IPO Drivers with Bones

(Aligorith) #1


How should the new IPO drivers be used to control an eyelid using bones?

In my setup, there is a bone that points along the negative(?) y-axis. It is used as the target for a constraint which moves an eye. Now, when rotating this bone on its local z-axis, the eyelid should move -> close when rotated downwards (pointing in the direction of the negative z-axis), open widely when rotated upwards (pointing in the direction of the positive z-axis). I’ve got two ‘shape’ keys for the eyelids in the closed and wide positions.

When I tried to get this working, the result would always be overdone.

Can someone provide a working example in which the the eyelid behaves in the way described?


(AndyD) #2

I left this alone for a while because it’s all a bit new to me but since no one’s answered I’ll offer some things to consider.

If I understand you correctly, you have a bone floating in front of the face. If you move this bone around, the eyes follow it (look at it). And, you want to use this same bone to also control the eyelids if you rotate it?

If this is what you want, then I don’t think you need shape keys. You can have a bone in each eyelid. Set up vertex groups as usual and use weight painting to vary the deformation if need be. These lid bones would have an action constraint applied targeting the floating control bone. I can’t explain the action constraint process well enough, though it’s pretty straight forward (you’ll find action constraint threads around here - one by Douas, I think, explained the fundamentals quite clearly).

You can’t use a bone as an IPO driver for another bone in the same armature, so constraints are probably what you’re after. Gabio has recently posted some links to an arm he made using constraints, this may also help.

The main reason I say you don’t want a shape key is because a closing lid usually requires a curved motion (an arc) but shape keys (or RVKs) are linear and this means your eyelid won’t slide neatly over the spherical eyeball.

(Aligorith) #3


You can have a bone in each eyelid.

I used to do that. However, it is difficult to obtain a good deformation, even when using an eight-bone setup for that.

Anyway, I’ve fixed the problems I was having, by using the option to map the curve one to one (or something like that).


(AndyD) #4

I guess all eyes and eyelids are different but I did one recently using a single bone and some careful weight painting to ensure the major deformation occured at the centre with very little to none at the edges. It took a little while to set up (but it’s still new to me remember) but work’s quite nicely.