BFG (File Format)

BFG (Binary FoG) files are one of the multiple post-effect controllers Mario Kart Wii provides. It controls fog used in tracks, and they appear in the "./posteffect" folder inside U8 files.

File Format

The structure of the file is based in four fog entries, 0x1C (28) bytes long each.

Table showing fog types, with their curve equations

Offset	Type	Description
0x00	Int32	Fog type: 0x0 = No fog. 0x1 = Perspective projection linear. 0x2 = Perspective projection exponential. 0x3 = Perspective projection exponent squared. 0x4 = Perspective projection inverse exponent. 0x5 = Perspective projection inverse of the square exponent. 0x6 = Ortographic projection linear. 0x7 = Ortographic projection exponential. 0x8 = Ortographic projection exponent squared. 0x9 = Ortographic projection inverse exponent. 0xA = Ortographic projection inverse of the square exponent.
0x04	Float	StartZ: stores the Z value where fog generation begins inside the view space.
0x08	Float	EndZ: stores the Z value at which fog density is maximum inside the view space.
0x0C	Byte[4]	Fog color, stored in RGBX format (alpha is ignored).
0x10	UInt16	Fog range correction: 0x0 = Disabled. 0x1 = Enabled.
0x12	UInt16	Maybe center to which the range correction is applied?
0x14	Float	Affects the transition speed when swapping fog entries. 1.0 is instant, lower values create longer fades. Whether it affects swapping to this entry, from this entry, or both is unknown.
0x18	UInt16	Unknown.
0x1A	UInt16	Unknown.
0x1C	End of fog entry

Tools

The following tools can handle BFG files:

• FogConv, by Atlas
• Post-Effect Editor, by Wexos