Copy Location of Bones seems to lag and leads to animation errors #25624

New Issue

Luca C. · 2011-01-13T20:48:58+01:00

Luca C. commented

2011-01-13 20:48:58 +01:00

%%%Hey there everyone,

I found this bug while trying to realize an IK/FK switch with only one controller ...
It works but the animation is kind of laging see my walkcycle vid for to see what i mean:
http://www.youtube.com/watch?v=fiJSJD_By6A
Or rotate the Bone "Parent" in my blend file quickly.

To explane my rigging:
I have got the "Parent" Bone and his child named "FK" wich copies the rotation of the "Controller".
And I got the Bone "IK" wich finally will deform the mesh and copies the location and rotation from the Bone "Controller".
The "Controller" is the one you should use for your IK things and it copies the location of "FK" (to get FK mode to work).

I didn't add the IK/FK switch or the IK constraint to keep it as simple as possible so you wont be able to switch between IK and FK.

If I switch to IK (in a blend file WITH the switch) the problem doesn't appear.
If I switch to FK and move or rotate the Bone "Parten" quickly the other bones follows with a delay.
This also happens when you are animating as you can see in the vid.

AND if you rotate or move the "Parent" and then abort it by pressing the right mouse button the bones won't follow the "Parent" back to its first position.

I hope this is not a logical mistake of me but I've checked it several times and it SHOULD work so i guess it's a bug in blender.

To my System:

Windows 7 Professionel 64x (German)
Nvidia GeForce 460 (Gainward, 1024MB, up to DirectX11)
Intel Core Two Duo E6550 @ 2.33GHz
2GB DDR2 RAM

Blender 2.56 x32 r34300 (also tested with the official 2.56 x64 version)
Python 2.7.1 (not shure sry i think it's the 64x not 32x)

I hope you can fix it easily and i hope i didn't blow up your minds with my confusing rigging ;)%%%

%%%Hey there everyone, I found this bug while trying to realize an IK/FK switch with only one controller ... It works but the animation is kind of laging see my walkcycle vid for to see what i mean: http://www.youtube.com/watch?v=fiJSJD_By6A Or rotate the Bone "Parent" in my blend file quickly. To explane my rigging: I have got the "Parent" Bone and his child named "FK" wich copies the rotation of the "Controller". And I got the Bone "IK" wich finally will deform the mesh and copies the location and rotation from the Bone "Controller". The "Controller" is the one you should use for your IK things and it copies the location of "FK" (to get FK mode to work). I didn't add the IK/FK switch or the IK constraint to keep it as simple as possible so you wont be able to switch between IK and FK. If I switch to IK (in a blend file WITH the switch) the problem doesn't appear. If I switch to FK and move or rotate the Bone "Parten" quickly the other bones follows with a delay. This also happens when you are animating as you can see in the vid. AND if you rotate or move the "Parent" and then abort it by pressing the right mouse button the bones won't follow the "Parent" back to its first position. I hope this is not a logical mistake of me but I've checked it several times and it SHOULD work so i guess it's a bug in blender. To my System: Windows 7 Professionel 64x (German) Nvidia GeForce 460 (Gainward, 1024MB, up to DirectX11) Intel Core Two Duo E6550 @ 2.33GHz 2GB DDR2 RAM Blender 2.56 x32 r34300 (also tested with the official 2.56 x64 version) Python 2.7.1 (not shure sry i think it's the 64x not 32x) I hope you can fix it easily and i hope i didn't blow up your minds with my confusing rigging ;)%%%

Luca C. commented

2011-01-13 20:48:58 +01:00

Changed status to: 'Open'

Joshua Leung commented

2011-01-14 00:32:16 +01:00

%%%You've got a classic case of "cyclic dependencies". Tabbing in/out of Editmode will reveal this, as well as any "lagging" issues you may notice especially after cancelling transforms, but also in other cases.

This is a very well known limitation of Blender's current depsgraph+evaluation implementation, which can only "see" entire objects and/or bones instead of by components only. In effect, Blender only "sees":
Parent -> FK
Controller -> IK
Controller -> FK ()
FK -> Controller ()

(*) this is the cyclic dependency: Controller <-> FK
Blender cannot determine which entity should be fully evaluated first, so it takes its pick and one of them usually loses out, leading to lagging.

For these IK/FK switching setups, it'd be better in the long run for you to use the standard "3-rig" setup:

IK Chains - user editable
FK Chains - user editable
Deform bones copying the transforms of IK/FK chains - users shouldn't edit this%%%

%%%You've got a classic case of "cyclic dependencies". Tabbing in/out of Editmode will reveal this, as well as any "lagging" issues you may notice especially after cancelling transforms, but also in other cases. This is a very well known limitation of Blender's current depsgraph+evaluation implementation, which can only "see" entire objects and/or bones instead of by components only. In effect, Blender only "sees": Parent -> FK Controller -> IK Controller -> FK (*) FK -> Controller (*) (*) this is the cyclic dependency: Controller <-> FK Blender cannot determine which entity should be fully evaluated first, so it takes its pick and one of them usually loses out, leading to lagging. For these IK/FK switching setups, it'd be better in the long run for you to use the standard "3-rig" setup: 1) IK Chains - user editable 2) FK Chains - user editable 3) Deform bones copying the transforms of IK/FK chains - users shouldn't edit this%%%

Joshua Leung commented

2011-01-14 00:32:16 +01:00

Changed status from 'Open' to: 'Archived'

Joshua Leung closed this issue

2011-01-14 00:32:16 +01:00

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Copy Location of Bones seems to lag and leads to animation errors #25624