FTEX (File Format)

The FTEX (caFe TEXture) texture format is a format for textures which appears as a subfile of a BFRES file. It appears in the 1:st index group in a BFRES file. Unless otherwise noted, all offsets in the file are relative to themselves.

Header (FTEX)

An FTEX file begins with an 0xC0 byte header that starts with the file identifier, followed by info about the texture and mipmaps.

Offset	Size	Type	Description
0x00	4	Char[4]	File magic. Always FTEX in ASCII.
0x04	4	UInt32	Dimension. Maps to GX2SurfaceDim (line 849 here). Indicates the "shape" of a given surface or texture.
0x08	4	UInt32	Texture width. Width of the texture in pixels.
0x0C	4	UInt32	Texture height. Height of the texture in pixels.
0x10	4	UInt32	Texture depth.
0x14	4	UInt32	Number of mipmaps.
0x18	4	UInt32	Texture format. Maps to GX2SurfaceFormat (line 589 here for explanation and format values).
0x1C	4	UInt32	AA mode. Maps to GX2AAMode (line 865 here). Indicates the AA mode (number of samples) for the surface.
0x20	4	UInt32	Usage. Maps to GX2SurfaceUse (line 823 here). Indicates how the given surface may be used.
0x24	4	UInt32	Data length. Length of texture data in bytes.
0x28	4	UInt32	Data pointer. Set at runtime.
0x2C	4	UInt32	Mipmaps data length. Length of mipmaps data in bytes.
0x30	4	UInt32	Mipmaps pointer. Set at runtime.
0x34	4	UInt32	Tile mode. Maps to GX2TileMode (line 795 here). Indicates the desired tiling mode for the surface.
0x38	4	UInt32	Swizzle value.
0x3C	4	UInt32	Alignment. Always 512 * bytes per pixel.
0x40	4	UInt32	Pitch.
0x44	0x34	UInt32[13]	Mipmap offsets. An array of 13 offsets for each mipmap, relative to the start of the mipmap data.
0x78	4	UInt32	First mipmap.
0x7C	4	UInt32	Number of mipmaps (again).
0x80	4	UInt32	First slice. Always 0.
0x84	4	UInt32	Number of slices. Always 1.
0x88	4	Byte[4]	Component Selector, determines which texture color channels are used for each target channel. The bytes map to the Red, Green, Blue and Alpha channel and can receive one of the following channels. Value Name Description 0 R The channel will receive the red values of the texture. 1 G The channel will receive the green values of the texture. 2 B The channel will receive the blue values of the texture. 3 A The channel will receive the alpha values of the texture. 4 0 The channel will always have a value 0. 5 1 The channel will always have a value 1.
0x8C	0x14	UInt32[5]	Texture registers. Array of 5 unsigned integers with unknown purpose.
0xA0	4	UInt32	Texture handle. Set at runtime.
0xA4	4	UInt32	Array length (seems to be just a byte in MK8 files, with the remaining 3 bytes being padding?).
0xA8	4	Int32	File name offset.
0xAC	4	Int32	File path offset, the path of the file this data was originally created from. Stripped in Mario Kart 8 files, always pointing to an empty string at the end of the BFRES string table.
0xB0	4	Int32	Data offset. Offset to the texture data.
0xB4	4	Int32	Mipmap offset. Offset to the mipmap texture data.
0xB8	4	Int32	User Data Index Group offset.
0xBC	2	UInt16	User Data entry count.
0xBE	2	—	Padding.
0xC0	End of FTEX header

Image Data

The image and mipmap data is not present after the header. It comes after the BFRES string table instead. This seems to be a caching optimization, since the CPU generally doesn't need to handle the image data. Instead it is sent directly to the GPU.