IK on deformers


I saw this forum post just by accident:

The thread is old, so it was locked and I was not able to respond.

Does this situation still applies in harmony 12? Is there not yet an easy way to do it?
I have been looking around for literature but I don’t seem to find it, has there been any development in this area?

Actually I do happen to have a solutions for this… my method it is kind of laborious but it does work… I have been linking the orientation values of the bones to the rotation angle of pegs, and using the IK chains over the pegs… this way you can control the deformer with IK… I just tell it in case someone is interested… If there is not already an easier method for it…


This post may be helpful to you:

Sorry for the extremely poor quality of the example, I don’t happen to find the right file so I just assembled a very sketchy leg…


Here there are 2 hierarchies: a deformer hierarchy, and a peg hierarchy. The rotations and positions of the pegs are connected and share the same value than the different bones, so if you use the transform tool over the deformer the pegs move along with the bones, and if you select the IK tool the deformer will move along with the bones… no need to switch things on and of or to detach parts of the body…

The end result enables you to deform the image with both FK and IK, and you just need to change the tool…

The setup is a bit tricky and it is not so perfect but it does the work… I think it would be very easy for the developers to make deformers and IK compatible if the nodes would be created automatically during deformer setup…

very interesting. i’ll have to give this a try.

Many thanks for the idea. Very clever.

I just wonder why Harmony doesn’t include a proper IK system for deformers.

if you have time can you post a screen shot of your network for this? thanks!

I’m sure gabriel, that you could probably make a script button to automate the process. :slight_smile:

I made a screenshot of the test, I warn you that the setup could be a little bit unpredictable and therefore frustrating because the accuracy of the trick depends of the location of the pegs and their orientation.
It would be much easier if toonboom developers would just integrate this concept automatically during the creation of the deformer so the orientation of the parts would be the right one… but it can be done manually.


The important things are highlighted in yellow, in order to link the values remember that you need to do 3 actions;

A) Open the bone properties and make the orientation value available for other layers to see, by clicking the white arrow and telling “local” (if it was local already most probably it wont become published, you should click the bezier editor button and then back to local). In order to make sure that it works you could for example look if the column became available in xsheet.

B) Go the the properties of the peg, select the white arrow at the left of the angle_z value and select Bezier/Bone_Orientation

C) Go back to the properties of the bone and this time we link the bone back to the peg: Bezier/Peg/Bone orientation

This ways the transformation seems to work in both ways… when you rotate the bone, the peg turns, when you rotate the peg the bone turns.

In the image you cans see a list with the values which I connected, I am representing the link with the “=” symbol

I did this a few times but I can hardly remember the best setup, I would need to make it a few times in order to remember… but it all depends on the hierarchy and the orientation, the position of the pegs and the orientation of the bones.

It is possible that if the hierarchy is not correct you would get some small gap between the IK bones and the deformer bones whenever you bend the leg a loot. this can be corrected by orienting the pegs properly and it is just cosmetic, when you move the mouse look at the drawing and not the skeleton, this way a small gap doesn’t really matter :stuck_out_tongue_winking_eye:

I forgot to say, the nodes in red are some crosses which I used in order to place the pegs correctly… it is tricky to place the pegs alone while they both inherit their transformation from eachother and grab rotations from the deformer, always look at the numbers and make sure that the result makes sense…

and, probably someone more used to cutout would for sure know a better way to do this, my workflow is just too unconventional…

thanks! appreciate the screen shot. when I link the peg up to the deformation orientation, the artwork suddenly rotates -90. not sure what im doing wrong, but ill play with it more when I have some time. thanks again!

That’s a quite expected behavior as you are plugin rotational values whose orientation could be just opposite, as I said it is tricky. Not just the first time, but whenever you forget the right order how to set up the things…
It all depends on the original orientation of the values. many times adding extra pegs at the beginning and the end of the chain helps keeping things in place, and attaching drawing to the pegs helps understand what is going on.

I am thinking to make a video, but I have not much time right now…

I will make a clarification, when I told you to add a peg at the top, I mean to add a peg above and rotate it in order to correct the orientation of the peg which is linked to the bone. So if things get messy you can use a peg for correcting orientations and a peg for controlling the thing… This will result in an ugly extra IK bone appearing but it does the job.

You could start working one bone at a time…

thanks again for the clarification!