A layer built on top of the Insight Toolkit (ITK)
FlightGear Flight Simulator: free open-source multiplatform flight sim
crossplatform multithreaded object-oriented render and audio engine
HARFANG 3D source code public repository
A small C library for building user interfaces with C, XML and CSS.
A Realistic and Rich 3D Environment
Imagin Raytracer is a multithreaded command line raytracer
simple 3d scene viewer for windows/linux/android
Multi-Language Wrapper Collection for the Irrlicht Engine