action constraint

Hello all Got my 2 cents question for today.
Did action constraint can control influence slider of other constraint?

No. For that, use drivers instead, preferably constraint-local-ipo’s in this case.

Neat! I like the way you think dagobert! :yes: I just learned something!

Yes you can! However, as Aligorith mentioned, it is a very indirect and bizarre setup… so I can’t currently imagine a scenario where it would be desireable! But it’s always nice to know what can be done!

I’ve attached a file to demonstrate. The bone on the left has the action constraint which is driven by the control bone, the bone on the top has a rotation constraint that is driven by the action constrained bone. If you move the CONTROL bone in positive Z, the action constrained bone is driven, and in turn the rotation constrained bone is driven.

This reminds me of a Rube Goldberg type of setup, with one object driving another, driving another etc… all to do something simple :slight_smile: I wouldn’t use it on a character as far as I know…


actionConstraintDrivingAnotherConstraint.blend (157 KB)

Hmm… must’ve been too long since I last touched the constraints code XD

well be able to control influence slider more easily would be a great thing and action constraint seems easier to set up than drivers.
Bartius crouch make me a constraint that is able to collect influence of other constraints in the scene. and that s great. but due to some few blender bugs it not perfect (no refresh if you dont move something and not so easy than normal constraint).
but may be i m wrong about drivers.


to be clear, I still needed to setup a driver on the rotation constraint! The action constrained bone is a driver for the constraint. It’s just that the rotation for the driver bone is controlled by the action constraint instead of being manipulated directly…


It would be much better to drive the constraint directly, as Aligorith mentioned…

I just did this because it’s a fun little quirk! But like I mentioned… it’s a roundabout way to an otherwise simple solution. So yeah… don’t do it this way! :wink:

If i use ipo drivers the driven is not update exept if you scrub the timeline. It s really annoying. Did you know if there is an option to force refreshing ipo drivers?
At least action constraint are refreshed in real time. It could be cool if you could control influence trhought action so as to get real time.

Yes, you can get IPO’s to update in realtime. You just need to click the little ‘shark attack’ guy in the IPO editor to turn him off (which disconnects the curves from the action editor - making it a realtime evaluation instead).

I wrote a post about it in the rigging thread if you need more info!


This tip is just crucial!