I've got a Bicep bone and a Forearm bone. I also have a BicepBulge bone
perpendicular to the Bicep bone. Using an expression for the length of the
BicepBulge bone as follows:
abs(Forearm.rot(Time).p / 10)
Not necessarly the exact equation I want, but enough to observe the effects
Anyway, assuming I have a full IK chain from shoulder to hand, and IK goals
for the hand and elbow, I would think that the length of BicepBulge would
change as I move my nulls to bend my arm, but that doesn't happen. If I
keyframe the movement of my arms instead of using IK, then the length
changes more or less as I would expect. Also, I can workaround by creating
keyframes for the Forearm bone everywhere there's a key for the IK goals --
if I move my goals, the keys all auto-update, and the bone length behaves.
Still, I'm surprised that with pure IK (without duplicating keyframes for
the Forearm bone), expressions don't seem to "see" the bones moving at all.
Is that the way they're supposed to work?
Yesterday is tomorrow.