DO/BTB

From Dark Omen Wiki

Revision as of 16:03, 7 October 2008

Building Blocks

The BTB file consists of chunks of the form:

struct CHUNK_HEADER
{
  unsigned int chunkType;
  unsigned int chunkSize; // excluding header
};

Each chunk consists of 'records' which are similar to chunks, but the record size is inclusive of the header.

struct RECORD_HEADER
{
  unsigned int recordType;
  unsigned int recordSize; // including header
};

When coordinates are referenced in the BTB file, divide them by eight to get into the same coordinates as the terrain mesh.

Overall File Structure

The observed format of the BTB files in Dark Omen follows in order:

START/END CHUNK, type=0xBEAFEED0, size=0

HEADER CHUNK, type=0, size=240
UNKNOWN CHUNK, type=1, size=<varies>
OBSTACLES CHUNK, type=2, size=<varies>
   
REGION CHUNK 0, type=3, size=<varies>
REGION CHUNK 1, type=3, size=<varies>
.
.
.
REGION CHUNK n, type=3, size=<varies>
   
GAME OBJECT CHUNK, type=4, size=<varies>

START/END CHUNK, type=0xBEAFEED0, size=0

Chunk Descriptions

Start/End Chunk

This chunk is just a marker of the start/end of the file; it contains no data

Header Chunk

HEADER CHUNK, type=0, size=240
   INTEGER RECORD (Map width) type=1, size=12
   INTEGER RECORD (Map height) type=2, size=12
   STRING RECORD (Mercenary Army file name without extension) type=1001, size=40
   STRING RECORD (Enemy Army file name without extension) type=1002, size=40
   STRING RECORD (CTL filename without extension) type=1003, size=40
   STRING RECORD ("/0") type=1004, size=40
   STRING RECORD ("/0") type=1005, size=40
   2-TUPLE RECORD ( [Number of Regions in file, Number of line segments in all regions] ) type=9, size=16

Unknown Chunk

This chunk is made up of several 3-tuples, which contain unknown data

UNKNOWN CHUNK, type=2, size=<varies>
   3-TUPLE RECORD 0 (unknown) type=3, size=20
   3-TUPLE RECORD 1 (unknown) type=3, size=20 
   .
   .
   .
   3-TUPLE RECORD n (unknown) type=3, size=20

Items for record type 3

Item type	Description	Subvalue 1	Subvalue 2
3	Defines Critical Unit Lose Condition	Unique unit ID of critical unit	Unknown
	ex (3, 1, 0) states that Morgan Bernhardt (unit id 1) must not die.

I'm not certain how to interpret this, is the "3" the same as the record type? Or is is a separate value in the record? What I mean is, this what we will see?:

CHUNK (type = 2)
  RECORD (type = 3, size = 20)
    ITEM (3, 1, 0)

Taken together, the five values in RECORD and CHUNK would together add up to 20 bytes (5x4 bytes). It is confusing since both the record and item types seem to be "3". Mikademus 16:03, 7 October 2008 (UTC)

Obstacles Chunk

This chunk seems to contain information about obstacles on the map (e.g. trees)

OBSTACLES CHUNK, type=3, size=<varies>
   INTEGER RECORD (unknown) type=8, size=12

   COMPOUND RECORD 0 (contains sub-records) type=501, size=80
      INTEGER RECORD (type of obstacle - might be bit flags - see table below) type=5, size=12
      INTEGER RECORD (x position) type=1, size=12
      INTEGER RECORD (y position) type=2, size=12
      INTEGER RECORD (unknown) type=4, size=12
      INTEGER RECORD (radius of area) type=6, size=12
      INTEGER RECORD (unknown - normally 0) type=7, size=12
   COMPOUND RECORD 1 (contains sub-records) type=501, size=80
   .
   .
   .
   COMPOUND RECORD n (contains sub-records) type=501, size=80

Type	Description
3	This obstacle blocks movement into its area
5	This obstacle blocks movement and projectiles into its area

Region Chunk

This chunk contains information which delimits an area or path. It primarily consists of a list of line segments which define the path or polygon. These areas and paths seem to be used for a variety of reasons, some of which are listed below.

REGION CHUNK, type=4, size=<varies>
   STRING RECORD (the human-readable name of the region) type=1006, size=40
   INTEGER RECORD (type code - might be bit flags - see table below) type=5, size=12
   2-TUPLE RECORD ([starting X position, starting Y position]) type=10, size=16
   4-TUPLE RECORD 0 ([ line start X, line start Y, line end X, line end Y]) type=502, size=24
   4-TUPLE RECORD 1 ([ line start X, line start Y, line end X, line end Y]) type=502, size=24
   .
   .
   .
   4-TUPLE RECORD n ([ line start X, line start Y, line end X, line end Y]) type=502, size=24

Bit	Value	Description
0	1	Always seems to be set
1	2	Closed areas have this bit set
2	4	Paths have this bit set
3	8	Unknown at this time
4	16	About half of the movement boundaries have this bit set
5	32	The Battle Region has this bit set
6	64	Unknown at this time
7	128	The other half of the movement boundaries have this bit set
8	256	Player 1 deployment area has this bit set
9	512	Player 2 deployment area has this bit set
10	1024	The Visible Region has this bit set

Game Objects Chunk

This chunk seems to hold a lot of the game-related info, for example initial enemy deployment, triggers for mission events, movement targets for the enemy AI.

GAME OBJECTS CHUNK, type=5, size=<varies>
   INTEGER RECORD (the number of game object compound records in this chunk) type=8, size=12

   COMPOUND RECORD 0 (contains sub-records and represents a game object) type=503, size=104
      INTEGER RECORD (type of game object - might be bit flags - see table below) type=5, size=12
      INTEGER RECORD (x position) type=1, size=12
      INTEGER RECORD (y position) type=2, size=12
      INTEGER RECORD (radius of area) type=6, size=12
      INTEGER RECORD (unknown) type=7, size=12
      INTEGER RECORD (unknown) type=11, size=12
      INTEGER RECORD (Unit ID) type=12, size=12
      INTEGER RECORD (unknown) type=13, size=12
   COMPOUND RECORD 1 (contains sub-records and represents a game object) type=503, size=104
   .
   .
   .
   COMPOUND RECORD n (contains sub-records and represents a game object) type=503, size=104