data copy is ommitting vgroups #90087

New Issue

Em Eckx · 2021-07-23T18:31:43+02:00

Em Eckx commented

2021-07-23 18:31:43 +02:00

System Information
Operating system: Windows 10
Graphics card: 3090 / 3060 / 1050ti

Blender Version
Broken: (Current Builds) (3.0.0 hash: fafd21b14c23, master, 2021-07-22)
Worked: (2.93.1 hash: d6b1d35bf874, master, 2021-07-12)
Caused by 3b6ee8cee7

Short description of error

Data copy is deleting vgroup data in 3.0 builds since the 12th.

Exact steps for others to reproduce the error

Running this script deletes the vertex group which began happening in 3.0 builds after the 12th.

import bpy

# all vertices belong to a single group

context = bpy.context
obj = context.object

#get evaluated object
obj_eval = obj.evaluated_get(context.evaluated_depsgraph_get())
print(obj_eval.vertex_groups[:]) #the evaluated object has groups

# and create new mesh from it
new_mesh = bpy.data.meshes.new_from_object(obj_eval)
print(new_mesh.vertices[0].groups[0].weight) # created mesh has groups and weight

# assign new mesh to the object
obj.data = new_mesh
print(obj.vertex_groups[:]) #vertex groups are gone

this example might be more linear

import bpy

context = bpy.context
obj = context.object
print(obj.vertex_groups[:])

# this piece used to preserve vertex groups but it doesn't
obj.data = bpy.data.meshes.new_from_object(obj)
print(obj.vertex_groups[:])

This is what happens in current 3.0 builds.
kfgTvLKgYu.mp4

This is what was happening in 2.93.1LTS and 3.0.0 on the 12th and prior.
GQZC9nXt9N.mp4

Vgroup data was also part of the copy which was expected behavior. The removal of the data is the issue attempting to be outlined.

**System Information** Operating system: Windows 10 Graphics card: 3090 / 3060 / 1050ti **Blender Version** Broken: (Current Builds) (3.0.0 hash: `fafd21b14c23`, master, 2021-07-22) Worked: (2.93.1 hash: `d6b1d35bf874`, master, 2021-07-12) Caused by 3b6ee8cee7 **Short description of error** Data copy is deleting vgroup data in 3.0 builds since the 12th. **Exact steps for others to reproduce the error** Running this script deletes the vertex group which began happening in 3.0 builds after the 12th. ``` import bpy # all vertices belong to a single group context = bpy.context obj = context.object #get evaluated object obj_eval = obj.evaluated_get(context.evaluated_depsgraph_get()) print(obj_eval.vertex_groups[:]) #the evaluated object has groups # and create new mesh from it new_mesh = bpy.data.meshes.new_from_object(obj_eval) print(new_mesh.vertices[0].groups[0].weight) # created mesh has groups and weight # assign new mesh to the object obj.data = new_mesh print(obj.vertex_groups[:]) #vertex groups are gone ``` this example might be more linear ``` import bpy context = bpy.context obj = context.object print(obj.vertex_groups[:]) # this piece used to preserve vertex groups but it doesn't obj.data = bpy.data.meshes.new_from_object(obj) print(obj.vertex_groups[:]) ``` This is what happens in current 3.0 builds. [kfgTvLKgYu.mp4](https://archive.blender.org/developer/F10235086/kfgTvLKgYu.mp4) This is what was happening in 2.93.1LTS and 3.0.0 on the 12th and prior. [GQZC9nXt9N.mp4](https://archive.blender.org/developer/F10235094/GQZC9nXt9N.mp4) Vgroup data was also part of the copy which was expected behavior. The removal of the data is the issue attempting to be outlined.

Em Eckx commented

2021-07-23 18:31:43 +02:00

Added subscriber: @masterxeon1001

Pratik Borhade commented

2021-07-24 03:45:34 +02:00

Added subscriber: @PratikPB2123

Pratik Borhade commented

2021-07-24 03:45:34 +02:00

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

Pratik Borhade commented

2021-07-24 03:45:34 +02:00

Can confirm. Possibly the culprit commit is 3b6ee8cee7 but will double check.

Can confirm. Possibly the culprit commit is 3b6ee8cee7 but will double check.

Hans Goudey commented

2021-07-24 03:46:49 +02:00

Added subscriber: @HooglyBoogly

Hans Goudey commented

2021-07-24 03:46:49 +02:00

It looks like this function implements mesh copying from scratch.
I don't have time to test right now, but a quick fix is probably adding these lines to BKE_mesh_nomain_to_mesh:

  BKE_defgroup_copy_list(&mesh_dst->vertex_group_names, &mesh_src->vertex_group_names);
  mesh_dst->vertex_group_active_index = mesh_src->vertex_group_active_index;

It looks like this function implements mesh copying from scratch. I don't have time to test right now, but a quick fix is probably adding these lines to `BKE_mesh_nomain_to_mesh`: ``` BKE_defgroup_copy_list(&mesh_dst->vertex_group_names, &mesh_src->vertex_group_names); mesh_dst->vertex_group_active_index = mesh_src->vertex_group_active_index; ```

Pratik Borhade commented

2021-07-24 06:49:30 +02:00

Caused by 3b6ee8cee7. Recent regression so marking this a high priority issue.

@HooglyBoogly , sorry did not check your message. Will let you know after testing the change.

Caused by 3b6ee8cee7. Recent regression so marking this a high priority issue. @HooglyBoogly , sorry did not check your message. Will let you know after testing the change.

Manuel Hofmann commented

2021-07-30 00:26:09 +02:00

Added subscriber: @ManuH