Method DetermineCapacity

src/engine.cpp:200–274

* Determines capacity of a given vehicle from scratch. * For aircraft the main capacity is determined. Mail might be present as well. * @param v Vehicle of interest; nullptr in purchase list * @param mail_capacity returns secondary cargo (mail) capacity of aircraft * @return Capacity */

 * @return Capacity
 */
uint Engine::DetermineCapacity(const Vehicle *v, uint16_t *mail_capacity) const
{
	assert(v == nullptr || this->index == v->engine_type);
	if (mail_capacity != nullptr) *mail_capacity = 0;

	if (!this->CanCarryCargo()) return 0;

	bool new_multipliers = this->info.misc_flags.Test(EngineMiscFlag::NoDefaultCargoMultiplier);
	CargoType default_cargo = this->GetDefaultCargoType();
	CargoType cargo_type = (v != nullptr) ? v->cargo_type : default_cargo;

	if (mail_capacity != nullptr && this->type == VEH_AIRCRAFT && IsCargoInClass(cargo_type, CargoClass::Passengers)) {
		*mail_capacity = GetEngineProperty(this->index, PROP_AIRCRAFT_MAIL_CAPACITY, this->VehInfo<AircraftVehicleInfo>().mail_capacity, v);
	}

	/* Check the refit capacity callback if we are not in the default configuration, or if we are using the new multiplier algorithm. */
	if (this->info.callback_mask.Test(VehicleCallbackMask::RefitCapacity) &&
			(new_multipliers || default_cargo != cargo_type || (v != nullptr && v->cargo_subtype != 0))) {
		uint16_t callback = GetVehicleCallback(CBID_VEHICLE_REFIT_CAPACITY, 0, 0, this->index, v);
		if (callback != CALLBACK_FAILED) return callback;
	}

	/* Get capacity according to property resp. CB */
	uint capacity;
	uint extra_mail_cap = 0;
	switch (this->type) {
		case VEH_TRAIN:
			capacity = GetEngineProperty(this->index, PROP_TRAIN_CARGO_CAPACITY,        this->VehInfo<RailVehicleInfo>().capacity, v);

			/* In purchase list add the capacity of the second head. Always use the plain property for this. */
			if (v == nullptr && this->VehInfo<RailVehicleInfo>().railveh_type == RAILVEH_MULTIHEAD) capacity += this->VehInfo<RailVehicleInfo>().capacity;
			break;

		case VEH_ROAD:
			capacity = GetEngineProperty(this->index, PROP_ROADVEH_CARGO_CAPACITY,      this->VehInfo<RoadVehicleInfo>().capacity, v);
			break;

		case VEH_SHIP:
			capacity = GetEngineProperty(this->index, PROP_SHIP_CARGO_CAPACITY,         this->VehInfo<ShipVehicleInfo>().capacity, v);
			break;

		case VEH_AIRCRAFT:
			capacity = GetEngineProperty(this->index, PROP_AIRCRAFT_PASSENGER_CAPACITY, this->VehInfo<AircraftVehicleInfo>().passenger_capacity, v);
			if (!IsCargoInClass(cargo_type, CargoClass::Passengers)) {
				extra_mail_cap = GetEngineProperty(this->index, PROP_AIRCRAFT_MAIL_CAPACITY, this->VehInfo<AircraftVehicleInfo>().mail_capacity, v);
			}
			if (IsValidCargoType(GetCargoTypeByLabel(CT_MAIL))) {
				if (!new_multipliers && cargo_type == GetCargoTypeByLabel(CT_MAIL)) return capacity + extra_mail_cap;
			}
			default_cargo = GetCargoTypeByLabel(CT_PASSENGERS); // Always use 'passengers' wrt. cargo multipliers
			break;

		default: NOT_REACHED();
	}

	if (!new_multipliers) {
		/* Use the passenger multiplier for mail as well */
		capacity += extra_mail_cap;