Default sit pose

I've recently been reflecting on the SL default sit pose, which, as dorky as it looks, is quite a remarkable thing really. It seems to employ some kind of internal inverse kinematics, so that head, neck, shoulders, arms and upper body are free to move with the mouse cursor, while the hands are staying where they are on the lap. Very neat. It would be even neater if it were possible for a mere mortal animator to create an effect like that. Anyone know any secret passwords or handshakes or magical formulas to achieve that?

It's related to animation's priority. Animation can choose which bodyparts animate (no change between frame 1 & frame 2 for head => the head is not animated by the animation (so other animation can be applyed to the head (internal animation will be played (the head which follow the cursor is one of them) )

you can also read :
http://wiki.secondlife.com/wiki/How_to_create_animations

I know, but if you look closer at the default sit pose, you'll see that it's not just the head that follows the mouse cursor but the entire upper body including the arms, while the hands remain fixed.

Moreover the default sit actually starts with quite a complex motion of the avatar sitting down, which involves all joints including head and neck.

So I think we need to dig a little deeper for an explanation.

I believe (don't quote me on this) that several of the built in animations have 1)different priorities for different parts, & 2) seem to actually be series of animations played in sequence. at least this is what I get from my observations.

these things are hard (though not impossible) through stacked animations, serial actions, and occasionally some scripting... we don't get the same tools the lindens have to make these (and even if we did, the upload would 'optimize' much of it out)

as for the inverse kinematics, that is something you can take advantage of by only animating select parts of the body and not others... there are natural limits in some of the joints and things like head/body movement while sitting can be allowed by not animating those parts (and thus relying on the built in limits)...

from my little anim knowledge, I think its all to do with key frame 2, ie: if i want the head to move with the mouse loosely in anims then set the moment to 0 in the parameters if i want to to be static i set it to 1 - this works with any part of the model ur working on. I work in poser 5 hope it helps a bit

mm it's maybe related to the "avatar puppetering" projet :
http://avatarpuppeteering.com/

More information can be found in the wiki : http://wiki.secondlife.com/wiki/Puppeteering