COL (File Format)

COL is a collision format used in Mario Kart Arcade GP DX and the successor of Mario Kart Arcade GP and Mario Kart Arcade GP 2's MKAGP BIN.

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[2]	AABB minimum coordinate XZ.
0x20	Float[2]	AABB maximum coordinate XZ.
0x28	Float[2]	Negative AABB minimum coordinate XZ. Unknown usage.

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 Walls (C).

Triangle

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

Offset	Type	Description
0x00	Float[2]	Minimal coordinate for this triangle.
0x08	Float[2]	Maximal coordinate for this triangle.
0x10	Float[3][3]	Triangle vertices XYZ position.
0x34	Float[3][3]	Triangle edges XYZ directions.
0x58	UInt32	Neighbour triangle flag, used to determine which edges connect to other triangles.
0x5C	UInt32	COL flag.
0x60	Float[3]	Triangle normal.
0x6C	Float	Negative dot product between triangle center and triangle normal.

Wall

Followed by the cell's triangles, there are C 0x40 walls, which are used for wall collision detection. The walls are auto-generated from all triangles by checking which edges are missing neighbour triangles.

Offset	Type	Description
0x00	Float[3]	Min XYZ of the triangle edge.
0x0C	Float	Unknown. Always 0.
0x10	Float[3]	Max XYZ of the triangle edge.
0x1C	Float	Unknown. Always 0.
0x20	Float[3]	Position 1 XYZ of the triangle edge forming the wall.
0x2C	Float	Unknown. Always 0.
0x20	Float[3]	Position 2 XYZ of the triangle edge forming the wall.
0x3C	Float	Unknown. Always 0.

Triangle Wall Grid

Followed by the grid, there's a secondary grid with cells containing triangle walls. 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.

Triangle Wall Cell

Offset	Type	Description
0x00	Int32	Number of triangle walls (U).

Triangle Wall

Followed by the cell header, there are U 0x38 triangle walls. These are walls represented as triangles. Presumably this was added since edge walls which are auto-generated couldn't represent certain walls.

Offset	Type	Description
0x00	Int32	Unknown. Possible collision flag indicating surface type.
0x04	Float[3][3]	Triangle vertices XYZ position.
0x28	Float[4]	Unknown. Always 0.

Tools

The following tools can handle COL files:

• (none)