Is there anyone in the world who understands Biped rotations?
Other than, say, the 10 or so developers who actively work on Max? Because I know for sure that there are a whole lot of people who don't, myself included.
We all (or at least those of us trying to work with scripting biped) know how Biped differs from other nodes, and how to "get at" the rotation, position and scale values. But I've yet to meet anyone who's shown me a successful way of transferring a simple rotation value from one node (a box or dummy object, say) to a biped. I'm not sure it can be done.
The Maxscript manual suggest it's simply a matter of using the inverse function, but it ain't so. My hunch is it is related to the whole hierarchy -- that is, you can't simply set a thigh to another rotation and expect it to work properly unless you first transform the COM and the pelvis (whether they need to be transformed or not -- somehow you have to take in that base rotation into account).
Yep, rotations are weird anyway, but are easily handled among nodes -- you can easily make a box follow the rotations of another box. You can even make a biped's part rotate to another biped's part -- but try to make it rotate to that box's rotation... no can do.
I can get agonizingly close -- either the whole leg rotates backwards (but otherwise behaves properly :>) or the thigh becomes detached and rotates while the calf and foot remain in place like a prothesis, but no matter what I try I can't do what should be easy... nor have I seen anyone else who can do it.
So here is my challenge -- someone write a script that does this, that takes a box that rotates in 3D space and rotates the thigh of a biped (and, of course, the lower parts of the leg to follow correctly) accordingly. I'm going to guess there will be no takers.