True Reality (TR) is an open source LGPL Game and Simulation Engine written entirely in Standard C++ and OpenGL. It runs on all Windows platforms and GNU/Linux. OpenSceneGraph is used as its graphics engine, along with many other open source projects for support of various features.
Recreate a similar to D3D scene graph nodes and tree setup in TR
OpenSceneGraph should be wrapped in a trSG library, and from that scene graph classes should be created in trCore