Page MenuHome
Create Task
Maniphest T48944

Copy Rotation bone constraint on non-positively scaled armature
Closed, ArchivedPublic
Actions

Description

System Information
Linux Mint 17.2
Intel Integrated Graphics Controller

Blender Version
Broken: 2.77a abf6f08
Worked: 2.76b f337fea

Short description of error
When a bone has a Copy Rotation constraint in Local Space with Influence ≠ 1.0, and the armature object has a negative scale, the rotation is incoherent.

Exact steps for others to reproduce the error

  • Create Armature Object
  • Create two bones
  • Create Copy Rotation constraint from one bone to the other
  • Set the constraint Space to Local, the Influence to eg. 0.5
  • In Object Mode, set the armature object's scale to a negative value in any axis

bug_copy_rotation.blend379 KBDownload

Related Objects

Event Timeline

Damien Picard (pioverfour) created this task.Jul 25 2016, 4:58 PM
Sergey Sharybin (sergey) changed the task status from Unknown Status to Unknown Status.Jul 26 2016, 2:05 PM
Sergey Sharybin (sergey) claimed this task.
Sergey Sharybin (sergey) added a subscriber: Sergey Sharybin (sergey).

This is a degenerative case where negative scale can not be distinguished from rotation from the transformation matrix (which is currently used by the constraints stack).

This is a known limitation which can't be really solved in the current design and it is a subject for the improvements in 2.8.

So thanks for the report, but closing it.

Karja Krähwald (karja) added a subscriber: Karja Krähwald (karja).May 26 2019, 11:15 AM

@Sergey Sharybin (sergey)
Is this still something that is get looked into for 2.8?
This issue keeps coming back to me mainly because its very comfortable to work with mirrored armature parts. Separate hand armatures for example can be reused and more easily updated this way:

Mirrored arm.blend772 KBDownload

Any hopes?

Sergey Sharybin (sergey) added a comment.May 26 2019, 2:33 PM

This is related on fundamentals of constraint stack design. This is something where node based setups will help solving mathematical ambiguity and give more artistic control, but there is no design for this yet.