Well, this is a jPCT related forum, your solution doesn't use it. However, the basic idea is to take point in 3D space on which you want to "attach" the annotation to, project that into 2D screen space and then somehow blit the annotation as text on that position. Either that way, or you could "attach" another object at that point in 3D, make it inherit the actual object's transformations but render it as a bill boarded quad with the annotation's text rendered onto it. That has two drawbacks: It's much more complicated and it scales with the object which might render the text unreadable. Anyway, I've no idea on how to implement any of this in the context of your current solution.