FF7/WorldMap Module

Preamble

The following was originaly described by Tonberry, in qhimm's forum. It was completed by Ficedula sometimes later, who reversed texture data.

Additions in italics by Aali

Two formats

BOT and MAP files are similar; BOT files are redundant and look like optimized versions of the corresponding MAP files.

MAP file follows the structure described below and is used to load single blocks on demand. BOT file also contains the same blocks but arranged to speed up initial load time by storing each block and 3 of its neighboring blocks together. For instance, the data stored for the first 2 blocks is (numbers refer to the MAP layout below): 0,1,9,10 1,2,10,11. This pattern repeats up to block #62. Replacement blocks 63-68 are divided in groups for each replacement, i.e. block 64 and 65 are part of the same group since they both belong to the Ultima Weapon crater. These groups are then stored using the same algorithm as above, each 4-block group containing a replaced block is written out again. 1-block replacements thus add 4*4 blocks to the .BOT file while 2-block replacements add 6*4 blocks. Replacements are to be made in order, when writing the data for the Ultima Weapon crater the Temple of the Ancients should be gone and so on. All of this adds up to 63*4 + 4*4 + 6*4 + 4*4 + 6*4 = 332 blocks.

Content

• WM0 is the above water map.
• WM2 is the underwater (submarine) map.
• WM3 is the snowstorm map.

MAP Format

File Structure

A worldmap file is divided in sections of 0xB800 bytes, each section representing a square block of the map.

Map Block

Each block consists in 16 meshes, organized in a grid-like fashion:

Map Block mesh arrangement

0	1	2	3
4	5	6	7
8	9	10	11
12	13	14	15

A block is recorded following the structure (all pointers are expressed in bytes relative to offset 0 of block):

Pointers have to be aligned to 4-byte boundaries, FF7 ignores the last two bits when reading the file.

For each m in 16 meshes:

size	description
4 bytes	Pointer to compressed data for mesh m

Followed by, for each m in 16 meshes:

size	description
variable	Compressed data for mesh m

The data for each mesh is independently compressed using LZSS, so the first 4 bytes are the size in bytes of the compressed data and the rest is the compressed data itself.

WM0.MAP

wm0.map contains 68 blocks. The first 63 of them are arranged in a grid-like fashion, made of 7 rows of 9 columns, like this:

wm0.map block arrangement

0	1	2	3	4	5	6	7	8
9	10	11	12	13	14	15	16	17
18	19	20	21	22	23	24	25	26
27	28	29	30	31	32	33	34	35
36	37	38	39	40	41	42	43	44
45	46	47	48	49	50	51	52	53
54	55	56	57	58	59	60	61	62

The last 5 meshes 63, 64, 65, 66, 67 and 68 replaces meshes 50, 41, 42, 60, 47 and 48 (respectively), according to the story of the game.

Mesh Structure

A worldmap mesh is recorded like this:

Header

Header Structure

size	description
2 bytes	Number of triangles
2 bytes	Number of vertices

typedef struct
{
  uint16 NumberOfTriangles;
  uint16 NumberOfVertices;
} WorldMeshHeader;

Triangle

For each triangle t in number of triangles

size	description
1 byte	Index of vertex 0 of triangle t
1 byte	Index of vertex 1 of triangle t
1 byte	Index of vertex 2 of triangle t
5 bits	Walkmap status of triangle t (see below)
3 bits	Unknown, probably script related
1 byte	Coordinate u in texture for vertex 0
1 byte	Coordinate v in texture for vertex 0
1 byte	Coordinate u in texture for vertex 1
1 byte	Coordinate v in texture for vertex 1
1 byte	Coordinate u in texture for vertex 2
1 byte	Coordinate v in texture for vertex 2
9 bits	Texture (see below)
7 bits	Location (message ID that will be displayed in the menu and savegames)

typedef struct
{
 uint8 Vertex0Index;
 uint8 Vertex1Index;
 uint8 Vertex2Index;
 uint8 WalkabilityInfo:5;
 uint8 Unknown:3;
 uint8 uVertex0, vVertex0;
 uint8 uVertex1, vVertex1;
 uint8 uVertex2, vVertex2;
 uint16 TextureInfo:9;
 uint16 Location:7;
} WorldMeshTriangle;

Vertex

For each vertex v in number of vertices

size	description
2 bytes	Coordinate x of vertex v (signed)
2 bytes	Coordinate y of vertex v (signed)
2 bytes	Coordinate z of vertex v (signed)
2 bytes	(Unknown: Coordinate w of vertex v?) Never used for anything in the PC version.

typedef struct
{
  int16 X, Y, Z;
  uint16 Unused; // fill to fit structure to 32bit boundry
} VertexType;

Normal

For each vertex v in number of vertices

size	description
2 bytes	Coordinate x of normal for vertex v
2 bytes	Coordinate y of normal for vertex v
2 bytes	Coordinate z of normal for vertex v
2 bytes	(Unknown: Coordinate w of normal for vertex v? "Always 0") Never used for anything in the PC version.

typedef struct
{
  int16 X, Y, Z;
  uint16 Unused; // fill to fit structure to 32bit boundry
} NormalType;

structures added by Cyberman 13:43, 10 Jan 2007 (CST)

Walkmap

code	description
0x23	Deep sea (can't land highwind, water spray when flying low)
0x22	No sea spray from highwind, can't land
0x21	No sea spray from highwind, can't land
0x20	No sea spray, can land and walk

Observe that 0x21 and 0x22 describe the same status; it is thought that it may differentiate chocobos' behavior.

Texture

The lower 9 bits contain a texture number (0-511, but only 0-281 appear to be used). The text files in the Reeve download show how each number maps to one (or more) .TEX files within WORLD_US.LGP (see also LGP Archives). The upper bits have something to do with texture coordinate mapping.

BOT format

(FIXME)