Hi Zotoaster...
Thanx for the kind words!
JGC has got some inheritance and some polymorph'ing but its really not that thick in that regard so I never mapped it out in a diagram. I purposely tried to make each kind of DarkGDK thing really it's own mini class..
There isn't a scene graph either however if you look at the way the system is put together and how many of the demos show object counts etc. It wouldn't be hard to implement because the JGC does track all that stuff pretty good. Like counts of things etc - at least in the factory bits - but it's also designed to allow flipping between DarkGDK native and JGC things easily so folks aren't fettered / hand cuffed in any way trying to create.
--Jason