View Full Version : Weird behavior of my rig

01-13-2012, 12:05 AM
Could anyone spot what's wrong with my rig? It's very simple one.
The left arm doesn't work right when I rotate Chest control.
I've been looking for hours but cannot find what's wrong! Help!

01-13-2012, 03:18 AM
Its the fault of the dependency loop that exists between the spine bones, and the chest control null.

If you turn off the nulls sai position behaviour to stop it following the chest bone position, it works fine.

However, Im not sure exactly WHY this happens. LW detects dependencies on an item level only, not channel, and despite the setup, there is actually no interference between having the bone follow the nulls rotation, and the null in turn following the bones position... in short... it SHOULD work as you have it.

I also cant quite fathom why its only then affecting the IK of the one arm, and not both. I suspect its likely a lil bug in LWs motion system somewhere. But anyhow, there's the fix for u, Ill investigate further whats going on some later point, cos something funny is def up thats worth looking into.

01-13-2012, 04:01 AM
Thank you for taking your time, RebelHill. You're very helpful.
I've made several character using this kind of control and had no issue until now.
If I delete the left side and mirror the right side, then the right side went wrong.
Maybe I could built new arm rig but I am worried because I don't know if this problem comes up again.
Meanwhile I'll take your advice and use bones to rotate. Hope it's gonna be solved.

01-13-2012, 05:23 AM
The Aliens have invaded your computer...


Ya that is odd.. the behavior
LW busy with Animation ScreamerNet will look at it tommorrow...

01-14-2012, 01:16 AM
Hi, zapper. I'm really stuck at this. If you find anything please let me know!

01-19-2012, 09:13 AM
Okay, I reported this as a bug and here's reply.

"You need to "pre-bend" your bones in anything that is to be driven by IK. This gives the math a "predisposition" on which way to bend it."

01-19-2012, 11:38 AM
Okay, I reported this as a bug and here's reply.

"You need to "pre-bend" your bones in anything that is to be driven by IK. This gives the math a "predisposition" on which way to bend it."

Looks like this is not the problem in this scene.

There's some kind of evaluation problem.

The rig structure is a little "original"...but the fact that only one arm works, clearly shows the presence of an evaluation problem.

We'll look into that.

01-19-2012, 12:36 PM
Ah... I ws thinking the same thing, its peculiar. LW flags a dependency, which shouldnt cause a problem here, cos its an item loop, not a channel one, so has gotta be a bug in evaluation.

I was about to pick it apart and report it on further, but since you caught it lino, that'll be good Im sure.

01-19-2012, 12:57 PM
Thank you, guys. Much appreciated!

03-05-2012, 09:05 AM
Can we get a bug report on this so we can assign and address the issue? If you have already entered a case, please let me know the case number. Thanks!

03-05-2012, 10:21 AM
done. 44605

03-06-2012, 01:40 AM
Those dependency warnings are not there to just annoy you. Item loops are bad for the IK evaluation. It needs to be able to order the items based on their dependencies, otherwise a bunch of stuff is not guaranteed to work right.


03-06-2012, 05:57 AM
But its previously been said that some things flagged as dependent should still work and can be ignored where no "true" dependency exists... like 2 items targeting each other, etc. And even so, if it is causing a mishap in the IK solver that lies further down the hierarchy... why does it only affect one arm... and not the other?