.MDL File Format – Textures and geometry

Textures

numtextures records of 80 bytes at textureindex (mstudiotexture_t). When the main file has none, they are in the T.mdl companion file.

At index are width × height bytes, one palette index per pixel, row by row from the top, followed straight away by the texture’s own palette: 256 colours of 3 bytes, red, green, blue (768 bytes). Each texture has its own palette.

Texture flags

Skin families

At skinindex is a table of 16-bit texture numbers, numskinfamilies rows of numskinref each. A mesh names a slot (its skinref), and the entity’s skin number picks the row, so a model can swap whole sets of textures, such as a scientist’s different faces.

Body parts

numbodyparts records of 76 bytes at bodypartindex (mstudiobodyparts_t). Each body part shows exactly one of its models, such as a head with or without a helmet.

The entity’s single body number encodes every part’s choice: part p shows model (body ÷ base) mod nummodels, with whole-number division.

Models

nummodels records of 112 bytes at the body part’s modelindex (mstudiomodel_t).

To place a vertex, transform its position by the current matrix of the bone named in its info byte. Normals turn with their bones in the same way.

Meshes

nummesh records of 20 bytes at meshindex (mstudiomesh_t).

Triangle commands

At triindex is a list of 16-bit commands, as in Quake II’s MD2:

Each vertex in a command is four int16 values, 8 bytes:

FD FF                         fan of 3 vertices (−3)
05 00  05 00  10 00  20 00    vertex 5, normal 5, s 16, t 32
...                           two more vertices
00 00                         end of the list