Linked Mesh Editing Doesn't Work As Expected When Using Data Transfer Modifier #73895

New Issue

Kamil Makowski · 2020-02-16T22:16:11+01:00

Kamil Makowski commented

2020-02-16 22:16:11 +01:00

System Information
Operating system: Windows-10-10.0.17763-SP0 64 Bits
Graphics card: GeForce GTX 970/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 442.19

Blender Version
Broken: version: 2.82 (sub 7), branch: master, commit date: 2020-02-12 16:20, hash: 77d23b0bd7
Worked: 2.81 (sub 16), branch: master, commit date: 2019-12-04 11:32, hash: f1aa4d18d4

Short description of error
Object instances doesn't work as in blender 2.81

Exact steps for others to reproduce the error

In blender 2.81, after entering the edit mode, all instances become active. You can see changes in real time.
Screen below:

In Blender 2.82 it work ok till some time. I couldn't determine at what moment it breaks...

Changes appears only after You enter to object mode.

Here is blend file to test
instances_issue.blend

**System Information** Operating system: Windows-10-10.0.17763-SP0 64 Bits Graphics card: GeForce GTX 970/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 442.19 **Blender Version** Broken: version: 2.82 (sub 7), branch: master, commit date: 2020-02-12 16:20, hash: `77d23b0bd7` Worked: 2.81 (sub 16), branch: master, commit date: 2019-12-04 11:32, hash: `f1aa4d18d4` **Short description of error** Object instances doesn't work as in blender 2.81 **Exact steps for others to reproduce the error** In blender 2.81, after entering the edit mode, all instances become active. You can see changes in real time. Screen below: ![image.png](https://archive.blender.org/developer/F8343700/image.png) In Blender 2.82 it work ok till some time. I couldn't determine at what moment it breaks... ![image.png](https://archive.blender.org/developer/F8343702/image.png) Changes appears only after You enter to object mode. ![image.png](https://archive.blender.org/developer/F8343730/image.png) Here is blend file to test [instances_issue.blend](https://archive.blender.org/developer/F8343708/instances_issue.blend)

Kamil Makowski commented

2020-02-16 22:16:11 +01:00

Added subscriber: @kamilozo

Campbell Barton commented

2020-02-17 03:30:42 +01:00

Added subscriber: @ideasman42

Campbell Barton commented

2020-02-17 03:30:42 +01:00

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

Jeroen Bakker was assigned by Campbell Barton

2020-02-17 03:30:42 +01:00

Campbell Barton commented

2020-02-17 03:30:42 +01:00

Confirmed, the strange thing about this behavior, is making a linked duplicate of Veg_Tree_Birch_A.002 does show in edit mode when any of the other objects are edited.

Confirmed, the strange thing about this behavior, is making a linked duplicate of `Veg_Tree_Birch_A.002` does show in edit mode when any of the other objects are edited.

Kamil Makowski commented

2020-03-10 09:56:02 +01:00

Hi. Its any chance to fix this issue and ad it to upcoming Blender 2.82a proposed revisions? For everyone who works in game industry this is a very annoying issue.

Jeroen Bakker commented

2020-03-10 10:16:27 +01:00

B282a is for crucial issues only (crashes, high prio etc). This might be an annoying issue for a small group of people, but if we let every annoyance become high prio than we will never be able to release anything. Better to keep to the proposed release schedule.

It is on my desk for b283.

B282a is for crucial issues only (crashes, high prio etc). This might be an annoying issue for a small group of people, but if we let every annoyance become high prio than we will never be able to release anything. Better to keep to the proposed release schedule. It is on my desk for b283.

Jeroen Bakker commented

2020-03-30 16:03:49 +02:00

After minimizing the scene it is clear that this related to the data transfer modifiers that are used. After removing the data transfer modifier it seems to work. Note that disabling the modifier isn't enough.

See here for the minimum example.

#73895.blend

I will check if we can finetune this.

DRW_object_is_in_edit_mode ask the dependency graph if the object is changed. the depsgraph response that it is changed so the drawing assumes that it is a different mesh.

This is correct as the data transfer modifier adds data to the source mesh so the mesh is modified in the provided file. In the given example files both meshes are different. Only when selecting the original tree and enter edit mode result in that both meshes are in edit mode. The fact for this is that you always edit the base mesh.

