Object join doesn't respect parenting #76556

New Issue

Ricardo de Sena · 2020-05-08T17:01:36+02:00

Ricardo de Sena commented

2020-05-08 17:01:36 +02:00

System Information
Operating system: Windows 10
Graphics card: NVidia GeForce Gt730

Blender Version
Blender 2.82A and Blender 2.83Beta 2020/05/08

Short description of error
When selecting two objects and doing the command Ctrl + Join they disappear.

Exact steps for others to reproduce the error

The error occurs when selecting the smallest and then the largest object and pressing {key Ctrl J}
But when selecting the big one and then the small one the error doesn't happen.
ErrorCtrl+Join.blend

**System Information** Operating system: Windows 10 Graphics card: NVidia GeForce Gt730 **Blender Version** Blender 2.82A and Blender 2.83Beta 2020/05/08 **Short description of error** When selecting two objects and doing the command Ctrl + Join they disappear. **Exact steps for others to reproduce the error** The error occurs when selecting the smallest and then the largest object and pressing {key Ctrl J} But when selecting the big one and then the small one the error doesn't happen. [ErrorCtrl+Join.blend](https://archive.blender.org/developer/F8520918/ErrorCtrl_Join.blend)

Ricardo de Sena commented

2020-05-08 17:01:36 +02:00

Added subscriber: @rsenas

Ankit Meel changed title from ~~Crash on Ctrl+Join two objects in mode object.~~ to Objects disappear on Ctrl+Join based on order of selection

2020-05-08 18:28:38 +02:00

Ankit Meel commented

2020-05-08 18:28:38 +02:00

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

Ankit Meel commented

2020-05-08 18:28:38 +02:00

Added subscriber: @ankitm

Alaska commented

2020-05-09 00:07:24 +02:00

Added subscriber: @Alaska

Alaska commented

2020-05-09 00:07:24 +02:00

@ankitm I don't believe this is a bug. The small object is being joined to a large object. The large object is the child of the small object and has a different position to the parent.
The objects doesn't disappear, they just shift to the location of the child object which is now "reset" because it no longer has a parent to reference it's location off of.

If you unparent the objects then join them, the issue does not occur.

@ankitm I don't believe this is a bug. The small object is being joined to a large object. The large object is the child of the small object and has a different position to the parent. The objects doesn't disappear, they just shift to the location of the child object which is now "reset" because it no longer has a parent to reference it's location off of. If you unparent the objects then join them, the issue does not occur.

Ankit Meel commented

2020-05-09 08:11:17 +02:00

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

Ankit Meel commented

2020-05-09 09:36:42 +02:00

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

Ankit Meel closed this issue

2020-05-09 09:36:42 +02:00

Ankit Meel self-assigned this 2020-05-09 09:36:42 +02:00

Ankit Meel commented

2020-05-09 09:36:42 +02:00

Right, I didn't check in outliner.

Brecht Van Lommel commented

2020-05-09 16:41:14 +02:00

Added subscriber: @brecht

Brecht Van Lommel commented

2020-05-09 16:41:14 +02:00

Changed status from 'Archived' to: 'Confirmed'

Brecht Van Lommel reopened this issue

2020-05-09 16:41:14 +02:00

Ankit Meel was unassigned by Brecht Van Lommel

2020-05-09 16:41:14 +02:00

Brecht Van Lommel commented

2020-05-09 16:41:14 +02:00

The object transform including parenting should be applied to the vertex coordinates, so that the joined vertices remain in the same location.

Ricardo de Sena commented

2020-05-11 18:25:00 +02:00

Always learning and being more attentive. Thank you.

Hans Goudey commented

2020-05-12 21:30:57 +02:00

Added subscriber: @HooglyBoogly

Hans Goudey self-assigned this 2020-05-12 21:30:57 +02:00

Hans Goudey commented

2020-05-12 21:30:57 +02:00

Here's a simpler demonstration. The problem is a bit different with different object types.
simplescreenrecorder-2020-05-12_15.45.28.mp4

Mesh: Parent and child use the child transform without parenting.
Curve: Same
Gpencil: Parent stays in the same location, child uses its own transform.
Armature: Dependency cycle. This probably doesn't apply here.
Join Parented Objects Test.blend

Here's a simpler demonstration. The problem is a bit different with different object types. [simplescreenrecorder-2020-05-12_15.45.28.mp4](https://archive.blender.org/developer/F8531367/simplescreenrecorder-2020-05-12_15.45.28.mp4) - **Mesh**: Parent and child use the child transform without parenting. - **Curve**: Same - **Gpencil**: Parent stays in the same location, child uses its own transform. - **Armature**: Dependency cycle. This probably doesn't apply here. [Join Parented Objects Test.blend](https://archive.blender.org/developer/F8531357/Join_Parented_Objects_Test.blend)

Hans Goudey changed title from ~~Objects disappear on Ctrl+Join based on order of selection~~ to Object join doesn't respect parent transform of child object

2020-05-12 21:37:46 +02:00

Hans Goudey changed title from ~~Object join doesn't respect parent transform of child object~~ to Object join doesn't respect parenting

2020-05-12 21:38:46 +02:00

sok0 commented

2020-05-13 16:22:19 +02:00

Added subscriber: @sok0

sok0 commented

2020-05-13 16:22:19 +02:00

Isn't this behavior to be expected due to the parent inverse matrix? The parent object has moved since it was parented to the child object (verified below) . As a result the child object moves back to its basis transform location when the parenting relationship is broken.

To avoid this quirk of the parent inverse matrix, there are two options:

Apply all transforms to the parent with Ctrl+A. This will also reset the parent inverse matrix of child objects
Clear Parent and Keep Transformation on the child with Alt+P.
Either way, you then can join objects with the desired result, no need to change to the join operator.

footnote:

# move parent back to it's original location at time of parenting
bpy.data.objects['Slice.006'].matrix_basis = bpy.data.objects['Slice.004'].matrix_parent_inverse.inverted()
#undo the parenting operation
bpy.data.objects['Slice.004'].parent = None

Isn't this behavior to be expected due to the parent inverse matrix? The parent object has moved since it was parented to the child object (verified below) . As a result the child object moves back to its basis transform location when the parenting relationship is broken. To avoid this quirk of the parent inverse matrix, there are two options: 1. Apply all transforms to the parent with Ctrl+A. This will also reset the parent inverse matrix of child objects 2. Clear Parent and Keep Transformation on the child with Alt+P. Either way, you then can join objects with the desired result, no need to change to the join operator. footnote: ``` # move parent back to it's original location at time of parenting bpy.data.objects['Slice.006'].matrix_basis = bpy.data.objects['Slice.004'].matrix_parent_inverse.inverted() #undo the parenting operation bpy.data.objects['Slice.004'].parent = None ```

blender-admin commented

2020-05-13 21:21:30 +02:00

This issue was referenced by 5e96c43854

This issue was referenced by 5e96c438546932ca875aa35afb8c73f9a68d62a1

Hans Goudey commented

2020-05-13 21:22:00 +02:00

Changed status from 'Confirmed' to: 'Resolved'

Hans Goudey closed this issue

2020-05-13 21:22:00 +02:00

Hans Goudey commented

2020-05-13 21:28:35 +02:00

In #76556#930761, @sok0 wrote:
Either way, you then can join objects with the desired result, no need to change to the join operator.

The change is simple anyway, and avoids the need for applying the parent transform first.

> In #76556#930761, @sok0 wrote: > Either way, you then can join objects with the desired result, no need to change to the join operator. The change is simple anyway, and avoids the need for applying the parent transform first.

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Object join doesn't respect parenting #76556