Reverse canted leg IK problem

[orko]

Hi all,

I've got a fairly straightforward problem. I'm making a reverse-canted leg where the ankle position is controlled by rotating the foot/toe. You know the setup: the ankle locator is a child of the foot locator...

Well, I'd also like to control the Twist function for the entire leg's IK (not just from the thigh to the ankle). Problem is, the IK is broken at the ankle (so that you can pivot the foot and have the rest of the leg react). Thus no Twist functionality from the top all the way down to the toe.

I'm sure some of you have done something like this before. Anyone know how to solve this one?

Many thanks,
-Oldi

[izzy]

I believe Alex at Gnomon talked about a solution to this type of thing
in his tutorial about proper arm IK. (lower-arm rotation without the whole arm rotating with it)

In his tut, he shows how to add a joint to an already linked/IK'd bone structure.
Then he goes about making the joint rotate on separate axis' than the surrounding bones.
(Don't quote me on that, I havn't been there for a while.... sorry Alex:)

Check the Gnomon Workshop for the tut on IK arm setup, or something,
and I think it may lead you to a solution to your prob:)

Also, have you tryed grouping the whole leg that you want to "twist",
so as to give you a "new" adjustable rotation pivot point?
(Not sure if that will work though.....)

Izzy
VFX Artist | Maya Animator
Arena Digital Effects
http://www.arenadigital.net

[yellowsayshello]

Are you using the reverse foot method, or some other way of controlling the foot? If I understand correctly, you wanna use the twist function in the RP solver, but also want to rotate the entire leg and foot, which of course the twist function won't do. Do you have a pole vector constraint? set one up in front of the knee, and parent it to the reverse foot (or whatever foot control you have setup). Then when you rotate the reverse foot in 'Y', the whole leg will rotate with it...this is independant from the the twist function, so you can use that too (it will compound of course, though) Put all the controls on the reverse foot (like a dynamic attribute called 'twist' or something) and connect it to the twist attribute on the RP solver, so you don't have to select the IK handle anymore.

10 PRINT "kemijo is the best"
20 GOTO 10

RUN

[orko]

Thanks guys. Unfortunately, neither of the solutions worked in this case. The IK handles prevent the pole-vector from working from thigh to toe for the same reason that the whole-leg Twist function doesn't work. As to the Gnomon solution, it doesn't seem to offer any alternatives--but I could be misunderstanding it. I appreciate the input though--it'll help me solve the problem. I'm still working on it...

-Oldi