CGFX

From 3dbrew
Revision as of 19:28, 8 September 2014 by Planetarian (talk | contribs) (→‎CGFX)
Jump to navigation Jump to search

CGFX is a container format used to store graphics resources. It can contain 3D models, textures and animation data.

CGFX

CGFX header :

Offset Length Description
0x0 0x4 Magic "CGFX"
0x4 0x2 Byte order mark: FFFE (little endian) or FEFF (big endian)
0x6 0x4 CGFX header size
0xA 0x2 ?
0xC 0x4 File size (bytes)
0x10 0x4 Number of entries

A typical CGFX file contains two main entries, beginning directly after the CGFX header: DATA and IMAG.

DATA

DATA contains a list of DICT references.

DATA header (for N = 0..15) :

Offset Length Description
0x0 0x4 Magic "DATA"
0x4 0x4 DATA Size (in bytes)
0x8 +(N*8) 0x4 Number of entries in DICT N
0xC +(N*8) 0x4 Offset (self-relative) to DICT N

The DATA header contains the entry counts and offsets for each DICT entry, and holds sixteen such references. Unused references are zero-padded.

DICT

DICTs are generic structures used to store values (and associate them to a key ?). A DICT header is 0x1C bytes long.

DICT header :

Offset Length Description
0x0 0x4 Magic "DICT"
0x4 0x4 DICT size (in bytes)
0x8 0x4 Number of entries
0xC 0x10 ?

DICT entry:

Offset Length Description
0x0 0x4 ?
0x4 0x2 ?
0x6 0x2 ?
0x8 0x4 Offset (self-relative) to symbol
0xC 0x4 Value (often offsets)

CMDL

CMDL is used to describe a 3D model.

CMDL Header :

Offset Length Description
0x0 0x4 Magic "CMDL"
0x8 0x4 CMDL section size (in bytes)
0x24 0x4 Number of entries in first DICT ?
0x28 0x4 Offset (self-relative) to first DICT
0x2C 0xC Global scale vector (3 floats : x, y, z)
0xB0 0x4 N/2, where N is the number of entries in SOBJ list
0xB4 0x4 Offset (self-relative) to SOBJ list
0xBC 0x4 Offset (self-relative) to MTOB DICT
0xB4+[0xB4] 0x4*N*2 SOBJ list; each word is an offset (self-relative) to an SOBJ structure

A CMDL section refers to outside data; it can not be considered separately from the rest of the CGFX file. The second DICT in the CMDL section contains offsets to MTOB objects.

SOBJ

SOBJ structures can be used to describe 3D objects that are part of the model. If such is the case then they will follow this structure :

Offset Length Description
0x0 0x3 Flags ?
0x3 0x1 SOBJ type ? (0x10 = model, 0x02 = skeleton)
0x4 0x4 Magic "SOBJ"
0x44 0x4 Y = Offset (self-relative) to bone correspondance array
0x48 0x4 X = Offset (relative to SOBJ magic) to SOBJ data structure (wrong ?)
0x44+Y+0x00 0x4 N = Number of bone IDs in bone correspondance array
0x44+Y+0x14 0x4*N Bone correspondance array
X+0x18 0x1 Face data format (?) : 0x1 = u8, 0x3 = u16
X+0x20 0x4 Face data section size (in bytes)
X+0x24 0x4 Face data section offset (self-relative)
X+0x58 0x4 Vertex data section size (in bytes)
X+0x5C 0x4 Vertex data section offset (self-relative)
X+0x68 0x1 Vertex data format size (in bytes)
Vertex format size Description
0x14 X (float), Y (float), Z (float), U (float), V (float)
0x18 X (float), Y (float), Z (float), Unk (u32?), U (float), V (float)
0x20 X (float), Y (float), Z (float), NX (float), NY (float), NZ (float), U (float), V (float)
0x28v1 X (float), Y (float), Z (float), NX (float), NY (float), NZ (float), U (float), V (float), (local) Bone IDs (4*u8), Bone weights (4*u8)
0x28v2 X (float), Y (float), Z (float), NX (float), NY (float), NZ (float), U (float), V (float), Unk1 (u32), (local) Bone IDs (2*u8), Bone weights (2*u8)

Vertex format 0x28 (and possibly others) supports multiple bone assignment. In this case, the sum of all bone weights is 0x64.

TXOB

TXOBs are contained within MTOBs. They can describe textures; if such is the case, then their structure is as follows :

Offset Length Description
0x0 0x4 Magic "TXOB"
0x14 0x4 Texture height
0x18 0x4 Texture width
0x30 0x1 Texture format ID (see table below)
0x38 0x4 Texture height (?)
0x3C 0x4 Texture width (?)
0x40 0x4 Texture data size
0x44 0x4 Texture data offset (self-relative)
Texture format ID Description
0x0 RGBA8
0x1 RGB8
0x2 RGBA5551
0x3 RGB565
0x4 RGBA4
0x5 LA8
0x6 HILO8
0x7 L8
0x8 A8
0x9 LA4
0xA L4
0xB A4 ?
0xC ETC1 (see notes below)
0xD ETC1A4 ?

Every texture format has its texture data divided into 8x8 tiles. See SMDH for more information. ETC1 is a compressed texture format which compresses blocks of 4x4 pixels into u64s. These u64 are traditionally stored in big endian; however, nintendo's implementation stores them in little endian. ETC1 textures are stored in 8x8 tiles; decompressed 4x4 therefore have to be organized accordingly. See [1] for implementation example.

LUTS

Appears to contain color lookup tables possibly for use with shaders.

LUTS Header:

Offset Length Description
0x0 0x4 Magic "LUTS"
0x4 0x2 Seems to adhere to powers of 2 (width/height/flags?)
0x6 0x2 Seems to adhere to powers of 2 (width/height/flags?)
0x8 0x4 ?
0xC 0x8 all zeroes ?
0x14 0x4 ?
0x18 0x4 Offset to DICT (self-relative) ?

All observed instances have an otherwise unreferenced DICT section immediately afterward (the last LUTS value being a 0x4, which may describe the relative position of that DICT), which appears to describe material specularity.

Skeleton data

Skeleton data is stored in an array. Each entry is 0xE0 bytes in length and organized this way :

Offset Length Description
0x0 0x4 Offset (self relative) to name symbol
0x8 0x4 Joint ID
0xC 0x4 Parent joint ID
0x10 0x4 Signed offset (self-relative) to parent joint
0x2C 0xC Angle vector (floats, x, y, z)
0x38 0xC Position vector (floats, x, y, z)
0x44 0x30 Transformation matrix (4x3)
0x70 0x30 Identity matrix ? (4x3)

Each entry stores the joint transformation data twice; once as angle/position vectors and once as a transformation matrix. Each entry also stores a second matrix which appears to always be identity. (?)

CANM

CANMs are used to store skeletal animation data.

Links

Retrieved from "https://www.3dbrew.org/w/index.php?title=CGFX&oldid=9808"