Normally all resources such as wall_textures, menu graphics and fonts, background music and sound effects are loaded from wad files. doomsday has a mechanism that allows replacing these resources with external resource files placed in specific directories. The files are called “external” because they are regular files and not contained within a wad file.
External resource files are easy to use. They do not require making changes to any configuration or definition files. As long as a resource file is placed in the correct directory, Doomsday will load and use it automatically. The external file's name (extension doesn't matter) must match the name of the lump that is being replaced.
External resources are divided into a number of categories. Each category has its own subdirectory under the Data\<Game>\ directory. The table below lists the resource categories and gives a brief description of each.
| Category | Purpose | |
|---|---|---|
| Textures | Textures for walls and flats (floors and ceilings) | |
| Flats | Textures just for flats (floors and ceilings) | |
| Patches | Graphics for menus, fonts and sprite frames | |
| LightMaps | Textures for dynamic lights | |
| FlareMaps | Textures for primary flares (halos) | |
| Music | Background music | |
| Sfx | Sound effects | Resource categories |
For example, sound effects for j_doom would be placed in the directory Data\jDoom\Sfx\.