An FX file defines a DirectX 9 (DX9) shader. It is a text file created using the Higher-Level Shading Language (HLSL) standard. The DirectX 9 Shader material can apply DX9 shaders to objects, and display them with DX9 shading in viewports.

By default, DX9 shaders are saved in \maps\fx\ in the 3ds Max program directory.

Important: For a DX9 shader's parameter to be visible in the DirectX 9 Shader material's interface, the FX file must contain code to label the parameter, define its type, and (optionally) limit its range. (A few other UI settings are also provided.) You can find examples of files that contain this code in the above directory.

Note: The following Web page provides a specification for the DirectX 9 Shader material 3ds Max: http://sparks.discreet.com/knowledgebase/techdocs/searchable/techdoc_DXMaterialFormat/DxMaterial_Effect_format.htm.