View Full Version : How to add expressions after IK?

01-03-2004, 07:45 PM
I have a character with a few bones that are controlled by expressions. However, when IK is applied to the bones, the expressions stop working (not surprisingly). A good example would be Joel Dryer's Smartskin tutorial (http://www.newtek.com/products/ligh...n/smartskin.mov), that works great until IK is applied to the bones - then the expressions are completely ignored.

If I were to use Follower, there's the handy 'AfterIK' button. How do I add the same functionality to a humble expression?

01-03-2004, 08:12 PM
you can set this in the Motion Options for the object and choose Expressions in the Add Modifier menu. Then double click it and you'll find some options for Expressions with IK and the precious After IK option. Hope this works, bye.

01-03-2004, 08:57 PM
Well, thanks, that would work, except the expressions I've used are applied through the Graph editor 'Expressions' tab - where there is no 'AfterIK' button.

Is there an easy way to transfer the expression (with sub-expressions) from the graph editor to the motion options box?

01-04-2004, 12:34 AM
Not sure if this will help your problem but.. is autokey on when you atempt to move your character..if not , turn it on and try then.

01-04-2004, 01:03 AM
You can bake your Ik which will then convert it to keyframes that can be read by expressions.

And yes, in some cases, having autokey on will make it work.

01-04-2004, 05:28 AM
yup.. I loaded a rigged model in with ik and expressions and, when autokey was not active,the ik still worked but not the expressions. hope this solves the prob you were having, and if ne1 from NT is reading this.. im curious as to why autokey has to be active... seems like a strange bug.

01-04-2004, 03:38 PM
I habitually have autokey on anyway - so no, that's not the problem. The 'smartskin' tutorial I mentioned in my first post is a perfect example of what I mean. The expressions used in that tutorial work great when the arms are animated via FK - which is fine for 90% of my animation needs - yet if IK is applied to the arms, then the expressions (and thus, the elbow morphs) stop working.

If the same effect can be achieved using the expression modifier in the motion options box, how would one go about it?

The real sticking point for me is that expressions are like greek to me. The expression builder has been a real godsend, and I can't create them without it. But the expression builder is only accessible through the graph editor, where there is no 'AfterIK' button. Is it possible to get the best of both worlds?

01-06-2004, 04:02 PM
Im posting a followup to see if you found your problem.If so, could you enlighten us on what the culprit was?
I have'nt had this problem but ,if I do run into it,it would benefit greatly to know what to look for.
Best regards

01-06-2004, 04:18 PM
While there was no direct solution to the problem (like, an 'AfterIK' button within the graph editor expressions tab) - a quite brilliant workaround was devised by Julian Johnson in this thread in the Mac forum:


.. it involves using the motion baker plugin to create an extra channel to feed the expressions data from the IK'd bones. Well, he explains it a lot better than I do (even provides a sample scene) and it works like a charm. I hadn't realised that the motion baker provides live interactive data without the need to re-bake after the animation is tweaked.

Live and learn. :-)