Some IK help please

[lanza]

I have this character I'm rigging. I set up IK, it works fine. I'm now wanting to use the "twist" attribute. I connect it to a controler, works as expected. It workes fine on the positive side of the Grid, but on the nevative side it's inverted. I've tried everything, but still can't find a fix. I don't want to use "setDriven Keys".  

I was connecting it using the "Connection editor" then I tried using expressions. So I'm wondering if anyone can help me with some kind of a expression that would invert the valuse.

This is the expression I'm using, which works on the positive side (ikHandle3.twist = CRTL_RGT_WING.rotateX)

Thank you.  

[christianmassyn]

Souns like something is using the world up as a n up vector. This is not good practice rather use a locator that follows the rig to use as up. If not you can use utility nodes to make it work. Conditio node that will decide if it is positive or negative and a multiply node taht makes an negative positive.