NML:Railtypes

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Props, Vars and CBs

Railtypes can only be defined in OpenTTD Supported by OpenTTD 1.0 (r18969)1.0 or later.


Railtype IDs

Railtype IDs are limited to 16 in total. NewGRF-local IDs may freely be chosen, but must be in the 0..15 range. If other railtype GRFs are loaded, it may be that there are not enough railtype slots available. To prevent your entire NewGRF from being deactivated with the 'Attempt to use invalid ID'-error, you can use the following code: 

if (railtype_available("LABL") || loading_stage == LOADING_STAGE_RESERVE)
    ... item definition ...
} else if (loading_stage == LOADING_STAGE_ACTIVATE) {
    ... warning / error ...
}

The warning / error is optional, but can be used to inform the user about the missing railtypes.

Railtype properties

property value range comment
label 4-byte string names of default rail types: "RAIL", "ELRL", "MONO", "MGLV". See the List of railtype labels in the NewGRF Specs for currently defined custom labels.
introduction_date date(yyyy,mm,dd)

Supported by OpenTTD 1.1 (r21842)1.1 Valid range for yyyy is 0 ... 5000000.

name string Name of this railtype
toolbar_caption string Supported by OpenTTD 1.2 (23129)1.2 Not supported by TTDPatch Caption of the build rail toolbar. In earlier versions this is the same as the 'name'
menu_text string Shown in the dropdown menu for all railtypes
build_window_caption string Caption of the build vehicle window
autoreplace_text string String for the autoreplace window
new_engine_text string String for the "We have invented a new <rail type> engine" news message
compatible_railtype_list list of railtype labels Provide a list of rail types that trains of this type can also run on. e.g. ["RAIL", "ELRL", "MONO"]
powered_railtype_list list of railtype labels Provide a list of rail types that trains of this type are powered on.
railtype_flags bitmask(RAILTYPE_FLAG_XXX, ...) XXX = [CATENARY | NO_LEVEL_CROSSING] Flags enable catenary and/or disable level crossings.
curve_speed_multiplier 0...65525 max curve speed is defined as multiple of the base curve speed (see below)
station_graphics RAILTYPE_STATION_NORMAL, RAILTYPE_STATION_MONORAIL, RAILTYPE_STATION_MAGLEV Type of station graphics to use for the default stations
construction_cost 0 ... 65525

Supported by OpenTTD 1.1 (r19307)1.1 per piece of track as multiplier to PR_BUILD_RAIL base cost. Default cost factors are 8, 12, 16 and 24 for RAIL, ELRL, MONO and MGLV.

speed_limit 0 ... 65525 km/h (speed units) A speed limit of 0 means unlimited speed
acceleration_model ACC_MODEL_RAIL, ACC_MODEL_MONORAIL, ACC_MODEL_MAGLEV ACC_MODEL_RAIL and ACC_MODEL_MONORAIL behave the same currently
map_colour 0 ... 255

Supported by OpenTTD 1.1 (r19307)1.1 entry in the colour palette.

requires_railtype_list list of railtype labels

Supported by OpenTTD 1.1 (r21842)1.1 List of rail types on that need to be available to the company of the player for this rail type to be introduced at (or after) the introduction date. This limit does not apply when the rail type is introduced by the introduction of a vehicle.

introduces_railtype_list list of railtype labels

Supported by OpenTTD 1.1 (r21841)1.1 List of rail types that get introduced when this rail type is introduced. For example, to make sure that when a fast rail type is introduced the slow variant exists.

sort_order 0 ... 255

Supported by OpenTTD 1.1 (r21866)1.1 number which defines the sort order among rail types. If this entry is not defined, it gets assigned sort order n*10+7 for the n-th railtype.

maintenance_cost

Supported by OpenTTD 1.2 (r23415)1.2 Maintenance cost factor for each piece of tracks of this railtype. Default cost factors are 8, 12, 16 and 24 for RAIL, ELRL, MONO and MGLV.

alternative_railtype_list list of railtype labels

Supported by OpenTTD 1.2 (r23758)1.2 List or rail types which this rail type will act as fallback for, if the corresponding rail type is not defined separately

Sort order

The sort_order influences the sort order of the drop down lists with rail types. Default values are as follows:

Value Meaning
07 normal rail
17 electrified rail
27 monorail
37 maglev
n7 railtype #n

Thus the rail type that (internally) gets index 8 will get a default value of 87. These defaults are to keep the ordering when this property is not supported as they were.

