BMB (Binary Model Blob) format

A BMB file is a model composed by a collection of vertex positions, vertex normals, texture coordinates (UV) and faces. BMB currently supports only one mesh per file.

Since the target platform runs on PowerPC, assume all values are big-endian.

Just like OBJ (original format), position, normals and coordinates are uncoupled and can be reused more than once.

Notes

Due to how the physics in rehover is handled, the faces must be specified with a specific order: All faces with a normal between -0.01 and 0.01 must be placed after all the other ones

Limits

Field	Limit
Unique vertex positions	x < 65536
Unique vertex normals	x < 65536
Unique texture coordinates	x < 65536
Total faces	x < 65536

File format

Name	Data type	Length (bytes)
Header	BMB header	8
Vertex positions	vertex position array	12 * # of vertex positions
Vertex normals	vertex normal array	12 * # of vertex normals
Texture coordinates	texture coordinate array	8 * # of texture coords
Floor Faces	face data array	18 * # of floor faces
Wall Faces	face data array	18 * # of wall faces

Header format

Offset	Name	Data type	Length (bytes)
0x0	# of vertex positions	uint16	2
0x2	# of vertex normals	uint16	2
0x4	# of texture coordinates	uint16	2
0x6	# of faces	uint16	2

Vertex position/normal format

Offset	Name	Data type	Length (bytes)
0x0	X	float32	4
0x4	Y	float32	4
0x8	Z	float32	4

Texture coordinate format

Offset	Name	Data type	Length (bytes)
0x0	U	float32	4
0x4	V	float32	4

Face format

Each face is made of 3 vertices forming a triangle:

Face data

Offset	Name	Data type	Length (bytes)
0x0	Vertex 1	vertex data (see below)	6
0x6	Vertex 2	vertex data (see below)	6
0xC	Vertex 3	vertex data (see below)	6

Vertex data

Offset	Name	Data type	Length (bytes)
0x0	Vertex position index	uint16	2
0x2	Texture coordinate index	uint16	2
0x4	Vertex normal index	uint16	2