Combining FK/IK

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  07 July 2010
Switching between FK/IK

I'm trying to rig an arm that has both fk and ik. I duplicated the joints of my arm twice, once for fk and once for ik, and then I parent constrained the main skeleton to these. I can switch between fk and ik, the only problem is they don't follow each other. For example I move the arm with fk, but the ik joints stay behind and vice versa. I'm new to rigging so not sure how to fix it.

Last edited by lsimpson : 07 July 2010 at 01:41 AM.
  07 July 2010
you dont have to constrain them. You just parnet the root joints all to the same master joint example would be the clavicle. as for not using constraints take a look at

there is a zipped maya file there that is a Stretchy FI/IK blend arm.
There is no one right way to do anything.
Only the un-explored ways. =)
  07 July 2010
Thanks Darksuit, I took a look at the scene file. I probably should have used switch instead of blend. What I'm trying to do is move the arm with a 100% IK, then switch to 100% FK without the arm changing position. Just go back and forth like that. As it is right now, I can move the arm with IK, but once I switch to FK, the arm will jump to another position, because the FK joints and the IK joints are separate. The main skeleton is constrained to both. Since they move independently, the main skeleton will jump back and forth between them whenever I make the switch.
  07 July 2010
if you are just trying to match the FK to IK that becomes a different problem.

one way to solve that is to run a matching script. ie

$rIKx = Arm_L_IK.rotate.x;
setAttrib Arm_L_FK.rotate.x $rIKx;

or something along those lines. That would essentially match the FK arms to the IK arms. Matching the other direction is a bit trickier.

It also comes down to what are you using it for and what is the expected end result.

Depending on the end result if all you care about is the FK arms being keyed after you have animated them with IK. Then you can simply bake the animation of the IK arms out, which would remove the IK chains and leave feks on the joints as if they were FK. Again it really just depends on the end result you are looking to achieve.
There is no one right way to do anything.
Only the un-explored ways. =)
  07 July 2010
dude u cn do one ting....orient constraint the ik nd fk bones wid the real bone chains...nd den play wid the weights of the orient constraint wid the ik/fk switch dat u made...i think it might help...
  07 July 2010
for FK IK switching you actually want to avoid constraint completely if you can. It will bloat the scene.

@sudipto1990 Orient constraint is rarely ever the right answer. It may work but, there are better ways to achieve the same effect with less overhead.

You can use PARENT Constraint (Translate and Rotate) on your Root Control, HandIK control, Foot Control. Then PARENT Constraint (Rotate) for the rest of the control.

Why not Orient Constraint...

From the Maya Character Setup book, Maya 2.0 Edition. Page 459-460.


Understanding Orient Constraints

An orient constraint matches the orientation of one object to one or more other objects. This Constraint is useful for making several objects orient simultaneously. For expample, you can make a group of characters all look in the same direction at the same time by animating one characters head and then constraining all the other character's heads to the head you've just animated.
There is no one right way to do anything.
Only the un-explored ways. =)
  07 July 2010
@darksuit....dude m just a begginer...i ve lots of tings to learn...i dnt knw every other i ve said wat i knw...dere may be 1000s of ways to solve a as a begginer...i need tym to learn ol dose ways....nd m learning....btw thnx for helping me regarding orient constraint...vl keep da fact in mind....thnx....
  07 July 2010
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