Terrain records

LIB/PART000.DAT

One 46-byte record per terrain tile: how units may enter it and which tile it becomes in each weather.

Status: the layout is read from the data and checked against the tile pixels and against how the game moves units and draws weather. The weather array is the best-tested part; most other words in the record are still unknown.

record 46 Brecords 1335layout array of TerrainRecord, no headerbyte order little-endianfields 12 ● 4 ◐ 2 ○ 6

Terrain46 bytes

0x000 0 0

× 1335

Point at the bar to name a field; select it to jump to its row.

knownpartly knownunknown: investigatenamed, never setalways one valueunused bits

0x00u16lereserved_head ●always 0Always 0.

0x02u16leunknown_word_02 ◐0–940841 distinct valuesNon-zero in 527 records, 41 distinct values up to 9408.

0x04u16leunknown_word_04 ○0 · 88 in exactly one record, 0 in the rest.

0x06u32leentry_mask ●Entry MaskTerrain-entry class: a bit set, one bit per tile in all but eleven records.

313029282726252423222120191817161514131211109876543210

23 named9 unused

bit	mask	name	meaning
0	0x000001	road	Road.
1	0x000002	path	Path.
2	0x000004	ditch	Ditch; also the fortification overlay `PART0093`.
3	0x000008	rail	Rail.
4	0x000010	minor obstacle	Rocks, scrub, mounds, small pipes and posts. Wheeled vehicles, ships and trains cannot enter.
5	0x000020	major obstacle	Pipelines and machinery. Only light ground vehicles and aircraft can enter.
6	0x000040	hill	Hill.
7	0x000080	mountain	Mountain.
8	0x000100	slope	Slope.
9	0x000200	grassland	Grassland.
10	0x000400	forest	Forest.
11	0x000800	hazard	Pipes, pools, spills, lava, shafts, bore holes and geysers, plus the animation placeholder tiles. Only aircraft can enter.
12	0x001000	water basin	Water basin.
13	0x002000	mud	Mud.
14	0x004000	snow	Snow-covered open ground.
15	0x008000	rock in water	Rock in water.
16	0x010000	shallow water	Shallow water.
17	0x020000	medium water	Medium water.
18	0x040000	deep water	Deep water.
19	0x080000	ice	Ice.
20	0x100000	building	Building.
21	0x200000	building (enterable)	Building a unit can enter.
22	0x400000	building entrance	Building entrance.
23–31		unused	Never set in any record.

0x0au16leunknown_word_0a ○0x0000–0x052b41 distinct valuesNon-zero in only 40 records but 41 distinct values up to 1323: index-shaped, not a flag.

0x0cu16leunknown_word_0c ○0x0000–0x03e760 distinct valuesNon-zero in 159 records, 60 distinct values up to 999.

0x0eu16leunknown_word_0e ○0 · 12 · 20Non-zero in 2 records.

0x10u16leunknown_word_10 ○0–88 distinct values8 distinct values, max 8, non-zero in 40 records.

0x12u16leunknown_word_12 ◐0–26411 distinct valuesNon-zero in 218 records, 11 distinct values up to 264.

0x14u16le[5]weathermapping ●0–13341118 distinct valuesThe sprite drawn in each of five weather states.

0x1eu16leunknown_word_1e ○0x0000 · 0x02cf · 0x02f5 · 0x03b2Non-zero in 3 records only.

0x20u8[14]reserved_tail ●always 0Zero in every shipped record.

Example: a mud tile and its weather

Terrain tile PART0131 is record 131, so its 46 bytes start at 131 x 46 = 0x178a in PART000.DAT. Each line is one field: its offset in the record, its bytes as stored, and the value they decode to.

0x00  00 00                      reserved_head = 0
0x02  10 00                      unknown_word_02 = 16
0x04  00 00                      unknown_word_04 = 0
0x06  00 20 00 00                entry_mask = 0x00002000: mud
0x0a  00 00                      unknown_word_0a = 0
0x0c  00 00                      unknown_word_0c = 0
0x0e  00 00                      unknown_word_0e = 0
0x10  00 00                      unknown_word_10 = 0
0x12  00 00                      unknown_word_12 = 0
0x14  83 00 1e 03 30 03 4f 02 be 02    weathermapping = 131, 798, 816, 591, 702
0x1e  00 00                      unknown_word_1e = 0
0x20  00 00 00 00 00 00 00 00 00 00 00 00 00 00    reserved_tail = 0

weathermapping lists the tile drawn in each of the five weather states, in order: sunny 131 (this tile itself), light rain 798, heavy rain 816, light snow 591 and heavy snow 702. The first four are mud as well (entry_mask 0x2000). The heavy snow tile 702 has entry_mask 0x4000, the snow class, so the same ground changes class when the snow arrives.

