Fxc

fxc is the DirectX Effects Compiler, a command-line tool that was part of the DirectX Software Development Kit. It compiles shader source code written in HLSL and the Effects format (.fx) into binary shader code for DirectX runtimes. For HLSL, it can target multiple shader stages such as vertex, pixel, geometry, hull, domain, and compute, producing either compiled shader objects or an assembly listing. For .fx files, fxc processes the techniques and passes defined by the Effects framework and can emit a precompiled effect binary (fxo) loaded by the runtime.

The tool is used by developers to build shaders that run on Windows with DirectX. Typical workflows involve selecting the appropriate shader target profile (for example vs_3_0 or ps_3_0), specifying the entry point, and directing the compiler to output a binary file or a disassembly. It was commonly invoked from the command line or via build scripts and distributed with the DirectX SDK or Visual Studio.

As DirectX evolved to DirectX 11 and 12, Microsoft introduced newer tooling, such as the DirectX Shader Compiler and the DXIL model, and the Effects framework was deprecated. Today fxc is largely a legacy tool associated with older APIs; some projects retain it for compatibility with older games and engines.

See also: DirectX, HLSL, Effects, DirectX Shader Compiler, shader model.