COL (File Format)

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COL is a collision format used in Mario Kart Arcade GP DX.

File Format

The file byte order is always little endian.

Header

The file starts with the following header:

Offset	Type	Description
0x00	Char[4]	File magic. Always COL\0 in ASCII.
0x04	Byte[4]	Timestamp? Always 16 08 12 20 (2012-08-16?) The game specifically checks if this value is correct, otherwise it won't read the file.
0x08	Int32	Grid width (W).
0x0C	Int32	Grid length (L).
0x10	Float	Grid cell X size.
0x14	Float	Grid cell Y size.
0x18	Float[3]	AABB minimum coordinate.
0x24	Float[3]	AABB maximal coordinate.

Grid

Followed by the header, the grid data is read from the start of the AABB minimum coordinate, from left to right. A total of W * L cells are loaded.

Cell

Offset	Type	Description
0x00	Int32	Number of Triangles (T).
0x04	Int32	Number of Cubes (C).

Triangle

Followed by the cell header, there are T 0x70 triangles.

Offset	Type	Description
0x00	Float[4]	Unknown.
0x10	Float[3][3]	Triangle vertices XYZ position.
0x34	Float[3][3]	Unknown. Perhaps triangle normals or some kind of direction XYZ position?
0x58	Int32	Unknown. Maybe determines which edges of the triangle are surrounded by walls?
0x5C	UInt32	COL flag.
0x60	Float[4]	Unknown.

Cube

Followed by the cell's triangles, there are C 0x40 cubes, perhaps used for wall collision.

Offset	Type	Description
0x00	Float[4][4]	Unknown.

Secondary Grid

Followed by the grid, there's a secondary grid with unknown blocks. As of version 1.18 of Mario Kart Arcade GP DX, it only seems to be used in FM_L_N_HIT.col and FM_L_N_HIT_cam.col.

Cell

Offset	Type	Description
0x00	Int32	Number of Unknown sections (U).

Unknown Section

Followed by the cell header, there are U 0x38 unknown sections.

Offset	Type	Description
0x00	Int32	Unknown.
0x04	Float[3][3]	Unknown.
0x28	Float[4]	Unknown. Always 0.

Tools

The following tools can handle COL files:

• (none)