostly behaving as expected, user should make collection single user, since as already explained (unless linked to scene collection), the object has only one user, the collection linked in the viewlayer of both scenes.

The actual duplication of the object is indeed a 'bug', caused by the usage of BKE_object_scenes_users_get(bmain, ob) > 1 to check whether an object is used in more than one scene, which is no more valid as we saw above. Fixxing this is trivial, but does not really help on a practical point of view.

This rather need a proper re-design of how this tool is working.

This is more a known issue I think... Indeed, code is mostly behaving as expected, user should make collection single user, since as already explained (unless linked to scene collection), the object has only one user, the collection linked in the viewlayer of both scenes. The actual duplication of the object is indeed a 'bug', caused by the usage of `BKE_object_scenes_users_get(bmain, ob) > 1` to check whether an object is used in more than one scene, which is no more valid as we saw above. Fixxing this is trivial, but does not really help on a practical point of view. This rather need a proper re-design of how this tool is working.

Samuel commented

2021-11-15 23:05:43 +01:00

Are the uses of Right click on Collection -> Instance to Scene and Right click on Collection -> Unlink working as expected? In a Linked Copy scene, they seem like they're misbehaving. However, this could be covered in the proposed re-design.

Regardless, thank you all for investigating!

Are the uses of Right click on Collection -> `Instance to Scene` and Right click on Collection -> `Unlink` working as expected? In a `Linked Copy` scene, they seem like they're misbehaving. However, this could be covered in the proposed re-design. Regardless, thank you all for investigating!

Rombout Versluijs commented

2021-11-16 04:06:07 +01:00

Added subscriber: @RomboutVersluijs

Rombout Versluijs commented

2021-11-16 04:06:07 +01:00

What perhaps is confusing is that the collection does not have an indicator showing its a "multi-user" like copy-linked shows on say a cube. Its not visible clear whats is happening actually.
Only way we can see it, i guess, is context menu from a collection > unlink. That only indicates its a linked item. Should it show somewhere its a multi-user like it does with single objects?

There is however a flaw in this method. If use "Linked Copy", that the cube object and data dont show a multi user. But when i select the collection and use Object > Make Links > Objects Scene > Scene
Than i do get a multi-user on the data level but not on object level?! is that normal?

Attached simple cube. If you run that operator from object menu as i described, you do get a multi-user

Linked Copy.blend

EDIT
Never mind the scene, i still had the cube selected as well, thats why the make link worked like described. Though the collection should show its a link perhaps.

What perhaps is confusing is that the collection does not have an indicator showing its a "multi-user" like copy-linked shows on say a cube. Its not visible clear whats is happening actually. Only way we can see it, i guess, is context menu from a collection > unlink. That only indicates its a linked item. Should it show somewhere its a multi-user like it does with single objects? There is however a flaw in this method. If use "Linked Copy", that the cube object and data dont show a multi user. But when i select the collection and use Object > Make Links > Objects Scene > Scene Than i do get a multi-user on the data level but not on object level?! is that normal? Attached simple cube. If you run that operator from object menu as i described, you do get a multi-user [Linked Copy.blend](https://archive.blender.org/developer/F11812164/Linked_Copy.blend) EDIT Never mind the scene, i still had the cube selected as well, thats why the make link worked like described. Though the collection should show its a link perhaps.

Philipp Oeser commented

2021-11-17 22:13:33 +01:00

In #92978#1253885, @mont29 wrote:
... user should make collection single user

Sorry to ask, but how do you actually do this in this scenario?

If I look at the usecase from this report, what we probably want is single user copies of the collections of the source scene (having the same objects inside)
That way we can just unlink (not delete) anything that is in there and the source scene stays intact.
Not seeing a way to quickly do this though:

Duplicate Linked on a collection is the best bet here (will duplicate the objects while keeping the object data linked)
Make Single User on a collection in the Outliner is not implemented

In #92978#1252368, @sunboy4224 wrote:
Not to jump into a dev conversation, but rather than simply removing the Make Single User functionality for objects-in-linked-collections (as I believe @lichtwerk is suggesting), could you modify it to essentially perform the operation in scenario b) and place the new copy in the master/Scene Collection?

