Direct3D

RetroArchlibretro/RetroArch

A cross-platform frontend for the libretro API, enabling emulators and game engines to run as modular cores.

OgreOGRECave/ogre

A proven, modular C++ rendering engine for building high-performance 3D applications and custom game engines.

Diligent EngineDiligentGraphics/DiligentEngine

A modern cross-platform low-level graphics API abstraction layer and rendering framework for game engines and 3D applications.

Allegro 4.2liballeg/allegro5

A cross-platform game development library for C/C++ with multimedia, graphics, and input handling capabilities.

OpenSAGEOpenSAGE/OpenSAGE

A free, open-source re-implementation of the SAGE 3D real-time strategy engine used in Command & Conquer: Generals.