# OpenTTD Landscape Internals
Structure of OpenTTD (OTTD) landscape arrays
Author: Marcin Grzegorczyk

### Landscape

Seven attributes (counting "type_height") hold the informations about a tile.
These attributes are referred to as "type_height", "m1", "m2", "m3", "m4", "m5" and "m6".
The most important value is the class of a tile, stored in the upper 4 bits of the type_height attribute. The lower 4 bits are used to encode the height and slope data.

Special Attribute : m6. There are 4 bits of it that are used accross multiple tile classes

- Bits 7..6 :

  Presence and direction of bridge above, for tiles that support this.
  `00` | no bridge
  `01` | Axis X (North-East)
  `02` | Axis Y (South-West)

- Bits 1..0 :

  Only meaningfull in tropic climate. It contains the definition of the two available zones
  `00` | invalid zone
  `01` | desert
  `02` | rain forest

  In any other climate, those 2 bits are free of use.

For a graphical representation of the tile-layout have a look at Landscape grid page.

The owner of a tile, as frequently associated with attribute m1, can be either players (human or AI) or "Game entities". They are identified using:

`00` | current player
`01..08` | AI or network players
`0F` | a town owns the tile
`10` | nobody owns the tile
`11` | "water" owns the tile
`FF` | spectator in MP or in scenario editor

OTTD's class-specific periodic tile processing routine is called once every +256 ticks for each tile.

Class | Meaning & details of encoding
--- | ---
`0` | Ground

- m1: owner of the tile (normally `10`)
- m4 bits 7..5: type of hedge on the SW border of the tile (1 through 6, or 0=none)
- m4 bits 4..2: same as 7..5, but for the SE border
- m5 bits 7..5: update counter, incremented on every periodic processing for tile types, other than `03`, `07`, `0B`, `10` and above.
  on wraparound, the tile is updated (for fields, the type of fields in m3 is increased, for other types the tile type in m5 is increased).
  For snow and desert, these bits are not used, tile is updated on every periodic processing.
- m5 bits 4..0: tile type:

  `00` | bare land
  `01` | 1/3 grass
  `02` | 2/3 grass
  `03` | full grass
  `07` | rough land
  `0B` | rocks
  `0F` | fields; type of fields in m3 bits 3..0 (legal values: 0 through 9) m2: Index into the array of industries (farms), INVALID_INDUSTRY (0xFFFF) if farm has been removed
  `10` | 1/4 snow
  `11` | 2/4 snow
  `12` | 3/4 snow
  `13` | full snow
  `15` | partial desert
  `17` | full desert

- m6 bits 7..6 : Possibility of a bridge above, in the direction specified
- m6 bits 1..0 : Tropic zone definition

`1` | Railway tracks

- m5 bit 7 clear: railway track
  - m1: owner of the track
  - m3 bits 3..0 = track type:

    `0` | conventional railway
    `1` | electrified railway
    `2` | monorail
    `3` | maglev

  - m4 bits 3..0:

    `0` | on bare land
    `1` | on grass, no fences
    `2` | fence on the NW side
    `3` | fence on the SE side
    `4` | fences on the NW and SE sides
    `5` | fence on the NE side
    `6` | fence on the SW side
    `7` | fences on the NE and SW sides
    `8` | fence on the E side (track in the W corner)
    `9` | fence on the W side (track in the E corner)
    `A` | fence on the S side (track in the N corner)
    `B` | fence on the N side (track in the S corner)
    `C` | on snow or desert

  - m5 bits 5..0: track layout: bit set = track present:

    bit 0: | in the X direction
    bit 1: | in the Y direction
    bit 2: | in the north corner (direction W-E)
    bit 3: | in the south corner (direction W-E)
    bit 4: | in the west corner (direction N-S)
    bit 5: | in the east corner (direction N-S)