Possibly, but unsure if this is the best way (loosing the "organization" part of collections if they all end up in the scene collection)

When in a linked copy of a scene, right-clicking a linked collection, the options Instance to Scene and Unlink appear. I would expect Instance to Scene to make a copy of the Collection (and all objects therein) local to the current scene, and Unlink to simply remove/delete the Collection from the current scene while leaving it in others. However, Instance to Scene seems to do nothing (Edit: Rather it creates a copy of the Collection itself, without any child objects, though I'm not sure why), and Unlink seems to just delete the Collection across all Scenes.

Not sure I understand correctly:

Instance to Scene makes an instance https://docs.blender.org/manual/en/dev/scene_layout/object/properties/instancing/collection.html
Unlink will unlink from the parent collection (if the parent is shared across scenes, then it will be gone in all scenes, but if the parent is specific to that scene it will just be unlinked there)

Further, an option to link non-linked Collections to different scenes (as in scenario a), without having to perform a full "Linked Copy" of a Scene) would be useful, as I can't find that functionality for individual Collections anywhere.

Not sure if I understand correctly, but you can drag collections from a Blender File view Outliner to another View Layer view Outliner showing any scene you want

> In #92978#1253885, @mont29 wrote: > ... user should make collection single user Sorry to ask, but how do you actually do this in this scenario? If I look at the usecase from this report, what we probably want is single user copies of the collections of the source scene (having the same objects inside) That way we can just unlink (not delete) anything that is in there and the source scene stays intact. Not seeing a way to quickly do this though: - `Duplicate Linked` on a collection is the best bet here (will duplicate the objects while keeping the object data linked) - `Make Single User` on a collection in the Outliner is not implemented > In #92978#1252368, @sunboy4224 wrote: > Not to jump into a dev conversation, but rather than simply removing the `Make Single User` functionality for objects-in-linked-collections (as I believe @lichtwerk is suggesting), could you modify it to essentially perform the operation in scenario b) and place the new copy in the master/Scene Collection? Possibly, but unsure if this is the best way (loosing the "organization" part of collections if they all end up in the scene collection) > - When in a linked copy of a scene, right-clicking a linked collection, the options `Instance to Scene` and `Unlink` appear. I would expect `Instance to Scene` to make a copy of the Collection (and all objects therein) local to the current scene, and `Unlink` to simply remove/delete the Collection from the current scene while leaving it in others. However, `Instance to Scene` seems to do nothing (Edit: Rather it creates a copy of the Collection itself, without any child objects, though I'm not sure why), and `Unlink` seems to just delete the Collection across all Scenes. Not sure I understand correctly: - Instance to Scene makes an instance https://docs.blender.org/manual/en/dev/scene_layout/object/properties/instancing/collection.html - Unlink will unlink from the parent collection (if the parent is shared across scenes, then it will be gone in all scenes, but if the parent is specific to that scene it will just be unlinked there) > - Further, an option to link non-linked Collections to different scenes (as in scenario a), without having to perform a full "Linked Copy" of a Scene) would be useful, as I can't find that functionality for individual Collections anywhere. Not sure if I understand correctly, but you can drag collections from a `Blender File` view Outliner to another `View Layer` view Outliner showing any scene you want

Samuel commented

2021-11-18 01:33:18 +01:00

Possibly, but unsure if this is the best way (loosing the "organization" part of collections if they all end up in the scene collection)

You're right, the implementation you suggest above that line (single user copies of every collection in the scene, each of which contains linked duplicates of the objects) is the best/most intuitive implementation in my opinion. Perhaps there can be another option in the Scene copying menu (sibling to Linked Copy) that lets you link Collections as well, such as "New with Linked Collections" as suggested by @mano-wii, as the linked Collections feature may be valuable to some users.

