Animated flat

The water effect on the outside area of the level Entryway is achieved using an animated flat.

Animated flats are a feature of the Doom engine where flats (textures used on floors and ceilings) are made to animate through several frames. One of the most common uses of this is to make a floor resemble a moving liquid, such as water or lava. They are often used to indicate damaging floors.

In the freely available Knee-Deep in the Dead episode of Doom, nukage (or green slime) is the only animated flat present, depicting substances the UAC has meddled with, while the episodes for the registered version add blue water, as well as blood and lava to give places a more hellish aspect. Doom II also adds molten rock for devastated and hellish areas and brown fluids to represent sewer water and other wastes.

The names of the animated flats are built into the game executable, so these can only be changed through string substitutions with a hex editor. Some source ports allow the animation tables to be changed and extended more flexibly.

Technical list of animated flats

Doom games

The eight animated flats normally available in Doom II.

In the Doom games, the built-in animated flats are:

First	Last	Game	Frames	General appearance	Descriptive name
NUKAGE1	NUKAGE3	All	3	Green liquid	Green slime, nukage
FWATER1	FWATER4	R, C	4	Blue liquid	Blue water
SWATER1	SWATER4	B	4	Blue liquid	Blue water
LAVA1	LAVA4	R, C	4	Red and yellow liquid	Lava
BLOOD1	BLOOD3	R, C	3	Red liquid	Blood
RROCK05	RROCK08	C	4	Large chunks in red liquid	Large molten rock
SLIME01	SLIME04	C	4	Brown liquid	Brown water
SLIME05	SLIME08	C	4	Pulsing brown liquid	Brown slime
SLIME09	SLIME12	C	4	Small chunks in red liquid	Small molten rock

At initialization time, the engine looks up each lump named in the First column above, and links it with all following lumps, up to and including that named in the Last column.

If any of the linked names is used as the floor (or ceiling) of a sector, then the engine changes it to the next linked name about three times a second (wrapping around to the first after using the last).

In the Game column above:

• All refers to all known versions after 0.5 (the latest known alpha version), including unregistered Doom.
• R refers to registered Doom, its press release demo, as well as the expanded retail release of the game, The Ultimate Doom. The entry is present in all executable versions since 1.666.
• C refers to the commercial game, Doom II: Hell on Earth.
• B refers to the Doom press release beta only. The blue water animation is duplicated as FWATER and SWATER in the beta, although these are not used in its three levels. The entry is present in all known executable versions except the alpha versions.

The Frames and Description columns refer to the graphics distributed with the original games. It is possible to replace the animated flats using a PWAD, although the PWAD must contain all the flats to be used in the animation, and not just those replaced. If an animation is replaced, the number of frames, and of course the description, may vary.

Heretic

All six animated flats from Heretic.

In Heretic, the built-in animated flats are:

First	Last	Frames	General appearance	Descriptive name
FLTWAWA1	FLTWAWA3	3	Blue liquid with glitter	Blue water
FLTSLUD1	FLTSLUD3	3	Gray-green liquid	Sludge
FLTFLWW1	FLTFLWW3	3	Flow of blue liquid	Flow of blue water
FLTTELE1	FLTTELE4	4	Rotating sign on a red background with white border	Teleporter
FLTLAVA1	FLTLAVA4	4	Smoldering coals among the ashes	Lava
FLATHUH1	FLATHUH4	4	Burning lava	Lava

See also

• Animated wall
• ANIMATED
• ANIMDEFS

Source

• Unofficial Doom Specs