View Full Version : Spline Ik/Fk

05 May 2007, 03:19 AM
Hey guys,

I have been trying to figure out how make a spline that uses both spline Ik with Fk controls.

I have tried this with a single set of bones and many constrains, but it doesn’t seem to work for me.

As you can see on the image below the fk controls work and the Ik spline also works, the thing is whenever I move the spline Ik it leaves the fk controls behind, and this makes it unusable. Perhaps I'm going about this the wrong way.

I have been thinking of just starting from scratch and build 3 different chains and set them up as an ik/fk arm would be done, the thing is I wouldn’t use the possibility to blend between ik and fk, rather just "switch" which would realign the controllers and switch the weights as I press the Ik/Fk button. I think this method would probably work.

But before I try this I just want to hear what methods you guys use or how you guys approach this. Maybe then I could get an idea of what I should be aiming to.

Thanks all

05 May 2007, 12:05 PM
What have you tried so far?

I don't know what you expect to happen but if you want both to always be active and one to follow the other then what you end up with is a dependancy loop. One has to be parent to the other so that one will move the bones away from the other.

a common way to handle this is to parent all the IK controls to the FK. So that the FK drives the IK and the IK will pull away from the FK. The oposite can be done as well.

05 May 2007, 10:19 PM
Thanks for your input Paul.

Well It's my first time trying to create a spline that handles both ik and fk methods.

The way I tried it was creating a spline ik that is basically the same way you make yours in your 2nd DVD, then I created fk controls for every bone on the spine except for the nub.

I created 1 extra helper for every spline helper and aligned to them. So now I would have 3 helpers and each spline joint. (The spline helper, the path constrained helper, and my newly created helper: this one was made to zero out the rotations of my ik and fk controllers).

Then I basically linked the slpine helper to respective CTRL and the CTRL to the newly created helper (this was done to both my fk and ik CTRLs), and that would zero them out.

Then I just went down the chain and started linking the newly created helpers to the CTRL that was underneath them and so on.

What this gave me was the possibility to rotate the helpers which the bones are looking at, according to the CTRL that was underneath them.

I was just trying to figure it out on my own but I'm stuck and I just felt that there was probably a better way to go about this.

Thanks for the advice though I will try the method you mentioned.

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05 May 2007, 10:19 PM
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