Function GetAirportNoiseLevelForDistance

src/station_cmd.cpp:2523–2542

* Get a possible noise reduction factor based on distance from town center. * The further you get, the less noise you generate. * So all those folks at city council can now happily slee... work in their offices * @param as airport information * @param distance minimum distance between town and airport * @return the noise that will be generated, according to distance */

 * @return the noise that will be generated, according to distance
 */
uint8_t GetAirportNoiseLevelForDistance(const AirportSpec *as, uint distance)
{
	/* 0 cannot be accounted, and 1 is the lowest that can be reduced from town.
	 * So no need to go any further*/
	if (as->noise_level < 2) return as->noise_level;

	/* The steps for measuring noise reduction are based on the "magical" (and arbitrary) 8 base distance
	 * adding the town_council_tolerance 4 times, as a way to graduate, depending of the tolerance.
	 * Basically, it says that the less tolerant a town is, the bigger the distance before
	 * an actual decrease can be granted */
	uint8_t town_tolerance_distance = 8 + (_settings_game.difficulty.town_council_tolerance * 4);

	/* now, we want to have the distance segmented using the distance judged bareable by town
	 * This will give us the coefficient of reduction the distance provides. */
	uint noise_reduction = distance / town_tolerance_distance;

	/* If the noise reduction equals the airport noise itself, don't give it for free.
	 * Otherwise, simply reduce the airport's level. */
	return noise_reduction >= as->noise_level ? 1 : as->noise_level - noise_reduction;
}

/**
 * Finds the town nearest to given airport. Based on minimal manhattan distance to any airport's tile.