Function GetLoadAmount

src/economy.cpp:1298–1331

* Gets the amount of cargo the given vehicle can load in the current tick. * This is only about loading speed. The free capacity is ignored. * @param v Vehicle to be queried. * @return Amount of cargo the vehicle can load at once. */

 * @return Amount of cargo the vehicle can load at once.
 */
static uint GetLoadAmount(Vehicle *v)
{
	const Engine *e = v->GetEngine();
	uint load_amount = e->info.load_amount;

	/* The default loadamount for mail is 1/4 of the load amount for passengers */
	bool air_mail = v->type == VEH_AIRCRAFT && !Aircraft::From(v)->IsNormalAircraft();
	if (air_mail) load_amount = CeilDiv(load_amount, 4);

	if (_settings_game.order.gradual_loading) {
		uint16_t cb_load_amount = CALLBACK_FAILED;
		if (e->GetGRF() != nullptr && e->GetGRF()->grf_version >= 8) {
			/* Use callback 36 */
			cb_load_amount = GetVehicleProperty(v, PROP_VEHICLE_LOAD_AMOUNT, CALLBACK_FAILED);
		} else if (e->info.callback_mask.Test(VehicleCallbackMask::LoadAmount)) {
			/* Use callback 12 */
			cb_load_amount = GetVehicleCallback(CBID_VEHICLE_LOAD_AMOUNT, 0, 0, v->engine_type, v);
		}
		if (cb_load_amount != CALLBACK_FAILED) {
			if (e->GetGRF()->grf_version < 8) cb_load_amount = GB(cb_load_amount, 0, 8);
			if (cb_load_amount >= 0x100) {
				ErrorUnknownCallbackResult(e->GetGRFID(), CBID_VEHICLE_LOAD_AMOUNT, cb_load_amount);
			} else if (cb_load_amount != 0) {
				load_amount = cb_load_amount;
			}
		}
	}

	/* Scale load amount the same as capacity */
	if (e->info.misc_flags.Test(EngineMiscFlag::NoDefaultCargoMultiplier) && !air_mail) load_amount = CeilDiv(load_amount * CargoSpec::Get(v->cargo_type)->multiplier, 0x100);

	/* Zero load amount breaks a lot of things. */
	return std::max(1u, load_amount);
}

/**
 * Iterate the articulated parts of a vehicle, also considering the special cases of "normal"