- m5 bit 7 set: railway depot / checkpoints
  - m1: owner of the depot / checkpoint
  - m2: For waypoints, index into the array of waypoints.
  - m3 bits 3..0 = track type
  - m4 bits 3..0 = ground type, as per m4 bits 3..0 for railway tiles.
  - m5 value C0..C3: railway depot

    m5 bits 1..0
    direction: exit towards:
    `00` | NE
    `01` | SE
    `02` | SW
    `03` | NW

  - m5 value 80..81: checkpoint

    bit 0
    clear | in X direction
    set | in Y direction

- m5 bit 6 set = with signals:
  - m4 bits 7..4: bit clear = signal shows red; same bits as in m3
  - m2 bit 2 (6): set = semaphore signals, clear = light signals (lower and right tracks)
  - m2 bits 1..0 (5..4): type of signal (lower and right tracks)

    `00`: | normal signals
    `01`: | pre-signals
    `10`: | exit-signals
    `11`: | combo-signals

  - m3 bits 7..4: bit set = signal present:
    - For track in the X direction:

      bit 6: | signal in the SW direction
      bit 7: | signal in the NE direction

    - For track in the Y direction:

      bit 6: | signal in the NW direction
      bit 7: | signal in the SE direction

    - For tracks in the W-E direction:

      bit 4: | signal in the W direction on the track in the S corner
      bit 5: | signal in the E direction on the track in the S corner
      bit 6: | signal in the W direction on the track in the N corner
      bit 7: | signal in the E direction on the track in the N corner

    - For tracks in the N-S direction:

      bit 4: | signal in the S direction on the track in the E corner
      bit 5: | signal in the N direction on the track in the E corner
      bit 6: | signal in the S direction on the track in the W corner
      bit 7: | signal in the N direction on the track in the W corner

- m6 bits 7..6 : Possibility of a bridge above, in the direction specified
- m6 bits 1..0 : Tropic zone definition

`2` | Roads

- m5 bits 7..6 clear: road
  - m1: owner of the road type #1
  - m2: Index into the array of towns, 0 for non-town roads
  - m3 bit 7 set = on snow or desert
  - m3 bits 6..4:

    `0` | on bare land
    `1` | on grass
    `2` | paved
    `3` | with streetlights
    `5` | tree-lined
    `6` | on grass with road works
    `7` | paved with road works

  - m3 bits 3..0: counter for the roadworks
  - m4 bits 3..0: road layout road type #1: bit set = road piece present:

    bit 0: | NW piece
    bit 1: | SW piece
    bit 2: | SE piece
    bit 3: | NE piece

  - m4 bits 7..4: road layout road type #2
  - m5 bits 5..4: bits to disallow vehicles to go a specific direction
  - m5 bits 3..0: owner of road type #2
  - m6 bits 5..2: road layout road type #3
  - m7 bits 7..5: road types
  - m7 bits 4..0: owner of road type #3
- m5 bit 7 set, bit 6 clear: road depot
  - m1: owner of the depot
  - m3 bit 7 set = on snow or desert (not displayed, but set internally)
  - m5 bits 3..0 - direction: exit towards: `0` = NE, `1` = SE, `2` = SW, `3` = NW
  - m7 bits 7..5: road types
- m5 bit 6 set, bit 7 clear: level crossing
  - m1: owner of the railway track
  - m2: Index into the array of towns, 0 for non-town roads
  - m3 bit 7 set = on snow or desert
  - m3 bits 6..4: `0` - on bare land, `1` - on grass, `2` or higher - paved
  - m3 bits 3..0: track type
  - m4 bit 6: clear - road in the X direction, set - road in the Y direction (railway track always perpendicular)
  - m4 bit 5: set if crossing lights are on
  - m4 bits 4..0: owner of the road type #1
  - m5 bits 3..0: owner of road type #2
  - m7 bits 7..5: road types
  - m7 bits 4..0: owner of road type #3
- m6 bits 7..6 : Possibility of a bridge above, in the direction specified
- m6 bits 1..0 : Tropic zone definition

