OpenGL 3D GUI Engine and/or assets [closed]

Answer 1

You might want to check this: http://www.libnui.net/

Answer 2

You might want to look at FLTK. Definitely still in development -- the most recent weekly snapshot was released today.

Answer 3

Qt allows all GUI elements to drawn into an OpenGL viewport.

Answer 4

Something like Crazy Eddie's GUI System?