Direct3D
Direct3D is a graphics application programming interface (API) for 
Microsoft Windows. It is part of 
DirectX.
GoldSrc engines ships with a software renderer, OpenGL and initially, Direct3D 7, prior to it being removed in 2013 after SteamPipe update. Unlike OpenGL (since detail textures support was added in 2004 with the release of CS:CZ) and like the Software renderer, it doesn't seems to have issues with overbright lighting.
Source mainly used Direct3D 9 (Shader Model 2) renderer, which later was upgraded to support Shader Model 3.0 (in all games since 
), but offers backward compatibility with older GPUs using DirectX feature levels. Some third-party engine branch like 
Titanfall branch and 
Strata Source use Direct3D 11 instead. Throughout 2020-2022, nearly all of Valve games also added support for Vulkan renderer on Windows, using DXVK to translates D3D9 to Vulkan. Enabling Vulkan translation will require the "-vulkan" launch option (except in Portal with RTX and upcoming Half-Life 2 RTX).
Source 2 mainly uses Direct3D 11, but also has options to use the Vulkan renderer.
Id Tech 2 Engine (WinQuake) Direct3D
Features
Support for windowed video mode
Missing Features and Limits and Problems
- Rudimentary Shadows
- 32-bit color
- Many resolutions from vanilla quake are not unsupport
See also
- DirectX Versions - list of DirectX feature levels
- OpenGL
- Vulkan, another graphics API, successor to OpenGL.
- Software renderer