RenderDotC (RDC) is a photorealistic rendering toolkit which adheres to the RenderMan(R) standard. Using the Reyes architecture, RDC supports advanced capabilities such as motion blur, depth of field, trim curves, texture/environment/displacement mapping, and programmable shading in the RenderMan Shading Language. The shader compiler included in the toolkit compiles shaders all the way to machine language for the highest possible performance.
The Nebula Device is a free multiplatform game engine currently running under Linux and Windows. It uses OpenGL and/or Direct3D for rendering and Tcl/Tk for scripting. Living C++ objects can be browsed and manipulated at runtime from the builtin console, or remotedly from a minimal terminal based console app. A powerful channel animation system allows any floating point attribute to be animated, and specialized animator classes allow things like realtime bone animation with weighted vertex skin.