CMDL (Tropical Freeze)

See CMDL (File Format) for the other revisions of this format.

The CMDL, SMDL, and WMDL format are Tropical Freeze's three model formats; CMDL is a generic model format, SMDL is for skinned models, and WMDL is for world (terrain) models. All three are the same basic format, with SMDL and WMDL each containing an extra data section at the start of the file. With the Wii U's graphics system being updated from GX to GX2, the Retro model format has been dramatically overhauled, bearing little to no resemblance to the previous CMDL format found in DKCR and the Prime series.

This file format needs more research There's still a lot of unknown data. The entire optional section at the end of HEAD is completely unknown to me and there's lots of scattered unknown values.

Format

After the RFRM Header, the first section of the file is SKHD in SMDL, and WDHD in WMDL. Following those extra sections, all three formats start with a header.

HEAD

Offset	Size	Description
0x0	24	"HEAD" section header
0x18	4	Unknown
0x1C	4	Unknown
0x20	4	Unknown
0x24	4	Unknown
0x28	4	Unknown
0x2C	24	Axis-aligned bounding box
0x30	4	Extra data flag

If the ending flag is 1, then a large chunk of extra data follows before the next section begins; otherwise, the HEAD section ends.

MTRL

The MTRL section has a 32-bit material count, then lays out its materials one after the other. The material structure is somewhat complicated; each material has a name, something that wasn't present in Retro's previous material formats, as well as a shader ID. The rest of the material structure appears to be defining parameters to pass to the shader. This needs a lot more research to determine what the parameters are and what the different data is.

Type	Size	Description
string	-	Name (zero-terminated)
MTRL	16	Shader ID
char[4]	4	Shading type fourCC; can be PHNG, LAMB, SURF, or FURM
u32	4	Unknown
u32	4	Subsection count

Material subsections each have a fourCC name and a type identifer, followed by a set of parameters. The type and number of parameters is dependent on the subsection type; there are five known types currently.

Offset	Type	Size	Description
0x0	char[4]	4	Section name fourCC
0x4	u32	4	Section type
0x8	struct	-	Section data struct; type varies based on the section type value
End of subsection; next one begins

Type 0: Texture Map

Offset	Type	Size	Description
0x0	TXTR	0x10	Texture ID
0x10	u32	4	Unknown
0x14	u32	4	Unknown
0x18	u32	4	Unknown
0x1C	u32	4	Unknown
0x20	u32	4	Unknown
0x24	End of struct

Type 1: Unknown

Offset	Type	Size	Description
0x0	float	4	Unknown
0x4	float	4	Unknown
0x8	float	4	Unknown
0xC	float	4	Unknown
0x10	End of struct

Type 2: Unknown

Offset	Type	Size	Description
0x0	float	4	Unknown
0x4	End of struct

Type 4: Unknown

Offset	Type	Size	Description
0x0	u32	4	Unknown
0x4	float	4	Unknown
0x8	float	4	Unknown
0xC	float	4	Unknown
0x10	float	4	Unknown
0x14	float	4	Unknown
0x18	float	4	Unknown
0x1C	float	4	Unknown
0x20	u32	4	Unknown
0x24	u32	4	Unknown
0x28	u32	4	Unknown
0x2C	u32	4	Unknown
0x30	u32	4	Unknown
0x34	u8	1	Unknown
0x35	TXTR	0x10	Unknown Texture ID
0x45	u32	4	Unknown
0x49	u32	4	Unknown
0x4D	u32	4	Unknown
0x51	u32	4	Unknown
0x55	u32	4	Unknown
0x59	TXTR	0x10	Unknown Texture ID
0x69	u32	4	Unknown
0x6D	u32	4	Unknown
0x71	u32	4	Unknown
0x75	u32	4	Unknown
0x79	u32	4	Unknown
0x7D	u32	4	Unknown
0x81	u32	4	Unknown
0x85	u32	4	Unknown
0x89	u32	4	Unknown
0x8D	End of struct

