*.geom

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The format was disassembled by Haper (not completely disassembled, adjustments are needed)

About

Contains all visible map geometry. It contains all vertices with normals and coordinates for textures and indexes for building geometry, as well as synchronization.

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Technical information

The file consists of the following blocks

	Block code
Map compiler version	1
Vertex description	9
Indexes description	10
Synchronization description	11

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Types of variables

Type code	Value
1	DWord(4) + DWord(4)
4	Byte(1) + Byte(1) + Byte(1) + Byte(1)
6	Word(2)/32768 + Word(2)/32768
7	(Byte(1)-128)/128 + (Byte(1)-128)/128 + (Byte(1)-128)/128 + (Byte(1)-128)/128

Map compiler version (the block is the same for all maps)

	Value	Size
Block code	1	Word(2)
Data compression (0 - no, 32768 - yes)	0	Word(2)
Block size (bytes)	4	DWord(4)
Version number (same for all)	13	DWord(4)

Vertex description

	Value	Size
Block code	9	Word(2)
Data compression (0 - no, 32768 - yes)	0	Word(2)
Block size (bytes)	4	DWord(4)
Number of vertex description blocks	-	DWord(4)
Vertex description block	-	-

Vertex description block

	Value	Size
Beginning of a new block	0	DWord(4)
Beginning of the vertex format description	2	DWord(4)
Vertex format	-	-
End of vertex format description	255	DWord(4)
Beginning of the vertex description	17	DWord(4)
Number of vertices	-	DWord(4)
Vertexes	-	-

A few words about the vertex format

As you already know, there are several vertex description blocks in the file. Not all objects in the game are the same: you have to specify coordinates of lightmaps for brushes, and coordinates of textures for trees can be simplified. Therefore, vertices specified in different blocks may be different. The vertex format is specified using several structures - this is the standard D3D vertex buffer format. That is, the file contains ready assembled vertex buffers for D3D:

	Value	Size
???(always zero)	0	Word(2)
Offset	-	Word(2)
Type of variables	-	Word(2)
What the variables describe	-	Word(2)

At the very beginning of any vertex are the coordinates of its placement, so the vertex format does not include a description of the coordinates. There are only three vertex formats in the 2215 maps:

Vegetation

	Value	Size
zero	0	Word(2)
Offset	12	Word(2)
Type of variables	4	Word(2)
Normals	3	Word(2)
Light factor(?)	?	Word(2)
Offset	16	Word(2)
Type of variables	4	Word(2)
Tangents	6	Word(2)
Texture corrector X coordinate	0/1	Word(2)
Offset	20	Word(2)
Type of variables	4	Word(2)
Bi-Tangents	7	Word(2)
Texture corrector Y coordinate	0/1	Word(2)
Offset	24	Word(2)
Type of variables	7	Word(2)
Texture coordinates	5	Word(2)

Thus, the total length of one vegetation vertex equals 32 bytes.

Brush

	Value	Size
zero	0	Word(2)
Offset	12	Word(2)
Type of variables	4	Word(2)
Normals	3	Word(2)
Light factor(?)	?	Word(2)
Offset	16	Word(2)
Type of variables	4	Word(2)
Tangents	6	Word(2)
Texture corrector X coordinate	0/1	Word(2)
Offset	20	Word(2)
Type of variables	4	Word(2)
Bi-Tangents	7	Word(2)
Texture corrector Y coordinate	0/1	Word(2)
Offset	24	Word(2)
Type of variables	1	Word(2)
Texture coordinates	5	Word(2)
zero	0	Word(2)
Offset	32	Word(2)
Type of variables	6	Word(2)
Lightmap coordinates	261	Word(2)

The total length of one brash vertex is 36 bytes.

Entity

	Value	Size
zero	0	Word(2)
Offset	12	Word(2)
Type of variables	4	Word(2)
Normals	3	Word(2)
Light factor(?)	?	Word(2)
Offset	16	Word(2)
Type of variables	4	Word(2)
Tangents	6	Word(2)
Texture corrector X coordinate	0/1	Word(2)
Offset	20	Word(2)
Type of variables	4	Word(2)
Bi-Tangents	7	Word(2)
Texture corrector Y coordinate	0/1	Word(2)
Offset	24	Word(2)
Type of variables	4	Word(2)
???	10	Word(2)
zero	0	Word(2)
Offset	28	Word(2)
Type of variables	1	Word(2)
Texture coordinates	5	Word(2)

The total length of one vertex of an entity is 36 bytes. Based on this, we get, for example, this view of the vertex:

Brush

	Value	Offset	Size
Coordinate X	30.76	0	DWord(4)
Coordinate Z	0.2	4	DWord(4)
Coordinate Y	51.4	8	DWord(4)
Normal at X	127	12	Byte(1)
Normal at Z	255	13	Byte(1)
Normal at Y	127	14	Byte(1)
Light factor(?)	1	15	Byte(1)
Tangent at X	127	16	Byte(1)
Tangent at Z	255	17	Byte(1)
Tangent at Y	255	18	Byte(1)
Texture corrector X coordinate	0	19	Byte(1)
Bi-Tangent at X	0	20	Byte(1)
Bi-Tangent at Z	127	21	Byte(1)
Bi-Tangent at Y	127	22	Byte(1)
Texture corrector Y coordinate	0	23	Byte(1)
Texture coordinate X	3.1802	24	Single(4)
Texture coordinate Y	2.2143	28	Single(4)
Lightmap coordinate X	0.4023	32	ShortSingle(2)
Lightmap coordinate Y	0.000097	34	ShortSingle(2)

Indexes description

	Value	Size
Block code	10	Word(2)
Data compression (0 - no, 32768 - yes)		Word(2)
Block size (bytes)	-	DWord(4)
Number of index description blocks	-	DWord(4)
Index description block	-	-

Index description block

	Value	Size
Number of indexes in a block	-	DWord(4)
Indexes	-	DWord(4)

Index: Word(2) The number of indexes must always be a multiple of three, because triangles are constructed using indexes.

Synchronization description

(what they synchronize is still a mystery to scientists)

	Value	Size
Block code	11	Word(2)
Data compression (0 - no, 32768 - yes)	0	Word(2)
Block size (bytes)	-	DWord(4)
Number of synchronization units	-	DWord(4)
Synchronization units	-	-

Synchronization block

	Value	Size
???	0	DWord(4)
???	0	DWord(4)
???	0	DWord(4)
???	0	DWord(4)
Number of synchronization units	-	DWord(4)
Synchronization units	-	-

Synchronization unit

	Value	Size
???		DWord(4)
???		Word(2)
???		Word(2)

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Sources

Source (Wayback Machine)