A world editor for HGE game engine written in python and uses OpenGL.
an interactive 3D viewing program
3D game engine for C and C++
Pear3DEngine is a modern and modular 3D development framework
https://github.com/horde3d/Horde3D
Multi-Language Wrapper Collection for the Irrlicht Engine
Game engine supporting many 3D/2D formats and graphic effects
A C++ library to easily create GUI-editable objects