Type 5: Unknown

Offset	Type	Size	Description
0x0	u32	4	Unknown
0x4	u32	4	Unknown
0x8	u32	4	Unknown
0xC	u32	4	Unknown
0x10	End of struct

MESH

The MESH section does what the name suggests: it defines submeshes. The MESH section header is as follows:

Offset	Size	Description
0x0	24	"HEAD" section header
0x18	4	Submesh count
0x1C	End of MESH header

Each submesh definition is structured as follows:

Offset	Size	Description
0x0	4	Unknown; always 3?
0x4	2	Material ID
0x6	1	Vertex buffer ID
0x7	1	Index buffer ID
0x8	4	Start index
0xC	4	Index count
0x10	4	Unknown
0x14	1	Unknown; usually seems to be either 0 or 1, possibly a bool value
0x15	End of submesh definition

VBUF

The VBUF section defines vertex buffers; each buffer can have different vertex types, with different strides and attributes.

Header

Offset	Size	Description
0x0	24	"VBUF" section header
0x18	4	Vertex buffer count
0x1C	End of VBUF header

Vertex Buffer

Offset	Size	Description
0x0	4	Vertex count
0x4	4	Attrib count (AC)
0x8	0x14 × AC	Vertex attributes
End of vertex buffer

Vertex Attribute

Offset	Size	Description
0x0	4	Unknown
0x4	4	Offset
0x8	4	Stride
0xC	4	Unknown
0x10	4	Unknown (likely attrib type/format)
0x14	End of attribute

IBUF

Just like how the VBUF section defines vertex buffers, the IBUF section defines index buffers. Each index buffer only has one value associated with it, so it's fairly simple, and you generally will only see one or two index buffers per file.

Header

Offset	Size	Description
0x0	24	"IBUF" section header
0x18	4	Index buffer count
0x1C	End of IBUF header

Index Buffer

Offset	Size	Description
0x0	4	Format (1 means unsigned short; 2 means unsigned long)
0x4	End of index buffer

GPU

The GPU section contains raw buffer data that's fed to the GPU. It's essentially just a giant blob with all the vertex and index buffers laid out next to each other. The tricky part is, all the buffer data is LZSS-compressed, and the metadata needed to decompress it is stored in the pak rather than in the files themselves; not only that, but that metadata is also the only way to distinguish the different buffers from each other.

As such, this section can't be read correctly if the model file is unpacked and completely left as-is; it needs to be either read directly from the pak, or the metadata needs to be added to the file in some way. A good unpacker should append the metadata to the end of the file; a pre-decompressed file needs the buffer sizes or offsets inserted into the file data somewhere.

PAK Metadata

The pak metadata for the model formats contains mainly information related to the size and layout of the GPU section, and the metadata required to locate and decompress specific buffers within it.

Offset	Size	Description
0x0	4	Unknown; always 4?
0x4	4	GPU section offset
0x8	4	GPU chunk count (CC)
0xC	8 × CC	GPU chunk definitions
-	4	Compressed vertex buffer count (VC)
-	0x10 × VC	Vertex buffer definitions
-	4	Compressed index buffer count (IC)
-	0x10 × IC	Index buffer definitions
End of pak metadata

GPU Chunk

For large models, the GPU section might be split up into multiple chunks, rather than read as one data buffer; all offsets into the GPU section will be relative to the start of the chosen chunk.

Offset	Size	Description
0x0	4	Size
0x4	4	Offset
0x8	End of GPU chunk definition

Compressed Buffer

The format for compressed buffer definitions is the same regardless of buffer type (vertex/index).

Offset	Size	Description
0x0	4	GPU chunk index
0x4	4	Start offset (relative to the start of the chosen GPU chunk)
0x8	4	Compressed size
0xC	4	Decompressed size
0x10	End of compressed buffer definition