1 files changed, 59 insertions, 0 deletions
diff --git a/src/vehicle.cpp b/src/vehicle.cpp
index c1e99f85b..2fbc9a6ac 100644
--- a/src/vehicle.cpp
+++ b/src/vehicle.cpp
@@ -1418,6 +1418,65 @@ SpriteID GetVehiclePalette(const Vehicle *v)
 	return GetEngineColourMap(v->engine_type, v->owner, INVALID_ENGINE, v);
 }
 
+/**
+ * Determines capacity of a given vehicle from scratch.
+ * For aircraft the main capacity is determined. Mail might be present as well.
+ * @note Keep this function consistent with Engine::GetDisplayDefaultCapacity().
+ * @param v Vehicle of interest
+ * @return Capacity
+ */
+uint GetVehicleCapacity(const Vehicle *v)
+{
+	const Engine *e = Engine::Get(v->engine_type);
+
+	if (!e->CanCarryCargo()) return 0;
+
+	CargoID default_cargo = e->GetDefaultCargoType();
+
+	/* Check the refit capacity callback if we are not in the default configuration.
+	 * Note: This might change to become more consistent/flexible/sane, esp. when default cargo is first refittable. */
+	if (HasBit(e->info.callback_mask, CBM_VEHICLE_REFIT_CAPACITY) &&
+			(default_cargo != v->cargo_type || v->cargo_subtype != 0)) {
+		uint16 callback = GetVehicleCallback(CBID_VEHICLE_REFIT_CAPACITY, 0, 0, v->engine_type, v);
+		if (callback != CALLBACK_FAILED) return callback;
+	}
+
+	/* Get capacity according to property resp. CB */
+	uint capacity;
+	switch (e->type) {
+		case VEH_TRAIN:    capacity = GetVehicleProperty(v, PROP_TRAIN_CARGO_CAPACITY,   e->u.rail.capacity); break;
+		case VEH_ROAD:     capacity = GetVehicleProperty(v, PROP_ROADVEH_CARGO_CAPACITY, e->u.road.capacity); break;
+		case VEH_SHIP:     capacity = GetVehicleProperty(v, PROP_SHIP_CARGO_CAPACITY,    e->u.ship.capacity); break;
+		case VEH_AIRCRAFT: capacity = e->u.air.passenger_capacity; break;
+		default: NOT_REACHED();
+	}
+
+	/* Apply multipliers depending on cargo- and vehicletype.
+	 * Note: This might change to become more consistent/flexible. */
+	if (e->type != VEH_SHIP) {
+		if (e->type == VEH_AIRCRAFT) {
+			if (v->cargo_type == CT_PASSENGERS) return capacity;
+			capacity += e->u.air.mail_capacity;
+			if (v->cargo_type == CT_MAIL) return capacity;
+		} else {
+			switch (default_cargo) {
+				case CT_PASSENGERS: break;
+				case CT_MAIL:
+				case CT_GOODS: capacity *= 2; break;
+				default:       capacity *= 4; break;
+			}
+		}
+		switch (v->cargo_type) {
+			case CT_PASSENGERS: break;
+			case CT_MAIL:
+			case CT_GOODS: capacity /= 2; break;
+			default:       capacity /= 4; break;
+		}
+	}
+
+	return capacity;
+}
+
 
 void Vehicle::BeginLoading()
 {