G3D is a commercial-grade C++ 3D engine. It is used in commercial games, research papers, military simulators, and university courses. G3D supports real-time rendering, off-line rendering like ray tracing, and general purpose computation on GPUs.
Fluid simulation by Charles Cao and Kefei Lei
Anime Robot from Hardware Determined Edge Features
SuperShader "Models" demo for advanced GPUs
Renaissance-style racing by Kyle Whitson and Aaron Schwartz
Images by Inq Games using a G3D-based engine