`3` | Town building

- m1 : Random bits (newhouses)
- m2 : index into the array of industries
- m3 bit 7 :
  - set : House is complete
    - m5 : age of House. Maximum been 255, which means 255 years and more
  - clear : House is in construction
    - m5 bits 7..5 : free
    - m5 bits 4..3 : construction stage
    - m5 bits 2..0 : construction counter
- m3 bit 6 : 9th bit of house type (m4), allowing 512 different types.
- m3 bits 5..0 : triggers activated (newhouses)
- m4 : town building type (with m3[6] bit)
- m5 : see m3 bit 7
- m6 :
  - If newhouses is activated
    - bits 7..3 : Current animation frame
    - bit 2 : free
  - Standard behaviour
    - bits 7..2 : lift position (for houses type 04 and 05)
  - bits 1..0 : tropic zone specifier
- m7 :
  - If newhouses is activated
    - Periodic processing time remaining
  - Standard behaviour (only for houses type 04 and 05)
    - bits 7..4 : free
    - bits 3..1 : lift destination. Values can be 0..6, except 1.
      So the building has 6 effective floors. This is due to the fact that the first floor is 2 'normal' floors high.
      One 'normal' floor has a height of 6 lift positions.
    - bit 0 : Lift has destination when set

Newhouses is the name englobing a newGRF feature developped by TTDPatch devs (mainly Csaboka).
It allows the replacement of the properties as well as the graphics of houses in the game.
To distinguish between the standard behaviour and the newGRF one, HouseID (m4 + m3[6]) is tested for anything above 110.
110 is the count of standard houses. So above 110 means there is a new definition of at least one house

`4` | Trees

- m1: owner (normally `10`)
- m2 bits 5..4:

  `0` | on grass
  `1` | on rough land
  `2` | on snow or desert; m2 bits 7..6 - amount of snow or desert (for desert always set to 3 in TTD)

- m2 bits 3..0: update counter, incremented on every periodic processing.
  on wraparound the growth status is updated (or, if it's `3`, a random action is taken)
- m3 bits 7..0: type of trees:

  `00`..`0B` | temperate climate trees
  `0C`..`13` | sub-arctic climate trees
  `14`..`1A` | rainforest trees
  `1B` | cactus plants
  `1C`..`1F` | sub-tropical climate, non-rainforest, non-desert trees
  `20`..`28` | toyland trees

  Note: the actually displayed set of trees depends on both type and number of trees
- m4 bits 7..5: type of hedge on the SW border of the tile (1 through 6, or 0=none)
- m4 bits 4..2: type of hedge on the SE border of the tile (1 through 6, or 0=none)
- m5 bits 7..6: number of trees minus one
- m5 bits 2..0: growth status:

  `0`..`2` | one of trees is growing
  `3` | all trees are fully grown
  `4`..`6` | one of trees is withering

- m6 bits 1..0 : Tropic zone definition

`5` | Station tiles

- m1: owner of the station
- m2: index into the array of stations
- m3 bits 7..4: persistent random data for newstations
- m3 bits 3..0: track type for railway stations, must be 0 for all the other stations
- m4: custom station id; 0 means standard graphics
- m5: tile type:

  `00`..`07`

  railway station

  `00`..`01` | open platform
  `02`..`03` | open platform with station building
  `04`....`07` | roofed platform
  bit 0: clear = in X direction, set = in Y direction

  `08`..`33`

  large airport

  `0B` | pad 1
  `16`..`19` | runway middle
  `1A` | runway ending
  `1C` | control tower
  `20` | hangar
  `21` | pad 3
  `22` | pad 2
  `27`..`32` | radar (animated)
  `33` | transmitter

  The initial layout of a large airport is (rows in Y direction, columns in X direction):

      1F 1B 1E 33 26 1A
      09 24 0B 0C 0D 16
      21 1D 23 0E 0F 17
      09 22 0D 11 10 18
      09 08 14 13 12 19
      20 0A 15 1C 27 1A

  `34`..`41`

  small airport

  `3A`..`3D` | field with the wind meter (animated)
  `3E` | runway south ending
  `3F` | runway middle
  `40` | runway north ending
  `41` | hangar

