Avogadro libraries provide 3D rendering, visualization, and analysis
aka ogre v2 - scene-oriented, flexible 3D C++ engine
GPU Raytracer from scratch in C++/CUDA
Lightweight and modular C++11 graphics middleware for data and games
A performant, flexible, and easy-to-use real-time 3D rendering engine
realtime 3d surface rendering library
Pear3DEngine is a modern and modular 3D development framework
PixelLight is a cross-platform application framework