View Full Version : How to work with a triple arm setup?

05 May 2003, 05:54 PM

I've created 3 arms for my rig. The first one uses FK, the second one IK and the third is the final arm, which deforms the mesh. The third arm inherits the transformations from the first two. Also I've also put in a slider so I can graduatly switch between FK and IK .

I've read a few things about this technique, but one thing I don't quite understand is how to "lay them out". My 3 arm setup works, but where do I leave the arms? Do all the 3 arms originate from the same shoulder? Do you hide the FK arm when animating IK and visa versa? If you switch back from FK to IK, how do you do the transission? Do you align the IK arm back so it roughly matches the FK arm and then toggle back?

I hope someone can enlighten me a bit on this subject. Thanks.

05 May 2003, 06:35 PM

Well, the 3 arm set up is cool.. IF you need it.. don't go setting it up if you don't really need it..

As far as using it..

You can either attach the FK-Shoulder, IK-Shoulder and Real-Shoulder to the clavicle (by parenting it)

You could also point and orient constrain them so that they are not part of the same hierarchy.. but that is a little bit more complicated, since you would have to use different null objects, etc.

As far as using them goes.. you mainly want to animate with FK to get nice arcs, etc.. if you want to switch, all you would have to do is place the IK harm where you want the transition to be.. it doesn't have to be perfectly on top of the FK one, since you can do a transition over a few frames (3, 5, 10 if you want to and you won't notice the transition since it'll be smooth)

I like to add an extra set driven key where when I'm using FK, the IK is hidden and same viceversa.. it's just a little easier to understand what's going on and you don't make mistakes on choosing the wrong one. I also have the Real bones templated so I can't select them

I hope that helps


05 May 2003, 09:50 AM
Could you provide some links to sites containing some information about this. I've never heard of such rig.

05 May 2003, 05:09 PM
You can see one on my site on


05 May 2003, 01:40 AM

In they have an excelent video tutorial for the IK FK arm rig, but this one is only for member sponsors (which BTW is worth it!).


05 May 2003, 07:45 AM
Thank you Goosh. I was just curious the idea of such arm. Now I know, but while I use Charcter Studio I've no need of it.

Nice site by the way :thumbsup:

See you

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