IK folow FK, FK folow IK

[bobmorane79]

i try to make a arm IK/FK rig.
make the rig with the 3 skeleton (ik,fk,skin) is'nt a problem.
but a ould like that when i am in FK mode the IK arm folow the FK arm and when i am in IK mode FK arm folow the IK arm.
someone can help me ?
thank you in advance

[warpcat]

You could have scriptJob's running that when one item is transformed, another proc is ran that updates the position of the other. However, if you animate with auto-key turned on, you'll get a lot of unecessary keys this way, on the opposite controller.

[ithuriel2004]

I found it is easier for just have the float ability between FK and IK arm, creating a nice blended animation. Just simply use the switch via set driven to control the visability of the FK/IK controls
i.e FK=1 (on) -- IK controls visibilty=0(off)

Also note that the 3 skeleton approach isn't really needed, maya 5 and maya 6 both have in built FK IK blending/switching.

[gstapleton]

i use a 4 -chain skeleton (ik, fk, bind and another to drive the position of the pole vector locator so the limb won't flip). i wrote two lil' bits of MEL code that i made into shelf buttons that 'align' the fk to the ik joints before i switch (via an expression) and then another MEL button that aligns the ik to the fk before i switch back. i can explain it to you if you'd like, just let me know.

[bobmorane79]

yes i would like well that you explain me.

[gstapleton]

basically, the only thing you will need to add to the rig is a locator placed behind the shoulder at the same point as the pole vector locator, and group it under a node with its pivot point at the shoulder joint. parent that group node to the fk shoulder. for clarity's sake, i'll refer to that as locator as the twist locator.
then the switch script to align the fk to the ik should simply orient constrain the fk shoulder to the ik shoulder; the fk elbow to the ik elbow, and the fk wrist to the ik wrist. then the script should delete the orient constrain nodes immediately following.
to switch back from fk to ik, the script should point constrain the ik handle control to the fk wrist; and point constrain the pole vector locator to the twist locator to deal with the direction the elbow should be pointing; and then delete all of the constraint nodes immediately following.
i know it's fairly crude, but it works. i hope this helps.

[joojaa]

Okay, let me tell you guys something about why its not a very smart idea tohave the ik and fk switch so that they automaticlay are in the same position!

The reason is that while you get positional continuity in this you dont get any controll on how the speed flows into themselves, that is the min reson for a blending controll, so that you can asome the next position and adjust how the speed changes ito thet position.

A analogy of thsi si how stitching works on surfaces they can pe positionalystiched but tehy still wont look smooth.

And a jerky animation is poor at best, trust me humans are very good at noticing wrong accelerations, heck we do it all day long, ook at things move.

[gstapleton]

forgive me if i read you post wrong, but i respectfully disagree. if you have a limb setup like the one i use and the one, i thought, we were discussing, the bound limb is merely getting rotational inputs from an ik limb or an fk limb. so, the limb that is actually animated doesn't register one ioda of a change because the switch is done through an ik-to-fk switch attribute animating from 0 to 1 that solely triggers the change in input to the bound limb from the ik joints to fk joints or vice versa. oh, and if i read your analogy right you should know that stitching edges works perfectly if you attach and detach the surfaces together first to get isoparm continuity. good luck.

[joojaa]

Im merely answering the first original question where the usera askes for a system where the system hes not working on follows the one your working on and thus if you switch they would be in place allready, but as i pointed out you wouldnt want that kind of switch because theres no controll over the change (youd need to do as much work anyway).

Im not saying anything about the righs discussed after the fact.

You want the ik be in the next animation pose wan you strat merging it in so that you can controll how the movement comes into thet place.

Yes yes that works in my anbalogy as well as setticng stich to tangential continuity, however theres no animation function that can repaeat the process of making 3 movements derivates and d their derivates automaticaly match, as there are too many solutions.