Geometry (Donkey Kong Country Returns)

The format for geometry in Donkey Kong Country Returns appears in the CMDL and MREA formats.

Geometry

An important thing to note off the bat is that both CMDL and MREA files are split up into a number of 32-byte-aligned sections; their respective headers both declare a section count, and list the sizes of each section contained in the file. This is required to navigate to different parts of the file, and is required in order to read the geometry data correctly. Sections are generally split based on the type of data contained in them, so one section might contain vertex coordinates, while another contains a surface (submesh) definition. For the purposes of this article, each subheader will mark the start of a new section; use that as your cue to advance to the next one. Check the CMDL or MREA pages for more info on how the sections work.

All data sections appear in the order that they're listed on this page.

For vertex attributes, note that there's no count value present anywhere. If you want a rough count, you can divide the size of that attribute's section by the attribute's size; this approach doesn't account for padding, however.

Vertex Coordinates

Vertex coords can be stored as either floats or signed shorts, depending whether flag 0x20 is set in the header. If they're shorts, then they need to be divided by 0x2000 to get the corresponding float value. Since they're signed numbers, that means that 0 to 0x7FFF correspond to the range 0.0-4.0, and 0x8000 to 0xFFFF correspond to the range -4.0-0.0.

Normals

Vertex normals are usually stored as shorts. To get the corresponding float value, read as a signed short and divide by 0x4000.

Vertex Color

Normally unused, so this section is typically empty and zeroed out.

Float UV Coordinates

These are stored as a sequence of two floats.

Short UV Coordinates

Like the short vertex coordinates, these are stored as signed shorts that should be divided by 0x2000 to get the corresponding float value. The short UVs section has received a fairly significant increase in usage in DKCR compared to the Prime series; in the Prime games, they were generally only used for lightmaps, whereas in DKCR they're often used by pretty much anything.

Surface Definitions

This section is very small and simple; it simply declares a surface count and then lists the offsets to the end of each surface. Following this section, there'll be one additional section per surface.

Type	Count	Name	Notes
u32	1	Surface Count
u32	Surface Count	Surface Offsets	Relative to the start of the first surface.
Surface sections begin

Surface

There will be one of these sections per surface. Each surface starts with a small 32-byte header; after that, the primitive data begins.

Offset	Type	Count	Name	Notes
0x0	float	3	Center Point	Unknown purpose
0xC	u16	1	Mantissa	Always 0x8000
0xE	u16	1	Primitive Table Size	This value is not reliable in the Metroid Prime series, so you probably shouldn't rely on it in DKCR either.
0x10	u32	1	Unknown	Always 0?}}
0x14	u32	1	Unknown	Always 0?
0x18	u16	1	Unknown	Value varies, but is sometimes 0xFFFF
0x1A	u16	1	Material Index
0x1C	u8	1	Unknown	Always 0xFF?
0x1D	u8	1	Visibility Group Index
0x1E	u16	1	UV Array Index	If 0, this surface uses the float UVs array; if 1, this surface uses the short UVs array
0x20	End of surface header; primitive data starts

The primitive data is a standard GX display list. Each primitive begins with a byte that contains the primitive type in the upper 5 bits, and the vertex format setting in the lower 3. After that is a 16-bit vertex count, followed by a series of 16-bit vertex attribute indices.

You'll need to check some settings on the material to read the primitive data properly; the material determines which vertex attributes are present.

There is no primitive count value; you'll need to continue reading data until you hit the end of the primitive table. There are a couple values you can use for reference; either the surface section size, or the surface's end offset. It's not recommended to use the primitive table size value because that value has been shown to be inaccurate in some cases in the Prime series and this may be the case in DKCR as well.

There are 7 primitive types supported by GX, indicated in the upper 5 bits of the flag value. Note that the game only ever actually uses triangles, triangle strips, and triangle fans; however, all of these primitives are supported by GX and are therefore supported by the game, and so they could be used in custom model files.

Value	Primitive
0x80	Quads
0x90	Triangles
0x98	Triangle Strip
0xA0	Triangle Fan
0xA8	Lines
0xB0	Line Strip
0xB8	Points