  The initial layout of a small airport is (rows in Y direction, columns in X direction):

      36 3A 40
      35 39 3F
      34 38 3F
      41 37 3E

  `42` | heliport

  `43`..`46`

  lorry loading area : exit towards:

  `43` | NE
  `44` | SE
  `45` | SW
  `46` | NW

  `47`..`4A`

  bus station : exit towards:

  `47` | NE
  `48` | SE
  `49` | SW
  `4A` | NW

  `4B` | oilfield

  `4C`..`51`

  ship dock

  `4C` | SW coast part
  `4D` | NW coast part
  `4E` | NE coast part
  `4F` | SE coast part
  `50` | X direction water part
  `51` | Y direction water part

  `52` | buoy
  `53`..`A7` | used by RichK's larger airports

- m6 bit 3: 1 when a drive through road stop is built over a town owned road, otherwise 0
- m6 bits 1..0 : Tropic zone definition

`6` | Water

- m1: owner (for water and coasts normally `11`)
- m5: tile type:

  `00` | water
  `01` | coast or riverbank

  `10`..`1B`

  canal locks

  `10` | middle part, (SW-NE direction)
  `11` | middle part, (NW-SE direction)
  `12` | middle part, (NE-SW direction)
  `13` | middle part, (SE-NW direction)
  `14` | lower part, (SW-NE direction)
  `15` | lower part, (NW-SE direction)
  `16` | lower part, (NE-SW direction)
  `17` | lower part, (SE-NW direction)
  `18` | upper part, (SW-NE direction)
  `19` | upper part, (NW-SE direction)
  `1A` | upper part, (NE-SW direction)
  `1B` | upper part, (SE-NW direction)

  `80`..`83`

  ship depots

  `80` | ship depot, NE part (X direction)
  `81` | ship depot, SW part (X direction)
  `82` | ship depot, NW part (Y direction)
  `83` | ship depot, SE part (Y direction)

- m6 bits 7..6 : Possibility of a bridge above, in the direction specified
- m6 bits 1..0 : Tropic zone definition

`7` | Void
| Tiles of this class form an invisible, one tile wide border at the south (bottom) edges of the map, so as to protect several algorithms from the consequences of a wraparound at the edges.
`8` | Industry tile

- m1 bit 7: clear = under construction
  - m1 bits 4..2: construction counter, for buildings under construction incremented on every periodic tile processing
  - m1 bits 1..0: stage of construction (`3` = completed), incremented when the construction counter wraps around
    the meaning is different for some animated tiles which are never under construction (types `01`, `1E`..`20`, `30`, `58`; see above)
- m2: index into the array of industries
- m5: type:
  (note: this is not the same as the industry type, which is stored in the array of industries)

  `00`..`06`

  coal mine

  `00` | wheel tower when not animated
  `01` | wheel tower when animated animation state in m3 bits 5..0; m3 bit 6 set = sound already generated

  `07`..`0A`

  power station

  `08` | chimney
  `0A` | transformer; animation progress in m3(valid range `0`..`7`)

  `0B`..`0F` | sawmill

  `10`..`11`

  forest

  `11` | trees cut down

  `12`..`17` | oil refinery
  `18`..`1C` | oil rig

  `1D`..`20`

  oil wells

  `1D` | not animated
  `1E`..`20` | various stages of animation; progress of animation in m3

  `21`..`26` | farm
  `27`..`2A` | factory (temperate climate)
  `2B`..`2E` | printing works

  `2F`..`33`

  copper ore mine

  `2F` | wheel tower when not animated
  `30` | wheel tower when animated; animation state in m3 bits 5..0; m3 bit 6 set = sound already generated
  `31` | chimney

  `34`..`39` | steel mill
  `3A`..`3B` | bank (temperate climate)
  `3C`..`3F` | food processing plant
  `40`..`47` | paper mill

  `48`..`58`

  gold mine

  `4F` | wheel tower when not animated
  `58` | wheel tower when animated; animation state in m3 bits 5..0; m3 bit 6 set = sound already generated

