Inheriting controller influence instead of value (kinda like switching parents)

Hi everyone,

I posted this question up at the autodesk forums too but I always like getting ScriptSpot input.

I’m trying to do something similar to the idea of switching parents but I’m not sure that the Link Constraint will work in this situation. I’m basically trying to set up an eye rig similar to the one described in Stop Staring by Jason Osipa. I’m trying to get it so that most of the time the upper eyelid is influenced by the upper eyelid tracking bone, but when the upper eyelid gets close to the lower eyelid it hands the influence over to the lower eylid tracking bone.

I’ve tried Reaction Manager, Orientation Constraints and custom Script Controllers but the problem is always the same: When I begin switching “parents” the rotation of the “child” starts changing even though the parents are motionless. The child increases or decreases its rotation value to match the rotational value of the parent. What I want is for the child to keep its current rotation and change only when the parent does.

The reason I don’t think Link Constraint will work is because 1)Link Constraint is key based and I don’t want to have to set keys for the rig to work and 2)Link Constraint seems to function in an on/off fashion. I want to be able to gradually hand over influence from one object to another.

I’m attaching a picture that will hopefully explain it a little better. It may not even be possible but it appears that Maya can do it so I can only assume that there must be a way to do it in Max, too.

Thanks for any help. I’ve been trying to figure this one out for almost two weeks now with no luck:(