llamamod/docs/reference/wad.md

WAD container

A level is one file wads/t1l<world>m<chapter>.wad. It is a flat list of chunks:

u32 total length
repeat:  u32 tag (four ASCII letters stored reversed: "OFNI" in the file = INFO)
         u32 length
         length bytes of chunk data

There are no checksums. When a chunk changes size, only the chunk length and the total length must be rewritten (format/Wad.java, tools/wadtool.py – wadtool.py list|extract|replace).

Chunks

In file order. "Loader" is the function in groove.exe that reads the chunk (dispatcher at 0x558960).

Chunk	Contents	Documented in
INFO, VERS	u32 1 each, ignored	–
WFPC	u32 feature flags of the level; they switch optional blocks in MAP and STPC on and off – never change them	Geometry
TEXT	texture pages, texture rectangles, texture animations	Textures
FONT	256 × 4 u16 glyph rectangles	–
SPRT	sprite list (u32, more with WFPC 0x100000)	–
NAME	u32 + level name (not shown anywhere in the game)	–
SMPC	sound samples of the level (cvg blocks)	Music and sound
AMPC	ambient sound data (ambi/VABp)	Music and sound
SRPC	references into the speech file music/<lang>.cvs	Music and sound
TRAK	world geometry: the tile models (render triangles + collision polygons)	Geometry
STPC	object models, skeletal animations and the strat code (object behaviour)	Geometry, Strats
MAP	the tile grid, vertex colours, visibility regions, objects, waypoints, environment zones	Geometry, Objects
LGHT	lights (directional and point lights for object models)	Objects
LNFO	u32 coins, u32 secrets: the totals shown on the tally screen	TestLevel
LGPC	dialogue texts in all languages + speech slots	–
END	end marker	–

Not every level has every chunk. The three chunks that matter for level building are TRAK, STPC and MAP; a new level takes everything else (textures, sounds, sky, fog, music) from an original base level.

The base-level idea

An object type exists in a level only if its code is in that level's STPC. MAP refers to a type by its byte offset into STPC – there is no global type id. So every custom level starts as a copy of an original level (default: Village 1, t1l1m001) and replaces geometry and objects:

• Python tools/levelbuild.py and Java levelbuild/LevelBuilder.java generate TRAK and MAP from a script and keep STPC, TEXT and sound of the base.
• The level editor stores only the difference to the base level and rebuilds the WAD from the user's own CD (notes/editor-format.md).
• Object types of other levels can be merged into the base's STPC together with their models, animations, textures and sounds – the editor's All worlds import and the arena use this (notes/editor-cross-import.md).

Level memory

The game loads STPC, TEXT (compressed pages + 20 bytes per texture entry), TRAK, MAP, LGPC and the strat pool into one 16 MB block (FUN_0041eea0); original levels use up to about 7 MB. See Engine facts and limits.