Problem with Final IK

[Deckard_89]

Hi,

Found time to test this out. Works fine for me (tested it in the sample CharacterCloth scene). Just make sure that ObiSolver is set to execute after FinalIK in the script execution order panel.

If FIK executes after Obi (FIK places itself as the last thing to execute automatically), it will reposition the cloth after the simulation every frame which leads to jittering (cloth falls due to gravity, FIK moves it back up to meet IK constraints, cloth springs back up and falls, FIK moves it back up...etc).

Keep in mind that most IK methods make adjustments every frame to the raw animated bones, unlike physics engines (like Obi) which use the previous frame's output as input for the next frame of simulation. This means that the order in which you apply them is extremely important since any sync issues won't manifest themselves as 1-frame delays or similar stuff (which would be hard to notice), but will haunt you every frame instead.

What you're after is this sequence of events per frame:

- Skeletal animation poses the character.
- FIK moves the bones to their right position, to meet IK constraints.
- Obi simulates the hair mesh using the IK-corrected bones as input.

So, set ObiCollider and ObiSolver scripts to execute last, after all Final IK stuff.

cheers!

Thank you, this seems to have fixed it! You might want to make a note about the script execution order in the manual for people using Root Motion plug-ins, because for me Final IK was indeed set to be last, and I never would have figured that out if you hadn't told me.

Thanks again