Ik And Fk Setup?

[daikath]

I saw a character rig on a friends Max rig where he had a setup where the you could both drive the Control object via FK but if you grabbed the hand control, you also controlled it as IK without any switch.

I've been trying to do the same in Maya, making FK controls, parenting them to eachother and having the last one, rotation wise it works. But if I want to control to maintain the same position (translation value) and keep moving along with the IK movement, then it funks out.

Is there any way for the controller to keep moving with the elbow in the IK link, without any weird looping?

It would be really great for animation purposes to have both IK and FK at the same time.

[uiron]

the thing you saw in max was probably Character Studio. it allows putting a key on a whole arm, or leg, and saying, "this is IK key". you make another key and say that this is another IK key. interpolation happens in IK way then between those two, and if you add a third key which you want to be an FK key, then interpolation switches to FK-like behaviour.

while this is quite easy to pose (you can pose in FK or IK way as you want, grabbing and moving the wrist then rotating the elbow if you wish), it's rather hard to animate overlaps in elbow and wrist, for example, which is trivial, and essential in classic FK mode - because CS treats a limb as a whole, if you put a key, you put it on all three joints at once, and they have ONE interpolation curve TOTAL for EVERYTHING, meaning all rotate and translate attributes.

in other words, i can't even theoretically imagine this kind of setup being possible to do with standard nodes.

[daikath]

Ty for your answer . It was a custom rig, that I do know but this isn't easy to make.

I'll try the xform command to get world space coordinates of a joint in order to manually create a point constrain without a loop interfering with the entire arm.

I'll try to see if i can get it working at all and if it works well I'll post it here.

[joojaa]

Yes ive made such rigs. Its slightly painful, yes as it involves doing stuff mayas and dg gui doesn't like you to do natvely. I mean it involves rereouting input in a slightly unhealthy way, if you cant get your hand on api coder.

QUOTE
I'll try the xform command to get world space coordinates of a joint in order to manually create a point constrain without a loop interfering with the entire arm.

Its easier to do scritjob that updates connections as neccesery when you input and then just reroute the setkey command.

In any case what your suggesting is a bit tricky as it works fine if you just want to manipulate stuff. But not so much once you need to key it.

[daikath]

I'll only need to key rotation values, so I hope it works well. Because I can't quite visualize how i would go about doing it to update connections.

Since it already works by faking FK by parenting the IK controller to FK Elbow controller. I just can't get the elbow controller to stay in place of the elbow. Technically its not true FK, but it controls as FK.

Anyways if you can elaborate on your method Joojaa I would greatly appreciate it, since its clear you know more then me and can prove me wrong .

[joojaa]

QUOTE(Daikath @ 05/15/09, 04:09 PM) [snapback]307806[/snapback]
I'll only need to key rotation values, so I hope it works well.

Yes but then the ik cant interwene without killing mayas performance

QUOTE
Anyways if you can elaborate on your method Joojaa I would greatly appreciate it, since its clear you know more then me and can prove me wrong .

Think of it thisway, when you now design in maya you have one network. However NOTHING says the network in use for the user and maya playback needs to be the same network and if so only the playback network counts for anything. So what you do is always when user changes time, disconnect the animation rig, and place a more lenient rig in place. Then once user does something maya goes ahead and replaces the data to the real rig.

The rig that is in place when you playback MUSTbe one way only or you'll curse the day you were born when you go to render. So please test rendering stuff with your rig also because when it comes to batch you might be way off. So test all controls animatability in batch render before you start to animate serious stuff. You wouldn't be the first one to assume render is easy and go under*.

Oh its better if your joints dirve ik as if they were fk because that makes for more predictable motion. And you can get perfect fk solution with just 1 extra key wheras the other way youd be keying those parts where you need ik extra much

*or burn out because of 120h weeks of render wrangling This is by teh way WORSE.

[frogrobert]

I would suggest using Maya's built in FBIK rig. The rig is fairly easy to setup and allows both ik and fk types of interactions. It behaves similar to Motion Builder and may be hard to get your head around if you've never used MB. In the end, it can be quite nice to use. You can read about it in the docs.