Adding custom sprites

Sprites in DOOM are easy to edit with the right tool. Usually, they are exported/imported to and from .bmp images via DeuTex and it's Windows counterpart WinTex. On the Macintosh Port, graphics are edited on a slightly cruder interface via the Deimos program(the name standing for 'Doom Editing Interface for the Macintosh Operating System'). Any way, the editable sprites have a four-letter code, a letter key, and one or two rotations. A good example of this is the Imp's first walking frame lumps, labeled TROOA1, TROOA2A8, TROOA3A7, TROOA4A6, and TROOA5. Rotation-wise, if a lump adds another rotation to it's name, then the opposite rotation is a mirrored image of the same sprite image.