Road and Tram types

The code for road and tram types consists of three parts:

• the road/tram type's definition
• a 'chain' of performance functions for the road/tram type, considering game-intrinsic variables and including its graphics
• the road/tram type's activation

The definition sets the feature properties of the road/tram type like its label, related texts, speedlimit, etc. Please note that a road/tram type definition may only occur after a prior grfinit() function call for the newGRF file.

The road/tram type's performance functions are used to group sets of graphics sprites from a previous spriteblock(), or to evaluate game-intrinsic variables, and make both of them accessible to the road/tram type's activation function.

The road/tram type activation instantiates the road/tram type by finally assigning graphics sets to a particular road/tram type element (icon, road/tram underlay, tunnel, catenary, ...). This is done by supplying a block of special functions handling references and road/tram type elements to the road/tram type's activation. See below.

Function	Meaning
defineroadtype/definetramtype(<Label>, <block>)	Road/tram type definition
makeroadtype/maketramtype(<Label>, <block>)	Road/tram type activation

defineroadtype/definetramtype(<Label>, <block>)

This function defines a road/tram type. Its parameters are the road/tram type's label and a block of property-defining functions, where the relative position of the property functions is irrelevant.

Please note that the label has to be quoted like this: {HWAY}.

Road/tram type IDs are newGRF local, with an ID to label mapping. Therefore, to modify an existing road/tram type, specify its label in defineroadtype/definetramtype(). To create a new road/tram type, again just specify its label in defineroadtype/definetramtype(). If a label clashes with another newGRF, then one newGRF will end up modifying the properties instead of creating a new road/tram type. At the time being, there are 63 road/track IDs available (0 .. 62).

Reserved labels for default road/tram types are: ROAD (default road), ELRD (electrified road), RAIL (default tram), ELRL (electrified tram).

deftxt(rt_tool,
	US, "Motorway construction",
	UK, "Motorway construction",
	D, "Autobahnbau",
	F, UTF8 "Construction autoroutière",
	E, UTF8 "Construccíon de carreteras",
)

...

defineroadtype({HWAY},
	toolbartext(rt_tool)
	menutext(rt_menu)
	vehwindowtext(rt_window)
	autoreplacetext(rt_autoreplace)
	newenginetext(rt_engine)
	powered_list({"ROAD"})
	roadtypeflags(RT_HOUS)
	costfactor(100)
	speedlimit(130 km/h)
	mapcolour(170)
)

makeroadtype/maketramtype(<Label>, <block>)

This function activates a previously defined road/tram type. Its parameters are the road/tram type's label and a block of special road/tram type feature-associated functions:

Function	Meaning
link(<ref()>, <road/tram_type_element>)	Linking a chain of graphics or variable dependencies to a specific road/tram type element
default(<ref()>)	Default chain to use with this road/tram type

Road/tram type elements assign certain types of graphics defined by their associated chains:

Road/tram type element	Sprite type	Num sprites	Usage
RT_ICON	Icons and cursors[*]	12	4 road/tram directions, autoroad, depot, convert road/tram. First all icons, then all cursors
RT_OLAY	Road/tram track overlays [*]	19	11 combinations, 4 slope pieces, and 4 dead ends. Sprites should contain only the the road/tram track, with no landscape
RT_ULAY	Underlay[*]	19	same as RT_OLAY
RT_WIRE	Catenary wire	29	11 track combinations, 4 slopes, 4 dead ends, 4 tunnels, 2 middle bridge, and 4 bridge ramps
RT_PYLN	Catenary pylons	29	same as above, only tunnels unused
RT_BRDG	Bridge surfaces[*]	6	2 middle bridge, and 4 bridge ramps
RT_DEPO	Depots	6	2 sprites for each southern view, 1 sprite for each northern view, following the original layout for depot sprites
RT_STOP	Road stop	4	overlays for drive-in road stops

[*] These sprites must be provided, the others may be left out if not needed.

Depot sprites:

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

makeroadtype(HWAY,
	link(ref(7), RT_ICON)  // icons and cursors
	link(ref(11), RT_OLAY) // track overlays for junctions and PBS
	link(ref(2), RT_ULAY)  // track underlays
	link(ref(4), RT_BRDG)  // bridge surfaces
	link(ref(8), RT_DEPO)  // depot sprites
	link(ref(10), RT_PYLN) // catenary pylons
	link(ref(9), RT_WIRE)  // catenary wires
	default(cbfail())      // s.b.
)