Base speeds for curves

The base speeds relevant for the curve_speed_multiplier are:

curve length base speed [km/h]
0 (90 degree turn) 30
1 44
2 55
3 66
4 75
5 84
6 91
7 98
8 103
9 108
10 111
11 114
12+ 115

Railtype variables

name value range comment
terrain_type TILETYPE_NORMAL, TILETYPE_DESERT, TILETYPE_RAIN_FOREST, TILETYPE_SNOW
enhanced_tunnels 0 should custom tunnel entrances be modified other values than 0 might be returned
level_crossing_status LEVEL_CROSSING_CLOSED, LEVEL_CROSSING_OPEN
build_date 0 .. 5000000 for depots only: build date of the depot in days since 0
town_zone town zone Town zone of the tile. (Only available for level crossings and depots.)

Railtype callbacks

For rail types a number of callbacks are used to define rail type graphics. Each should refer to a sprite set containing the relevant sprites. Refer to the example sprites or the example railtype grf in the NML repository, for an example on what sprites are needed in what order.

callbacks number of sprites meaning
gui 16 4 rail directions, autorail, depot, tunnel and convert rail sprites for rail menu.
track_overlay[1] 10 6 flat and 4 slope sprites. Track without landscape. Used in junctions and PBS.
underlay[1] 16 6 flat and 4 slope, one crossing WITH track, 5 junction pieces without track. Tracks with ballast but without landscape.
tunnels[1] 4 1 sprite for each direction. Sprite is overlay for track in existing tunnel graphics. The original ground sprite is drawn, then the overlay, then possibly a train and the original tunnel head is drawn over the top. This keeps compatibility with different landscape types. Sprite order: SW, NW, NE, SE.
catenary_wire 28
catenary_pylons 8
bridge_surfaces[1] 6
level_crossings[1] 10 For each direction: one track sprite and 4 sprites for road lights etc
depots[2] 6 2 sprites for each south-ish, 1 sprite for each north-ish depot. Like original depots.
fences 8 x, y, vertical, horizontal, SW, SE, NE and NW slopes like original fences at sprite 1301.
tunnel_overlay[3] 4 If this callback is defined, tunnels for this railtype will be drawn differently. First, a grass underlay base sprite is drawn, then the 'tunnels'-sprite. Next, train sprites if applicable and then a grass overlay and finally the sprite from this type (tunnel_overlay). The grass sprites are defined in the base set and do not contain any parts of the tracks or portal, so these have to be fully provided by the railtype sprites. extra_callback_info1 contains 0 for normal tunnels, without any extra features (like tracks above). All other values are reserved for future extensions.
signals 8 Supported by OpenTTD 1.3 (r24367)1.3 1 sprite for each direction, order is SW(-facing), NE, SE, NW, E, W, S, N. For more information, see below
  1. ↑ 1.0 1.1 1.2 1.3 1.4 Either all or none of these sprites should be provided.
  2. ↑ Supported by OpenTTD 1.2 (r22854)1.2 In OpenTTD prior to r22854, depot sprites would not be used if the above 'all or none' sprites were not supplied.
  3. ↑ Above 'all or none' sprites must be supplied, if these sprites are to be used.

If a callback is not implemented or fails, graphics from the fallback railtype (picked via the station_graphics property) will be used instead.
Note that there is no "default graphics"-callback.

Example sprites

gui

Railtype gui.png

track_overlay

Railtype overlay.png

underlay

Railtype underlay.png

level_crossings

You can define a special track piece which crosses the road and for each of two directions and each of the corners of the tile a separate sprite for a light, sign, or whatever should go there.

