NML:Airports

Airports and airport tiles can only be defined in OpenTTD 1.1 or later.

Airport properties

name	value range	comment
name	string	1.1 Name of the airport
override		1.1 the id of airport to replace / override
layouts	list of layouts	1.1
years_available	[start year, last year]	1.1 list of the availablility years: first and last year it can be built
ttd_airport-type	0 ... 3	1.1 substitute TTDPatch airport type
catchment_area		1.1 catchment area of the airport in tiles around its perimeter
noise_level		1.1 noise generation of this airport

Airport tile properties

name	value range	comment
override		1.1 the id of airport tile to override
substitute		1.1 the id of airport tile to replace
callback_flags	bitmask	1.1 Do not set this, unless you use old-style callbacks.
animation_info		1.1
animation_speed		1.1 see speed settings
animation_triggers	bitmask(ANIM_TRIGGER_APT_XXX, ... )	1.1 Bitmask of triggers that will trigger the anim_control callback, see the table below.

Airport variables

name	value range	comment
layout	0 .. (number of layouts - 1)	1.1 Layout number of the airport (index in the layouts array)

Airport tile variables

name	value range	comment
terrain_type
town_radius_group
relative_x	0..255	X-coordinate (top right -> bottom left) of the tile relative to the northernmost tile.
relative_y	0..255	Y-coordinate (top left -> bottom right) of the tile relative to the northernmost tile.
relative_pos	0xYYXX	A combination of relative_x and relative_y in the format 0xYYXX. Useful if you want to check for a single position. The builtin function relative_coord(x, y) may be useful when making comparisons.
animation_frame

The following variables require a signed x,y offset as parameters. The offset is relative to the current tile. Offset 0,0 means the current tile.

name	value range	comment
nearby_tile_slope	SLOPE_XXX	See tile slopes for an overview of possible values
nearby_tile_is_same_airport	1 if the tile is part of the same airport, 0 otherwise
nearby_tile_is_water	1 if the tile is water, 0 otherwise
nearby_tile_terrain_type	TILETYPE_XX	TILETYPE_NORMAL, TILETYPE_DESERT, TILETYPE_RAIN_FOREST, TILETYPE_SNOW
nearby_tile_water_class	WATER_CLASS_XXX	SEA | CANAL | RIVER] Note that tiles for which nearby_tile_is_water is 0 may still have a water class, e.g. industry tiles with water beneath them.
nearby_tile_height	0..120	The height of the lowest corner of the given tile.
nearby_tile_class	Tile class
nearby_tile_animation_frame	0..255	Animation frame of the given tile
nearby_tile_airporttile_id	0x00aa, 0xFFbb, 0xFFFE or 0xFFFF	0x00aa: The tile is an airport tile that is part of this GRF, the tile id is aa. 0xFFbb: The tile is an original airport tile with id bb. 0xFFFE: The tile is an airport tile defined in another GRF. 0xFFFF: The tile is not an airport tile or it belongs to another GRF.

Airport callbacks

callback	return value	comment
default	Sprite set (with 1 sprite)	Preview graphics to use in the build menu. One sprite per layout may be given, use the layout to distinguish between layouts.
additional_text	String	Additional text to show in the buy menu. String may differ per layout, use the layout variable for this.
layout_name	String	Name of the airport layout in the variable layout

Note that, although the airport isn't built yet, the layout variable is always available and set to the layout the user has selected in the GUI.

Airport tile callbacks

callback	return value	comment
default	Sprite layout	Graphics for an airport tile
anim_next_frame	Next animation frame or CB_RESULT_XXX	Called for every animation frame, returns the next frame to display. Alternatively, return CB_RESULT_NEXT_FRAME or CB_RESULT_STOP_ANIMATION to show the next frame or stop animation, respectively. extra_callback_info1 contains random bits. Returning a sound effect in the high byte will cause that sound effect to be played.
anim_control	Next animation frame or CB_RESULT_XXX	Called whenever an animation trigger happens. Return the animation frame to show, or CB_RESULT_XXX with XXX = [CB_RESULT_START_ANIMATION | STOP_ANIMATION | DO_NOTHING] to respectively start the animation in its current frame, stop the animation or do nothing. extra_callback_info1 contains random bits. Returning a sound effect in the high byte will cause that sound effect to be played. extra_callback_info2 contains the reason to trigger the animation, see the table below. Note that you need to enable the wanted triggers in the animation_triggers property.
anim_speed	0 .. 16	Decide the time an animation frame should last. Return value is interpreted as (num_ticks = 2^anim_speed), which each tick lasting 30 ms. Avoid using this callback if possible, since it has to be called each tick for every animated tile. This can be used to create animation frames that last between 30 ms and 33 minutes.
foundations	CB_RESULT[_NO]_FOUNDATIONS	Return CB_RESULT_FOUNDATIONS to draw standard foundations (default) or CB_RESULT_NO_FOUNDATIONS to not draw them.

Animation triggers

Animation trigger	Description
ANIM_TRIGGER_APT_BUILT	Airport is built (all tiles at the same time)
ANIM_TRIGGER_APT_TILELOOP	Airport tile is processed in the tileloop (at different times for different tiles)
ANIM_TRIGGER_APT_NEW_CARGO	New cargo arrives at the airport (all tiles at the same time)
ANIM_TRIGGER_APT_CARGO_TAKEN	All cargo of a cargo type is removed from the airport (all tiles at the same time)
ANIM_TRIGGER_APT_250_TICKS	Every 250 ticks (all tiles at the same time)