Lightfeather is a 3D engine for Linux, Mac OS X
and Windows. It is designed to be easy to use but
still take advantage of the features of modern
graphics hardware.
GLFW is a portable framework for OpenGL application development. It handles operating system specific tasks such OpenGL window management, resolution switching, keyboard, mouse, and joystick input, timer input, creating threads, and more.
The Irrlicht Engine is a high performance real-time 3D engine written and usable in C++, and also available for .NET languages. It is completely cross-platform, using D3D, OpenGL, and its own software renderer.