Method GetDistance

src/cargopacket.h:220–253

* Get the current distance the cargo has traveled. * * @param current_tile Current tile of the cargo. * @return uint The distance (in tiles) traveled. */

	 * @return uint The distance (in tiles) traveled.
	 */
	inline uint GetDistance(TileIndex current_tile) const
	{
		assert(this->source_xy != INVALID_TILE);
#ifdef WITH_ASSERT
		assert(this->in_vehicle);
#endif /* WITH_ASSERT */

		/* Distance is always requested when the cargo is still inside the
		 * vehicle. So first finish the calculation for travelled to
		 * become a vector. */
		auto local_travelled = travelled;
		local_travelled.x -= TileX(current_tile);
		local_travelled.y -= TileY(current_tile);

		/* Cargo-movement is a vector that indicates how much the cargo has
		 * actually traveled in a vehicle. This is the distance you get paid
		 * for. However, one could construct a route where this vector would
		 * be really long. To not overpay the player, cap out at the distance
		 * between source and destination.
		 *
		 * This way of calculating is to counter people moving cargo for free
		 * and instantly in stations, where you deliver it in one part of the
		 * station and pick it up in another. By using the actual distance
		 * traveled in a vehicle, using this trick doesn't give you more money.
		 *
		 * However, especially in large networks with large transfer station,
		 * etc, one could actually make the route a lot longer. In that case,
		 * use the actual distance between source and destination.
		 */

		uint distance_travelled = abs(local_travelled.x) + abs(local_travelled.y);
		uint distance_source_dest = DistanceManhattan(this->source_xy, current_tile);
		return std::min(distance_travelled, distance_source_dest);
	}

	/**
	 * Gets the ID of station the cargo wants to go next.