Problem with Final IK

[josemendez]

Ah, you mean ObiRigidbody!  Okay, I have applied one now (actually it did it automatically when I added a collider to the head, like you said it would). I also tried increasing World Velocity Scale a little and setting Update Normals to Skin. It seems to be a little bit improved, but it could be my imagination - it still does jiggle around when using IK.
You should be able to recreate it quite easily; Just get a character with hair (make a test one quickly with Fuse or something like that), then apply Full Body Biped IK & Grounder FBBIK components to this character, and setup Obi Cloth on the hair mesh like normal (but in Late Update sim order). Now try and walk on some stairs for a while, or very uneven terrain. Of course make sure the stairs (or whatever) are on a layer included in the Grounder Solver. If you find a reliable solution I'd be glad to hear about it.

Cheers

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!