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-rw-r--r--src/station_cmd.cpp100
1 files changed, 61 insertions, 39 deletions
diff --git a/src/station_cmd.cpp b/src/station_cmd.cpp
index 8085af255..4f1c5363c 100644
--- a/src/station_cmd.cpp
+++ b/src/station_cmd.cpp
@@ -1751,6 +1751,32 @@ static const byte * const _airport_sections[] = {
_airport_sections_helistation // Helistation
};
+/**
+ * Computes the minimal distance from town's xy to any airport's tile.
+ * @param afc airport's description
+ * @param town_tile town's tile (t->xy)
+ * @param airport_tile st->airport_tile
+ * @return minimal manhattan distance from town_tile to any airport's tile
+ */
+static uint GetMinimalAirportDistanceToTile(const AirportFTAClass *afc, TileIndex town_tile, TileIndex airport_tile)
+{
+ uint ttx = TileX(town_tile); // X, Y of town
+ uint tty = TileY(town_tile);
+
+ uint atx = TileX(airport_tile); // X, Y of northern airport corner
+ uint aty = TileY(airport_tile);
+
+ uint btx = TileX(airport_tile) + afc->size_x - 1; // X, Y of southern corner
+ uint bty = TileY(airport_tile) + afc->size_y - 1;
+
+ /* if ttx < atx, dx = atx - ttx
+ * if atx <= ttx <= btx, dx = 0
+ * else, dx = ttx - btx (similiar for dy) */
+ uint dx = ttx < atx ? atx - ttx : (ttx <= btx ? 0 : ttx - btx);
+ uint dy = tty < aty ? aty - tty : (tty <= bty ? 0 : tty - bty);
+
+ return dx + dy;
+}
/** Get a possible noise reduction factor based on distance from town center.
* The further you get, the less noise you generate.
@@ -1762,44 +1788,11 @@ static const byte * const _airport_sections[] = {
*/
uint8 GetAirportNoiseLevelForTown(const AirportFTAClass *afc, TileIndex town_tile, TileIndex tile)
{
- struct TileIndexDistance {
- TileIndex index;
- 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 (afc->noise_level < 2) return afc->noise_level;
- uint distance;
-
- /* Find the airport-to-be's closest corner to the town */
- if (afc->size_x == 1 && afc->size_y == 1) {
- distance = DistanceManhattan(town_tile, tile); // ont tile, one corner, it's THE corner
- } else {
- /* calculate manhattan distance to town of each side of the airport */
- TileIndexDistance dist[4]; ///< Array that will contain all 4 corners in TileIndex and distance
- uint min_tile = UINT_MAX; ///< Sentinel value
- uint min_indice = 4;
-
- /* Based on the size of the airport, establish location of each corner*/
- dist[0].index = tile; // north tile
- dist[1].index = TileAddWrap(tile, afc->size_x - 1, afc->size_y - 1); // south tile
- dist[2].index = TileAddWrap(tile, afc->size_x - 1, 0); // west tile
- dist[3].index = TileAddWrap(tile, 0, afc->size_y - 1); //east tile
-
- /* now, go and find the smallest one, thus the closest to town */
- for (uint i = 0; i < 4; i++) {
- dist[i].distance = DistanceManhattan(town_tile, dist[i].index);
-
- if (dist[i].distance < min_tile) {
- min_tile = dist[i].distance; // here's a new candidate
- min_indice = i;
- }
- }
-
- distance = dist[min_indice].distance;
- }
+ uint distance = GetMinimalAirportDistanceToTile(afc, town_tile, tile);
/* 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.
@@ -1816,6 +1809,31 @@ uint8 GetAirportNoiseLevelForTown(const AirportFTAClass *afc, TileIndex town_til
return noise_reduction >= afc->noise_level ? 1 : afc->noise_level - noise_reduction;
}
+/**
+ * Finds the town nearest to given airport. Based on minimal manhattan distance to any airport's tile.
+ * If two towns have the same distance, town with lower index is returned.
+ * @param afc airport's description
+ * @param airport_tile st->airport_tile
+ * @return nearest town to airport
+ */
+Town *AirportGetNearestTown(const AirportFTAClass *afc, TileIndex airport_tile)
+{
+ Town *t, *nearest = NULL;
+ uint add = afc->size_x + afc->size_y - 2; // GetMinimalAirportDistanceToTile can differ from DistanceManhattan by this much
+ uint mindist = UINT_MAX - add; // prevent overflow
+ FOR_ALL_TOWNS(t) {
+ if (DistanceManhattan(t->xy, airport_tile) < mindist + add) { // avoid calling GetMinimalAirportDistanceToTile too often
+ uint dist = GetMinimalAirportDistanceToTile(afc, t->xy, airport_tile);
+ if (dist < mindist) {
+ nearest = t;
+ mindist = dist;
+ }
+ }
+ }
+
+ return nearest;
+}
+
/** Recalculate the noise generated by the airports of each town */
void UpdateAirportsNoise()
@@ -1827,7 +1845,9 @@ void UpdateAirportsNoise()
FOR_ALL_STATIONS(st) {
if (st->airport_tile != INVALID_TILE) {
- st->town->noise_reached += GetAirportNoiseLevelForTown(GetAirport(st->airport_type), st->town->xy, st->airport_tile);
+ const AirportFTAClass *afc = GetAirport(st->airport_type);
+ Town *nearest = AirportGetNearestTown(afc, st->airport_tile);
+ nearest->noise_reached += GetAirportNoiseLevelForTown(afc, nearest->xy, st->airport_tile);
}
}
}
@@ -1871,14 +1891,15 @@ CommandCost CmdBuildAirport(TileIndex tile, uint32 flags, uint32 p1, uint32 p2,
if (CmdFailed(cost)) return cost;
/* Go get the final noise level, that is base noise minus factor from distance to town center */
- uint newnoise_level = GetAirportNoiseLevelForTown(afc, t->xy, tile);
+ Town *nearest = AirportGetNearestTown(afc, tile);
+ uint newnoise_level = GetAirportNoiseLevelForTown(afc, nearest->xy, tile);
/* Check if local auth would allow a new airport */
bool authority_refused;
if (_settings_game.economy.station_noise_level) {
/* do not allow to build a new airport if this raise the town noise over the maximum allowed by town */
- authority_refused = (t->noise_reached + newnoise_level) > t->MaxTownNoise();
+ authority_refused = (nearest->noise_reached + newnoise_level) > nearest->MaxTownNoise();
} else {
uint num = 0;
const Station *st;
@@ -1939,7 +1960,7 @@ CommandCost CmdBuildAirport(TileIndex tile, uint32 flags, uint32 p1, uint32 p2,
if (flags & DC_EXEC) {
/* Always add the noise, so there will be no need to recalculate when option toggles */
- st->town->noise_reached += newnoise_level;
+ nearest->noise_reached += newnoise_level;
st->airport_tile = tile;
st->AddFacility(FACIL_AIRPORT, tile);
@@ -2020,7 +2041,8 @@ static CommandCost RemoveAirport(Station *st, uint32 flags)
/* Go get the final noise level, that is base noise minus factor from distance to town center.
* And as for construction, always remove it, even if the patch is not set, in order to avoid the
* need of recalculation */
- st->town->noise_reached -= GetAirportNoiseLevelForTown(afc, st->town->xy, tile);
+ Town *nearest = AirportGetNearestTown(afc, tile);
+ nearest->noise_reached -= GetAirportNoiseLevelForTown(afc, nearest->xy, tile);
st->rect.AfterRemoveRect(st, tile, w, h);