weird movement of Bone in child of constraint #56975

New Issue

pratik solanki · 2018-09-29T14:57:18+02:00

pratik solanki commented

2018-09-29 14:57:18 +02:00

System Information
ubuntu 16.4

Blender Version
blender 2.8 alpha2 0f9b7560db

Short description of error
Bone movement are not in local space after adding childof constraint

Exact steps for others to reproduce the error

add armature and add 2 bones A and B
add child off constraint in A and select target as bone B
press clear inverse ,and set inverse

now move bone A in any direction it might move as expected , but rotate B in any random direction , and then try moving Bone A ,

Bone A will not move in local space ,

check the blendfile ,
go to frame1 and move bone A , it will move normal ,
got to frame 20 and move Bone A, it will not move as expected
test childoff bone.blend

**System Information** ubuntu 16.4 **Blender Version** blender 2.8 alpha2 0f9b7560db3 **Short description of error** Bone movement are not in local space after adding childof constraint **Exact steps for others to reproduce the error** add armature and add 2 bones A and B add child off constraint in A and select target as bone B press clear inverse ,and set inverse now move bone A in any direction it might move as expected , but rotate B in any random direction , and then try moving Bone A , Bone A will not move in local space , check the blendfile , go to frame1 and move bone A , it will move normal , got to frame 20 and move Bone A, it will not move as expected [test childoff bone.blend](https://archive.blender.org/developer/F4862786/test_childoff_bone.blend)

pratik solanki commented

2018-09-29 14:57:18 +02:00

Added subscriber: @pratiksolanki

Bastien Montagne commented

2018-09-30 21:52:34 +02:00

Added subscriber: @mont29

Bastien Montagne commented

2018-09-30 21:52:34 +02:00

Did you check whether you have same behavior (issue) with 2.79? Can you please attach a 2.79 .blend file with same setup (for comparison)?

pratik solanki commented

2018-10-01 05:28:59 +02:00

here is a 2.79 file ,, it works great in 2.79
test childoff bone 2.79.blend

here is a 2.79 file ,, it works great in 2.79 [test childoff bone 2.79.blend](https://archive.blender.org/developer/F4885875/test_childoff_bone_2.79.blend)

Campbell Barton was assigned by Bastien Montagne

2018-10-01 08:14:59 +02:00

Bastien Montagne commented

2018-10-01 08:14:59 +02:00

Added subscriber: @ideasman42

Bastien Montagne commented

2018-10-01 08:14:59 +02:00

OK thanks, can confirm the issue, Grabbing the child bone indeed gives crazy directions once parent one is rotated, in 2.8.

@ideasman42 there is probably something that went wrong at some point in transform code?

OK thanks, can confirm the issue, Grabbing the child bone indeed gives crazy directions once parent one is rotated, in 2.8. @ideasman42 there is probably something that went wrong at some point in transform code?

Alexander Gavrilov commented

2018-10-01 12:53:25 +02:00

Added subscriber: @angavrilov

Alexander Gavrilov commented

2018-10-01 12:53:25 +02:00

To clarify, this is obviously a problem in the transform operators, not the constraints: if you directly change the properties, it works completely as expected.

Basically, Child Of (and any similar constraint) works like real parenting in that it effectively changes the local space coordinate system of the child by left-multiplying a matrix, so the transform operators need to consider that.

To clarify, this is obviously a problem in the transform operators, not the constraints: if you directly change the properties, it works completely as expected. Basically, Child Of (and any similar constraint) works like real parenting in that it effectively changes the local space coordinate system of the child by left-multiplying a matrix, so the transform operators need to consider that.

Campbell Barton commented

2018-10-03 03:57:39 +02:00

Caused by 126e6c8e1d, looking further into it.

Caused by 126e6c8e1d, looking further into it.

blender-admin commented

2018-10-03 04:21:46 +02:00

This issue was referenced by fb8d268f62

This issue was referenced by fb8d268f6212dfc1a27f048eed25e0ae5622d34b

Campbell Barton commented

2018-10-03 04:24:50 +02:00

Changed status from 'Open' to: 'Resolved'

Campbell Barton closed this issue

2018-10-03 04:24:50 +02:00

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weird movement of Bone in child of constraint #56975