Landscape

Seven attributes hold the information about a tile. These attributes are type_height, m0, m1, m2, m3, m4, m5 and m7.

The attribute type_height contains the height of a tile stored in its lower 4 bits. The slope of a tile is computed combining its height with the heights of its neighbours. The higher bits of type_height may contain additional information depending on the climate; currently, the higher 2 bits contain the zone information in the tropical climate.

The zones currently defined for the tropical climate are the following.

Tile contents

The attributes m0 … m7 define the contents of a tile proper, ie, what is built on the tile. Generally speaking, the higher bits of m0 determine the kind of object that is on the tile (its "class"). Also, the lower 2 bits of m0 record whether there is a bridge over the tile, for tile classes that allow this. m1 contains the owner of the tile and, for tile classes representing an indexed object, m2 contains the index of this object into the corresponding array. The values of m3, m4, m5 and m7 are highly dependent on the object class.

The following table describes the full encoding used in storing objects into the tile structure; the possible values for each field are described below.

Legend: XX class mark; 00 free; XX abused for different purposes

Field values

Bridge above

Whether there is a bridge above the tile, and its direction.

Direction

Owner

Owner of the tile or piece of road.

Update counter

An update counter is used in tiles that are to remain in a certain state for a period of time and then change. The counter is increased on every periodic processing of the tile, and the corresponding action is taken when the counter reaches a preset value or wraps around.

Ground and density

Ground type (grass, snow, desert, …) and density for clear or tree tiles.

Hedge

Hedge on the border of a tile. It can take the values 1 through 6, or 0 for none.

Trees

Both the number and type of trees fields jointly determine the set of trees actually displayed at a tile. The lower 3 bits of the number field represent the growth status of the trees (0…2 for growing; 3 for fully grown; 4…7 for withering).

Water tile types

Object types

Bridge types

Track types

Track layout

PBS track reservations

Ground and fence for railway tracks

Signals

Present road types

Ground and pavement for roads

Road layout

Tunnels

Industries

• m1 bit 7: clear: under construction
  • m1 bits 6…5: water class (sea, canal, river or land)
  • m1 bits 3…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)
• m2: index into the array of industries
• m3: random bits (NewGRF)
• m4: animation loop
• m5: industry tile type (with m0 bit 3)
• m7: animation frame
• m0 bit 3: bit 8 of type (see m5)
• m0 bits 2…0: random triggers (NewGRF)

Houses

• m1: random bits (Newhouses)
• m2: index into the array of towns
• m3 bit 7:
  • set: house is complete
    • m5: age of house in years, clamped at 255
  • clear: house is under construction
    • m5 bits 4…3: construction stage
    • m5 bits 2…0: construction counter
• m3 bit 6: bit 8 of house type (see m4), allowing 512 different types.
• m3 bit 5: free
• m3 bits 4…0: triggers activated (Newhouses)
• m4: town building type (with m3 bit 6)
• m5: see m3 bit 7
• m0 bits 5…0:
  • If Newhouses is activated: periodic processing time remaining
  • Standard behaviour: lift position (only for houses type 04 and 05)
• m7:
  • If Newhouses is activated: current animation frame
  • Standard behaviour: (only for houses type 04 and 05)
    • 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 developed 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 anything above 110 means that there is a new definition of at least one house.