I have setup my kinect camera and now I want to track the wrists (or torso, or head for that matter). I see that I can draw the skeleton. But i would like to get the actual position vectors of these joints, because I want to calculate the speed.

Something like:

SimpleOpenNI context = new SimpleOpenNI();

PVector vector = context.getLimb(SimpleOpenNI.SKEL_TORSO).getPVector(); 

What function to call? 

Iterating over a RealWorldMap and storing all differences seem overdone for this purpose. 

Thank you.