Sprite

Sprites are graphics for the Doom Things.

Some things, such as weapons, ammo, and simple obstacles and decorations look the same at all times from all angles. These have a single sprite graphic associated with them.

Some things, such as certain powerups, look the same from all angles but have a changing pattern. These have several sprite graphics, displayed in a rotating sequence at a controlled rate.

The most complicated things, monsters and players, look different from different angles and can take on a different appearance depending on gameplay developments. Each of these has a set of sprite graphics, for which the display sequence is determined by the Doom rendering engine. Exploding barrels are also handled this way.

Each Doom Thing has a four-character sprite prefix defined for it, and all of its graphics are named beginning with this. The fifth character of a sprite graphic name gives the animation frame ordinal, starting at A and proceeding through the alphabet. (The sequence continues past Z, if necessary, using ASCII encoding.)

The sixth character of a sprite graphic name gives the rotation or rot. If it is 0, the graphic is used for all viewing angles. Otherwise, eight graphics, with sixth character ranging from 1 to 8, must be defined. The graphic 1 is used to draw a thing looking head-on; 2 through 8 are used as the thing is rotated in 45-degree steps counterclockwise.

It is possible to use a single graphic for two rots. For example, the name TROOA2A8 defines a graphic with prefix TROO for animation frame A rot 2. The same graphic, drawn in mirror image, is used for animation frame A rot 8.

Each sprite graphic is stored in the WAD file in Doom's picture format.

Replacing sprites using a PWAD file presents certain problems.

Additional detail is given in the Unofficial Doom Specs.