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Codechange: Use KDTree for AirportGetNearestTown (#7424)

This commit is contained in:
SamuXarick 2019-12-24 17:37:30 +00:00 committed by Charles Pigott
parent c7ead8388c
commit 40605efd1c
1 changed files with 18 additions and 24 deletions
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42
src/station_cmd.cpp
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@ -2129,23 +2129,6 @@ CommandCost CmdRemoveRoadStop(TileIndex tile, DoCommandFlag flags, uint32 p1, ui
return had_success ? cost : last_error;
}
/**
* Computes the minimal distance from town's xy to any airport's tile.
* @param it An iterator over all airport tiles.
* @param town_tile town's tile (t->xy)
* @return minimal manhattan distance from town_tile to any airport's tile
*/
static uint GetMinimalAirportDistanceToTile(TileIterator &it, TileIndex town_tile)
{
uint mindist = UINT_MAX;
for (TileIndex cur_tile = it; cur_tile != INVALID_TILE; cur_tile = ++it) {
mindist = min(mindist, DistanceManhattan(town_tile, cur_tile));
}
return mindist;
}
/**
* Get a possible noise reduction factor based on distance from town center.
* The further you get, the less noise you generate.
@ -2185,14 +2168,25 @@ uint8 GetAirportNoiseLevelForDistance(const AirportSpec *as, uint distance)
*/
Town *AirportGetNearestTown(const AirportSpec *as, const TileIterator &it, uint &mindist)
{
assert(Town::GetNumItems() > 0);
Town *nearest = nullptr;
uint add = as->size_x + as->size_y - 2; // GetMinimalAirportDistanceToTile can differ from DistanceManhattan by this much
mindist = UINT_MAX - add; // prevent overflow
for (Town *t : Town::Iterate()) {
if (DistanceManhattan(t->xy, it) < mindist + add) { // avoid calling GetMinimalAirportDistanceToTile too often
TileIterator *copy = it.Clone();
uint dist = GetMinimalAirportDistanceToTile(*copy, t->xy);
delete copy;
uint perimeter_min_x = TileX(it);
uint perimeter_min_y = TileY(it);
uint perimeter_max_x = perimeter_min_x + as->size_x - 1;
uint perimeter_max_y = perimeter_min_y + as->size_y - 1;
mindist = UINT_MAX - 1; // prevent overflow
std::unique_ptr<TileIterator> copy(it.Clone());
for (TileIndex cur_tile = *copy; cur_tile != INVALID_TILE; cur_tile = ++*copy) {
if (TileX(cur_tile) == perimeter_min_x || TileX(cur_tile) == perimeter_max_x || TileY(cur_tile) == perimeter_min_y || TileY(cur_tile) == perimeter_max_y) {
Town *t = CalcClosestTownFromTile(cur_tile, mindist + 1);
if (t == nullptr) continue;
uint dist = DistanceManhattan(t->xy, cur_tile);
if (dist == mindist && t->index < nearest->index) nearest = t;
if (dist < mindist) {
nearest = t;
mindist = dist;