Finally playing with the new inverse kinematics support in #Godot 4.6.

Unfortunately, it seems that pole targets are only supported for two-bone IK! So that won't work for elbow joints in #SnekStudio (my open-source #VTuber software) because VTuber model arms tend to be more complicated than simple two-bone chains due to twist bones and such.

So I went ahead and implemented something a little closer to #Blender 's pole target support, which works as its own SkeletonModifier3D-derived object, allowing it to work with other types of IK chains.

Hopefully this will let me replace SnekStudio's existing IK code, which still feels very prototype-y, even after one or two significant overhauls.

I've been waiting for the new IK stuff for a while, but it looks like there are still one or two functionality gaps to fill in before I can use it to entirely replace the DIY IK system in SnekStudio.