how does ik in 2.4 work?

i only know the old way of making IK (making null bones). now i made the new way (making the tip of the bone chain be the IK), but now my problem is with the tip bone, the keyframes i put in the loc always give zero values. i couldn’t get the IK bone chain to animate.

please help

I think the easiest way (which is possibly the old way, with the null bone, I don’t know) is to create a bone which does no derforming, but is simply the target. I find it gives more control, even if there is a newer way . 8)

If I understand your question correctly, I think you’ll find the values in the numbers panel are “irrelevant” for an IK solver bone since it merely follows the target bone. Even with the new use-tip feature, you still follow something (target bone, empty or object) for genuine IK. The target is what you manipulate, not the solver bone. The target bone/object is what you key.

A similar question was asked a couple of months ago about rotation values for IK bones. The animation system knows what the solver bone values are but since they are calculated, not dictated, they aren’t displayed in the numbers panel.

… as I understand it :slight_smile:

what i mentioned in the null bone is that process of creating a new unparented bone as the target IK, as you mentioned. i’ve already been using that. i am just confused with how keys are put in the new targetless IK

ok, wait. what do you mean by numbers panel? i never mentioned anything about that. and what’s a solver bone?

and yes, i already know the concept of IK

Sorry, when you wrote that you were getting “zero values”, I assumed you meant in the numbers panel. You didn’t mention targetless IK in the first post and I haven’t really messed with it before.

The “solver bone” is the bone in the chain that moves all the others. Normally you have a target and the solver tries to always point at it. The null bones used to be the solvers and they dragged the other bones in the chain around. The “use tip” feature does away with null bones but not targets (which is why targets are still there as an IK option).

Anyway, I just had a try and you’re right - simply moving the tip bone and keying it doesn’t deliver the goods. However, if you move it then select all bones in the chain and LocRot key them, it appears to work. I guess that because it doesn’t have a target it’s like the auto IK option and requires that all bones be keyed because unlike normal IK, with target bones/objects, the whole chain can be influenced by the individual bones in the chain rather than being controlled entirely by the tip (solver) therefore, it’s location is actually determined by the rotation of the other bones.

If that makes any sense… :slight_smile:

sorry, my mistake too that i didn’t mention i was using targetless IK.

ok thanks AndyD, it seems i misunderstood the targetless IK feature in 2.4, the targetless IK setup technically isn’t really IK, since when it comes to animation, you still have to key every bone in the chain as if it was moved using FK. in other words, its just an FK chain, but moving the tip gives you a temporary “IK” setup. just a convenience feature i suppose.