Miptex

Miptex is an 8-bit texture format used by Quake and GoldSrc. They can be stored individually with a .mip file, but most tools and engines expect them to be embedded in a BSP or WAD.

Miptex are always a multiple of 16, and contains the full-size texture plus 3 smaller mipmaps, although these mipmaps are only used by the software renderer (the OpenGL renderer uses the GPU to generate 32-bit mipmaps). Some programs also will use these mipmaps, such as TrenchBroom.

Half-Life extends the miptex format to add a dedicated palette, instead of relying upon an external shared palette. This is an uncompressed 768 byte array of 256 24-bit RGB values, like Quake's palette.lmp.

Technical

WAD2

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The header of a WAD2 miptex lump can be represented by the following C struct (from client/bspfile.h in the Quake I source code release):

#define	MIPLEVELS	4
typedef struct miptex_s
{
	char		name[16];
	unsigned	width, height;
	unsigned	offsets[MIPLEVELS];		// four mip maps stored
} miptex_t;

Note:unsigned is 32-bits.

It is then followed by raw 8-bit image data for each mipmap, at the offsets relative to the start of the file.

WAD3

Todo: Provide structs for paletted version of miptex.

Derivatives

Quake II encapsulates a modified version of miptex in a file format called WAL, which is always stored individually per texture and contains additional surface metadata for compilers. Variations of WAL, such as Daikatana WALs, M8, and M32, are used in other Quake II Engine games, and add some additional features.