In blender 2.82 we introduced the option to make edit mode modifier aware to overcome several issues.

editing objects in multiple windows at once.
don't show modifiers from other objects when editing a different object with the same base mesh

A solution to this specific problem is to not change the source mesh when the modifier is disabled in editmode or cage mode. Currently the object is already modified during building of the depsgraph. Which is really early on and might be a limitation of the current design. I will need to check with others as this is a bit outside of my knowledge.

After minimizing the scene it is clear that this related to the data transfer modifiers that are used. After removing the data transfer modifier it seems to work. Note that disabling the modifier isn't enough. See here for the minimum example. [#73895.blend](https://archive.blender.org/developer/F8436955/T73895.blend) I will check if we can finetune this. `DRW_object_is_in_edit_mode` ask the dependency graph if the object is changed. the depsgraph response that it is changed so the drawing assumes that it is a different mesh. This is correct as the data transfer modifier adds data to the source mesh so the mesh is modified in the provided file. In the given example files both meshes are different. Only when selecting the original tree and enter edit mode result in that both meshes are in edit mode. The fact for this is that you always edit the base mesh. In blender 2.82 we introduced the option to make edit mode modifier aware to overcome several issues. * editing objects in multiple windows at once. * don't show modifiers from other objects when editing a different object with the same base mesh A solution to this specific problem is to not change the source mesh when the modifier is disabled in editmode or cage mode. Currently the object is already modified during building of the depsgraph. Which is really early on and might be a limitation of the current design. I will need to check with others as this is a bit outside of my knowledge.

Jeroen Bakker commented

2020-03-31 09:03:52 +02:00

The data transfer node changes the source object by adding some custom data masks
(MOD_datatransfer.c#130 -> DEG_add_customdata_mask(ctx->node, dtmd->ob_source, &cddata_masks);.
This makes the object modified as it will generates and store the custom data layers in the source object. This data will then be used during the transfer.

Removing the mentioned line will let the user edit both meshes, but of course would break the data transfer.
Blender 2.82 is more strict in the linked mesh edit, as the previous implementation could crash or render undesired results.

I will set this issue to known issue for now. as my impression the solution would need a redesign of the data transfer modifier. The linked mesh edit works as designed.

Related reports:

#72733 (Issue with shared meshes overwriting modifiers)
#73095 ([Edit Mesh] overlay of linked meshes in Edit Mode. [2.82 regression])

The data transfer node changes the source object by adding some custom data masks (`MOD_datatransfer.c#130` -> `DEG_add_customdata_mask(ctx->node, dtmd->ob_source, &cddata_masks);`. This makes the object modified as it will generates and store the custom data layers in the source object. This data will then be used during the transfer. Removing the mentioned line will let the user edit both meshes, but of course would break the data transfer. Blender 2.82 is more strict in the linked mesh edit, as the previous implementation could crash or render undesired results. I will set this issue to known issue for now. as my impression the solution would need a redesign of the data transfer modifier. The linked mesh edit works as designed. Related reports: * #72733 (Issue with shared meshes overwriting modifiers) * #73095 ([Edit Mesh] overlay of linked meshes in Edit Mode. [2.82 regression])

Jeroen Bakker changed title from ~~Object instances doesn't work properly~~ to Linked Mesh Editing Doesn't Work As Expected When Using Data Transfer Modifier

2020-03-31 09:05:06 +02:00

Jeroen Bakker removed their assignment 2020-03-31 09:15:08 +02:00

Jeroen Bakker commented

2020-03-31 09:15:08 +02:00

Added subscriber: @Jeroen-Bakker

Kamil Makowski commented

2020-03-31 22:42:52 +02:00

Ok , I understand. So for solution we must wait a little longer than expected or its a higher possibility to have this situation work in blender 2.83?

Gilberto Rodrigues commented

2020-05-10 08:44:37 +02:00

Added subscriber: @Gilberto.R

Gilberto Rodrigues commented

2020-05-10 08:44:37 +02:00

@kamilozo Unfortunately not for 2.83.0. It's tagged as a Known Issue, so it won't be worked on for a while as this requires a lot of work and the developers are busy with other priorities.

Philipp Oeser removed the

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Linked Mesh Editing Doesn't Work As Expected When Using Data Transfer Modifier #73895