Translation operator moves Child-Of constrained bones in the parent space instead of world #42256

New Issue

Lukas Tönne · 2014-10-16T13:06:01+02:00

Lukas Tönne commented

2014-10-16 13:06:01 +02:00

Test file child_constraint_problem.blend

Select the top bone with the child-of constraint, press G to move it with the transform operator, observe the movement direction.

Bone with a child-of constraint to another bone. Moving the bone with the translation operator or the manipulators interprets the offset in the constraint target's ("parent") space instead of world space. Changing the world transform with a python script, however, works fine:

import bpy
from mathutils import *

ob = "Armature"
bone = "head"

def translate_world(obname, bonename, offset):
    scene = bpy.context.scene
    ob = scene.objects[obname]
    bone = ob.pose.bones[bonename]
    
    mat = Matrix.Translation(Vector(offset))
    bone.matrix = ob.matrix_world.inverted() * mat * bone.matrix

translate_world(ob, bone, (3,0,0))

Test file [child_constraint_problem.blend](https://archive.blender.org/developer/F117669/child_constraint_problem.blend) Select the top bone with the child-of constraint, press G to move it with the transform operator, observe the movement direction. Bone with a child-of constraint to another bone. Moving the bone with the translation operator or the manipulators interprets the offset in the constraint target's ("parent") space instead of world space. Changing the world transform with a python script, however, works fine: ``` import bpy from mathutils import * ob = "Armature" bone = "head" def translate_world(obname, bonename, offset): scene = bpy.context.scene ob = scene.objects[obname] bone = ob.pose.bones[bonename] mat = Matrix.Translation(Vector(offset)) bone.matrix = ob.matrix_world.inverted() * mat * bone.matrix translate_world(ob, bone, (3,0,0)) ```

Lukas Tönne commented

2014-10-16 13:06:01 +02:00

Changed status to: 'Open'

Bastien Montagne was assigned by Lukas Tönne

2014-10-16 13:06:01 +02:00

Lukas Tönne commented

2014-10-16 13:06:01 +02:00

Added subscriber: @LukasTonne

Lukas Tönne commented

2014-10-16 13:35:25 +02:00

The problem seems to be related to translation offset, disabling these 3 lines fixes the directions (but breaks gives wrong translation from rotational part):
https://developer.blender.org/diffusion/B/browse/master/source/blender/blenkernel/intern/constraint.c$814

Disabling inverse matrix for transform operator also seems to "fix" the effect:
https://developer.blender.org/diffusion/B/browse/master/source/blender/editors/transform/transform_conversions.c$4774

The problem seems to be related to translation offset, disabling these 3 lines fixes the directions (but breaks gives wrong translation from rotational part): https://developer.blender.org/diffusion/B/browse/master/source/blender/blenkernel/intern/constraint.c$814 Disabling inverse matrix for transform operator also seems to "fix" the effect: https://developer.blender.org/diffusion/B/browse/master/source/blender/editors/transform/transform_conversions.c$4774

Bastien Montagne commented

2014-10-16 14:55:40 +02:00

So, could reproduce the same issue with mere objects - as soon as you do not use all parent's transform, and do rotate the parent, transform is broken.

child_constraint_noloc_transform_issue.blend

This has clearly to see with constinv and the hack done at the end of childof_evaluate() (first link by Lukas in above comment). Still digging…

So, could reproduce the same issue with mere objects - as soon as you do not use all parent's transform, and do rotate the parent, transform is broken. [child_constraint_noloc_transform_issue.blend](https://archive.blender.org/developer/F117687/child_constraint_noloc_transform_issue.blend) This has clearly to see with constinv and the hack done at the end of `childof_evaluate()` (first link by Lukas in above comment). Still digging…

Joshua Leung commented

2014-10-16 15:27:33 +02:00

Added subscriber: @JoshuaLeung