  `59`..`5A` | bank (sub-arctic or sub-tropical climate)
  `5B`..`63` | diamond mine
  `64`..`73` | iron ore mine
  `74` | fruit plantation
  `75` | rubber plantation
  `76`..`77` | water supply
  `78` | water tower
  `79`..`7C` | factory (sub-tropical climate)
  `7D`..`80` | lumber mill

  `81`..`82`

  candyfloss forest

  `82` | candyfloss 'trees' cut down

  `83`..`86` | sweet factory

  `87`..`88`

  battery farm

  `88` | batteries 'reaped'

  `89` | cola wells
  `8A`..`8D` | toy shop

  `8E`..`93`

  toy factory

  `8F` | Animated part; animation state in m3 (valid range `00`..`31`) Tile animation is started (m4 zeroed) on the periodic processing. While the animation is in progress, m4 holds the number of animation cycles that have already taken place. when this number reaches 8 the animation is stopped.

  `94`..`9B` | plastic fountains (various stages of cyclic animation)
  `9C`..`9F` | fizzy drink factory

  `A0`..`A3`

  bubble generator

  `A1` | generators
  `A2` | bubble capture facility; animation state in m3 (valid range `00`..`27`)

  `A4`..`A6`

  toffee quarry

  `A5` | animated part; animation state in m3 (valid range `00`..`45`)

  `A7`..`AE`

  sugar mine

  `AE` | animated part; animation state in m3 (valid range `00`..`5F`)

- m6 bits 1..0 : Tropic zone definition

`9` | Tunnel / bridge

- m5 bits 7..4 clear: tunnel entrance/exit
  - m1: owner of the tunnel
  - m3 bits 3..0 = track type for railway tunnel, must be 0 for road tunnel
  - m4 bit 7 set = on snow or desert
  - m5 bits 3..2: `0` - railway tunnel, `1` - road tunnel
  - m5 bits 1..0 - direction: entrance towards: `0` = NE, `1` = SE, `2` = SW, `3` = NW
- m5 bit 7 set: bridge ramp
  - m1: owner of the bridge
  - m2 bits 7..4: bridge type:

    Type | Max. speed (mph) | Description
    --- | --- | ---
    `0` | 20 | wooden
    `1` | 30 | concrete
    `2` | 40 | girder, steel
    `3` | 50 | suspension, concrete
    `4` | 60 | suspension, steel
    `5` | 70 | suspension, steel
    `6` | 100 | cantilever, steel
    `7` | 130 | cantilever, steel
    `8` | 150 | cantilever, steel
    `9` | 160 | girder, steel
    `A` | 200 | tubular, steel

  - m3 bits 3..0 = type of track on the bridge, must be 0 for road bridge
  - m4 bit 7 set = on snow or desert
  - m5 bits 3..2: `0` - railway bridge, `1` - road bridge
  - m5 bits 1..0: DiagDirection onto the bridge
- m6 bits 7..6 : Possibility of a bridge above, in the direction specified
- m6 bits 1..0 : Tropic zone definition

`A` | `Unmovables`

- m1 : owner of the object (for lighthouses and transmitters normally `10`)
- m2 :
  - for company statue (m5 = 02), TownID on which the statue is built in
- m5 : tile type:

  `00` | transmitter
  `01` | lighthouse
  `02` | company statue
  `03` | company-owned land
  `80`..`93` | company headquarters (5 sets of 4 tiles each, updated quarterly depending on the company performance)

- m6 bits 7..6 : Possibility of a bridge above, in the direction specified
- m6 bits 1..0 : Tropic zone definition

Classes `B` through `F` are reserved. The presence of a tile in one of the reserved classes will crash OTTD.

Original Copyright © 2003 by Marcin Grzegorczyk for TTDLX.
Transport Tycoon and Transport Tycoon Deluxe are Copyright © by Chris Sawyer.
All the other trademarks are the property of their respective owners.