PDA

View Full Version : Moving Individual Bones In IK



Columbo24
02-08-2015, 05:31 PM
I have an IK chain with bones. Why can't I move an individual bone? It's the one selected in the pic. Can you move bones in the chain especially at the end ,say if you had a hand you wanted to rotate?
Also when I parent an object to a null after it's been moved, the null pivot point isn't in the center of the object. If I use move pivot on the null it doesn't work. The only thing that worked is moving the object to the null pivot point and then parent. Is there something I should know when using nulls?
Finally, I'm doing a tutorial for LW 7.5 and in on it the last bone on an IK chain he has you create a very small bone to attach the null(Goal) to. Is this necessary now. CanI use the last bone andy have it's goal a null?
Thanks Bill

RebelHill
02-08-2015, 06:06 PM
If you've got something operating on IK control, then you cant manipulate with FK without turning the IK off.

Also, 7.5 is too old, there's too much different in LW these days... See here for the basic need to knows of IK.

https://www.youtube.com/watch?v=T2VYPnVIW0Y&index=15&list=PLTds3QePYrWEWipwKkLmyNT4Tf_JTigM2

MonroePoteet
02-08-2015, 06:36 PM
You can blend IK and FK (Forward Kinematics) on any bone by setting the blend percentage in the Motion Panel. Here's William Vaughan's tutorial on it:

https://www.youtube.com/watch?v=i-cHLpSmFAk

This will allow you to do some manipulation of bones independent of IK, but IK will still affect the bone motion / orientation based upon the percentage you specify. The default is 0%, which mean IK has full reign, and FK has none.

You might also look into IKBooster.

RE: the null parenting, sounds like you have "Parent In Place" set. If you unclick that, the object will move to center on the Null when you parent it. One of the sequences I use regularly is 1) unclick Parent In Place, 2) Parent the null to the object, 3) set Parent In Place, 4) set the null parent to <none>, 5) parent the object to the null. This initially moves the Null to the Object's pivot position (including rotation), and then parent the Object to the Null.

RE: the end-of-chain bone for the null, it just makes the actual goal of the chain at the end rather than offsetting it by the length of the final bone. For example, on a finger, it's usually the tip of the finger you want to guide with IK rather than the last finger joint. I usually set the Strength of the "goal null" to 0%.

mTp