View Full Version : 3ds max : Arm rig IK/FK switch

05 May 2007, 02:58 PM
Anyone knows how to rig an arm so that it has an IK/FK switch? or where can I get a tutorial..I understand its about using to sets of bone chains, on FK and one IK..



05 May 2007, 06:20 PM
Three actualy, one IK one FK one that is orientation constrainted between the other two.

05 May 2007, 07:33 PM
thanks for your help!...but its a bit unclear still..are the 3 chains going to deform the mesh or one deforms and the other two(IK/FK) cause movement to the deforming chain?
and how is the setup of the orientation constraint? the third chain contrained to the IK anf FK chain?



05 May 2007, 08:57 PM
You are right on all assumptions. Sorry I don't have time to do a detailed explanation. but you are right on the money so just give it a go.

06 June 2007, 05:17 PM

Yah, so far PEN is correct and you are on the right track. Just constrain the 3rd arm to the FK and IK versions and set up the switcher in the reaction manager (I used a slider helper as the master object). It was a pain trying to figure it out the first time, but now it makes total sense.

06 June 2007, 06:20 PM
Just as a side note, I would avoid using reaction manager where you can. If a simple wire parameter will work that use that. RM is far slower as it has to calculate function curves internaly to give you a result. This most likely in this case is not what you want. WireParams are fast and simple and will not cause you any issues.

06 June 2007, 06:55 PM
cool, thanks for the heads up PEN. I'll have to figure it out how to set it up with WP's instead of the RM. Is this something you'll cover in your Advanced Rigging DVDs? (setting up IK/FK arms & legs?). Anyway, I can't wait to pick it up.

06 June 2007, 07:05 PM
Don't know how common this method is, but it's how I handle IK/FK switch. (oh hello there PEN control objects)

The three controlled objects are the IK chain, hand bone, and elbow orientation object. Two sliders control the position/rotation weight.

The elbow control ends up being linked directly to the FK lower arm control, so it'll move around just like you'd expect. I anticipated problems with this but there actually haven't been any.

You could use just one slider for the FK/IK switch, but I set up the character to have multiple targets - different weapons, mainly, including a holstered handgun which can stay with the character, float freely with IK, or be tied to the FK controls. It plays really well with things like that.

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