MREA (Metroid Prime)
See MREA (File Format) for the other revisions of this format.
The MREA format defines areas (rooms) in Metroid Prime. It's a massive format that contains tons of different data, including terrain geometry, collision, objects, lights, and more.
|To do: |
There's a LOT of sections that are mostly known, but need some documentation written up. SCLY and collision need separate articles (although the unique parts of the collision format, like the octree, could maybe be documented here). The rest should probably stay on this page.
|This file format is almost completely documented |
Discounting unknowns within the actual data sections, the main thing that still isn't known is what the unknown data section is for.
Like CMDL, MREA files are split up into a number of 32-byte aligned sections. Every section both starts and ends on a 32-byte boundary. These are used to separate different parts of the file; different types of sections typically indicate different sets of data. The header declares the section count and the size of each one; using these is the only way to navigate the file.
These are the sections that appear in each MREA file, in the order they appear in the file:
|0x4||u32||1||Version||See hub article for a list of possible version numbers.|
|0x8||float||12||Area Transform||Matrix that represents the area's transform from the origin. Most area data is pre-transformed, so this matrix is only used occasionally.|
|0x38||u32||1||World Model Count||Number of world models in this area.|
|0x3C||u32||1||Data Section Count||Number of data sections in the file.|
|0x40||u32||1||World Geometry Section||Section index for world geometry data. Always 0; starts on materials.|
|0x44||u32||1||Script Layers Section||Section index for script layer data.|
|0x48||u32||1||Collision Section||Section index for collision data.|
|0x4C||u32||1||Unknown Section||Section index for unknown data.|
|0x50||u32||1||Lights Section||Section index for light data.|
|0x54||u32||1||Visibility Tree Section||Section index for visibility tree data.|
|0x58||u32||1||Path Section||Section index for path data.|
|0x5C||u32||1||Area Octree Section||Section index for area octree data.|
|0x60||u32||Data Section Count||Data Section Sizes||Array containing the size of each data section in the file. Every size is always a multiple of 32.|
|End of header; pad to 32 bytes before first data section begins|
MREA files have one material section, followed by a number of world models, each of which has its own set of geometry sections. There's couple small differences you'll usually see on world models compared to regular CMDL ones:
- Normals are always shorts, so vertex format 0 is never used.
- Most world models use lightmaps, so normally the first UV coordinate on each vertex will read from the short UV array. This isn't always the case, though; you need to make sure you check the material so you know where to read from.
- Surfaces will usually have a bounding box in the extra data in the surface header. This bounding box is used for depth sorting.
- Each world model starts with an extra header section which is formatted like this:
|0x0||Visor Flags||1||Visor Flags||32-bit bitfield that sets parameters controlling how the mesh renders in different visors.|
|0x4||float||12||World Model Transform||World model's transform from the area's local origin. The geometry data is pre-transformed, so this matrix can largely be ignored.|
|0x34||float||6||World Model Bounding Box||Pre-transformed axis-aligned bounding box for this model.|
|0x4C||End of mesh header section|
|1||0x2||Disable rendering in Combat/Scan Visor|
|2||0x4||Disable rendering in Thermal Visor|
|3||0x8||Disable rendering in X-Ray Visor|
|4-5||0x30||Thermal heat level.
Main article: AROT (MREA Section)
The AROT section stores the area's octree, accelerating back-to-front rendering of contained meshes. It is also used for spacial queries such as collision.
|To do: |
Format known, needs documentation written up.
The SCLY section contains data for objects.
Main article: Area Collision (File Format)
This one is sandwiched between collision and lights, and usually just contains a single 32-bit "1". Purpose is unknown. In the Prime 3/DKCR MREA format, this section is labelled
This section is for dynamic lights. See the Light article for details.
Main article: VISI (MREA Section)
This section is a PVS octree labeled "VISI". Some areas don't have visibility octrees; in that case this section will be completely empty and listed with a size of 0.
This is the final section in the file; its only value is a single PATH file ID.
|0x0||Asset ID||Area PATH Resource|
|0x4||End of section|