Still to investigate

Every field marked unknown or partial above, and every bit that is set without a name or named without ever being set.

unknown_word_02◐Non-zero in 527 records, 41 distinct values up to 9408. TerrainRecord
unknown_word_04○8 in exactly one record, 0 in the rest. TerrainRecord
unknown_word_0a○Non-zero in only 40 records but 41 distinct values up to 1323: index-shaped, not a flag. TerrainRecord
unknown_word_0c○Non-zero in 159 records, 60 distinct values up to 999. TerrainRecord
unknown_word_0e○Non-zero in 2 records. TerrainRecord
unknown_word_10○8 distinct values, max 8, non-zero in 40 records. TerrainRecord
unknown_word_12◐Non-zero in 218 records, 11 distinct values up to 264. TerrainRecord
unknown_word_1e○Non-zero in 3 records only. TerrainRecord

/* Terrain Records (LIB/PART000.DAT). All fields little-endian unless the type says otherwise.

* Each comment gives status (● known ◐ partial ○ unknown), values seen, and meaning. */

/* File Layout */

struct FileLayout {

/*..*/TerrainRecordterrain_records[];// ● 0x0000..endrecord_count = file_size / 46.

};

/* TerrainRecord */

struct TerrainRecord {

/*00*/uint16_treserved_head;// ● always 0Always 0.

/*02*/uint16_tunknown_word_02;// ◐ 0–9408Non-zero in 527 records, 41 distinct values up to 9408.

/*04*/uint16_tunknown_word_04;// ○ 0 · 88 in exactly one record, 0 in the rest.

/*06*/uint32_tentry_mask;// ● Entry MaskTerrain-entry class: a bit set, one bit per tile in all but eleven records.

/*0a*/uint16_tunknown_word_0a;// ○ 0x0000–0x052bNon-zero in only 40 records but 41 distinct values up to 1323: index-shaped, not a flag.

/*0c*/uint16_tunknown_word_0c;// ○ 0x0000–0x03e7Non-zero in 159 records, 60 distinct values up to 999.

/*0e*/uint16_tunknown_word_0e;// ○ 0 · 12 · 20Non-zero in 2 records.

/*10*/uint16_tunknown_word_10;// ○ 0–88 distinct values, max 8, non-zero in 40 records.

/*12*/uint16_tunknown_word_12;// ◐ 0–264Non-zero in 218 records, 11 distinct values up to 264.

/*14*/uint16_tweathermapping[5];// ● 0–1334The sprite drawn in each of five weather states.

/*1e*/uint16_tunknown_word_1e;// ○ 0x0000 · 0x02cf · 0x…Non-zero in 3 records only.

/*20*/uint8_treserved_tail[14];// ● always 0Zero in every shipped record.

}; /* 46 bytes */

/* entry_mask */

enum EntryMask : uint32_t {

EM_ROAD = 0x00000001,

EM_PATH = 0x00000002,

EM_DITCH = 0x00000004,

EM_RAIL = 0x00000008,

EM_MINOR_OBSTACLE = 0x00000010,

EM_MAJOR_OBSTACLE = 0x00000020,

EM_HILL = 0x00000040,

EM_MOUNTAIN = 0x00000080,

EM_SLOPE = 0x00000100,

EM_GRASSLAND = 0x00000200,

EM_FOREST = 0x00000400,

EM_HAZARD = 0x00000800,

EM_WATER_BASIN = 0x00001000,

EM_MUD = 0x00002000,

EM_SNOW = 0x00004000,

EM_ROCK_IN_WATER = 0x00008000,

EM_SHALLOW_WATER = 0x00010000,

EM_MEDIUM_WATER = 0x00020000,

EM_DEEP_WATER = 0x00040000,

EM_ICE = 0x00080000,

EM_BUILDING = 0x00100000,

EM_BUILDING_ENTERABLE = 0x00200000,

EM_BUILDING_ENTRANCE = 0x00400000,

/* bits 23–31: never set */

};