Sprite number for X Sprite number for Y Useage
0    1    Rail overlay
2    3    North light
4    5    East light
6    7    West light
8    9    South light

Railtype levelcrossing.png

depots

Sprite Number Usage
0    NE wall for SE-entry depot.
1    Depot building for SE-entry depot.
2    NW wall for SW-entry depot.
3    Depot building for SW-entry depot.
4    Depot building for NE-entry depot.
5    Depot building for NW-entry depot.

fences

Railtype fences.png

tunnel_overlay

If this callback is defined, tunnels for this railtype will be drawn differently.

First, a grass underlay base sprite is drawn, then the 'tunnels'-sprite. Next, train sprites if applicable and then a grass overlay and finally the sprite from this callback. The grass sprites are defined in the base set and do not contain any parts of the tracks or portal, so these have to be fully provided by the railtype sprites.

Illustration: RailtypeTunnelExample.png

signals

This callback can be used to supply custom signal graphics.

The resulting sprite set must consist of 8 sprites, corresponding to the following signal directions: SW-facing, NE-facing, NW-facing, SE-facing, E-facing, W-facing, S-facing, N-facing. Variable extra_callback_info2 contains information about the kind of signal to be drawn. If resolving fails or results in an empty sprite group, the matching base set sprite will be used instead.

Format of extra_callback_info2: 0xRRTTVVSS

TT: Signal type Meaning
0 Normal block signal
1 Entry pre-signal
2 Exit pre-signal
3 Combo pre-signal
4 Two-way path signal
5 One-way path signal
all other values Reserved


VV: Signal variant Meaning
0 Light (electric) signal
1 Semaphore
all other values Reserved


SS: Signal state Meaning
0 Red signal
1 Green signal
all other values Reserved

The most significant byte (RR) is reserved and must be and-masked out.

extra_callback_info1 can be used to distinguish between map and GUI sprites:

Lowest byte of variable 10 Meaning
0 Signal is drawn in a viewport, i.e. on the map.
0x10 Signal is drawn in the signal GUI. The returned sprite set must still have 8 sprites, but OpenTTD will only use the 7th sprite, so all other sprites can be empty.
all other values Reserved

The other bytes of extra_callback_info1 are reserved, and must be masked.


Example code

A typical implementation for railtypes can look like: 

 item(FEAT_RAILTYPES, elrail, 0x01) {
     property {
         label:                      "SHIN";
         name:                       string(STR_EL_RAIL);
         menu_text:                  string(STR_EL_RAIL);
         build_window_caption:       string(STR_BUILD_CAPTION);
         autoreplace_text:           string(STR_AUTOREPLACE);
         new_engine_text:            string(STR_NEW_ENGINE);
         compatile_railtype_list:    ["SHIN","RAIL","ELRL"];                   // Tracks of rail and electrified rail are compatible
         powered_railtype_list:      ["ELRL","SHIN"];                          // But we got only power when we have electricity
         railtype_flags:             bitmask(RAILTYPE_FLAG_NO_LEVEL_CROSSING); // High speed tracks should not have level crossings
         curve_speed_multiplier:     1;
         station_graphics:           RAILTYPE_STATION_MAGLEV;                  // We want the most modern stations
         construction_cost:          32;                                       // should be pretty steep
         speed_limit:                500 km/h;
         acceleration_model:         ACC_MODEL_RAIL;                           // This is still rail, though
     }
     graphics {
         track_overlay:   ground_switch_overlay;     // defines the sprites drawn as overlay for junctions and highlight
         underlay:        ground_switch_underlay;    // defines the usual tracks and the underlay for junctions
         level_crossings: level_crossing_switch;     // defines level crossings including traffic lights and blocking bars
         tunnels:         tunnel_switch;             // defines the tracks drawn on a funnel tile
         depots:          depot_switch_electric;     // defines the depot sprites
         bridge_surfaces: bridge_terrain_switch;     // defines the overlay drawn over bridges
         fences:          fences_set;                // defines the look of fences
         // we don't define catenery wire and pylons, thus we use the default which comes with the base graphics.
     }
 }

The switches and graphics blocks are defined in the usual way as described in sections switches, random switches and graphics block sections.

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