Road vehicles

The code for a road vehicle consists of three parts:

• the vehicle's definition
• a 'chain' of performance functions representing 'flow of control' for the vehicle, considering game-intrinsic variables and including its graphics
• the vehicle's activation

The definition sets the properties of the road vehicle like introduction date, top speed, capacity, etc. Please note that a vehicle definition may only occur after a prior grfinit() function call for the grf file.

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

The vehicle activation instantiates the vehicle by finally assigning graphics sets and/or callback or other variable-referencing functions to this particular vehicle. This is done by supplying a block of special functions handling references and cargo types to the vehicle's activation. See below.

Function	Meaning
definevehicle(<Veh-ID>, List::(<Language-ID>, <String>) | <String>,<block>)	Road vehicle definition
namevehicle(<Veh-ID>, List::(<Language-ID>, <String>))	Definition of road vehicle's name(s)
makevehicle(<Veh-ID<, <block<)	Road vehicle activation

This function defines a road vehicle. Its parameters are the road vehicle's ID, an optional standard text naming the vehicle (or a namevehicle block, s.b.), and a block of property-defining functions, where the relative position of the property functions is irrelevant.

definevehicle(_BÜSSING_NAGD2,{"Büssing-NAG D2"},
        intro(1928)
        reliability(22)
        vehlife(16)
        modlife(21)
        loadamount(11)
        climate(TEMPERATE, ARCTIC, TROPIC)
        speed(55 km/h)
        runningcost(18)
        runningcostbase(0x4c48)
        newgraphics()
        capacity(61)
        cargotype(PASS)
        price(17)
        soundeffect(BUS_START)
        power(70 PS)
        weight(7 t)
        cargomask(NONE)
        callbacks(CB_WLEN)
        effort(15 KN)
        airdrag(0)
        retire(7)
        flags(2CC)
        cargoclasses(+PASS)
)

This function defines more names for a road vehicle than the default one given by definevehicle(). It should be used if a road vehicle needs names in more than one language. Its parameters are the road vehicle's ID and a block consisting of language IDs and associated names.

See example in the trains section.

Alternatively, you may use a namevehicle block as the second parameter for function definevehicle(). This might be beneficial in situations where a vehicle's name would be different in a number of languages, and those would be stored in an extra file, to keep them together, see example in the trains section.

makevehicle(<Veh-ID<, <block<)

This function activates a previously defined road vehicle. Its parameters are the road vehicle's ID and a block of special cargo-associated functions:

Function	Meaning
link(<ref()>,<CargoType>)	Linking a chain of graphics or variable-dependencies to this vehicle
default(<ref()>)	Default chain to use with this vehicle

link(<ref()>,<CargoType>)

This function links a reference to a chain of functions describing graphics and/or variable evaluations with a particular cargo type. Its parameters are the reference to the chain of functions and a cargo type.

The given cargo-type determines the set of graphics or the variable chain to be used with this particular type of cargo. If the grf file has installed a cargo translation table, the cargo type here refers to the cargo with that label in the translation table.

The special cargo-type MENU is used for graphics shown in the purchase or construction window.

default(<ref()>)

This function is used if no entry from the link() function(s) matches, or if there are no special cargo-types listed at all in a link() function.

• Callback tutorial