Instance to Scene makes an instance

Ahh, I think I just misunderstood this feature. I thought it was the same as Make Single User, but for a Collection (a feature which I can't find, but that problem falls outside of the scope of a bug report/feature request).

Unlink will unlink from the parent collection

Maybe I was doing something wrong before (such as the parenting issue you mentioned), but this is now working as you describe. My mistake!

you can drag collections from a Blender File view Outliner to another View Layer view Outliner showing any scene you want

Good tip, thank you! A tad cumbersome IMHO, but good to know it's possible.

Ok, to recap, it looks like this "bug" is in fact a misunderstanding of the features surrounding scene copying and collection linking, as originally suggested by @lichtwerk. Thank you all for clearing this up! It looks like there are a couple of potential TODO's (re-thinking the workflow for Scene/Collection management as suggested by @mont29, adding a new Copy Scene option that duplicates a Collection hierarchy to a new Scene using single user Collections containing linked duplicate objects, adding the ability to make a collection single user [assuming this doesn't exist and not that I just can't find it]), but otherwise not really a singular "issue".

> Possibly, but unsure if this is the best way (loosing the "organization" part of collections if they all end up in the scene collection) You're right, the implementation you suggest above that line (single user copies of every collection in the scene, each of which contains linked duplicates of the objects) is the best/most intuitive implementation in my opinion. Perhaps there can be another option in the Scene copying menu (sibling to `Linked Copy`) that lets you link Collections as well, such as "`New with Linked Collections`" as suggested by @mano-wii, as the linked Collections feature may be valuable to some users. > Instance to Scene makes an instance Ahh, I think I just misunderstood this feature. I thought it was the same as `Make Single User`, but for a Collection (a feature which I can't find, but that problem falls outside of the scope of a bug report/feature request). > Unlink will unlink from the parent collection Maybe I was doing something wrong before (such as the parenting issue you mentioned), but this is now working as you describe. My mistake! > you can drag collections from a Blender File view Outliner to another View Layer view Outliner showing any scene you want Good tip, thank you! A tad cumbersome IMHO, but good to know it's possible. Ok, to recap, it looks like this "bug" is in fact a misunderstanding of the features surrounding scene copying and collection linking, as originally suggested by @lichtwerk. Thank you all for clearing this up! It looks like there are a couple of potential TODO's (re-thinking the workflow for Scene/Collection management as suggested by @mont29, adding a new Copy Scene option that duplicates a Collection hierarchy to a new Scene using single user Collections containing linked duplicate objects, adding the ability to make a collection single user [assuming this doesn't exist and not that I just can't find it]), but otherwise not really a singular "issue".

Bastien Montagne commented

2021-11-18 11:25:02 +01:00

In #92978#1255298, @lichtwerk wrote:

In #92978#1253885, @mont29 wrote:
... user should make collection single user

Sorry to ask, but how do you actually do this in this scenario?

Should have been right-click -> ID Data -> Make Single User in the outliner... Unfortunately this is only implemented for worlds and actions (!!!)... Tried checking if we could do this quickly at least for collections, but turns out this is not trivial, so guess this will adds to the TODO pile on this topic.

> In #92978#1255298, @lichtwerk wrote: >> In #92978#1253885, @mont29 wrote: >> ... user should make collection single user > > Sorry to ask, but how do you actually do this in this scenario? Should have been `right-click -> ID Data -> Make Single User` in the outliner... Unfortunately this is only implemented for worlds and actions (!!!)... Tried checking if we could do this quickly at least for collections, but turns out this is not trivial, so guess this will adds to the TODO pile on this topic.

Bastien Montagne commented

2022-03-23 09:22:20 +01:00

Added subscribers: @Colin_Knu, @PratikPB2123

Colin Knueppel commented

2022-03-29 18:55:35 +02:00

Please consider reworking system to be more like linking from external file and enable library override functionality. Then this linked copy option could inherit all the great work that's going into that other feature. And it will remove some confusion with two different systems using the term link but not working the same.

Philipp Oeser removed the

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"Make Single User" does not unlink object from other scenes when creating Scene using "Linked Copy" #92978