Function UpdateNearestTownForRoadTiles

src/road_cmd.cpp:1944–1958

* Updates cached nearest town for all road tiles * @param invalidate are we just invalidating cached data? * @pre invalidate == true implies _generating_world == true */

 * @pre invalidate == true implies _generating_world == true
 */
void UpdateNearestTownForRoadTiles(bool invalidate)
{
	assert(!invalidate || _generating_world);

	for (const auto t : Map::Iterate()) {
		if (IsTileType(t, MP_ROAD) && !IsRoadDepot(t) && !HasTownOwnedRoad(t)) {
			TownID tid = TownID::Invalid();
			if (!invalidate) {
				const Town *town = CalcClosestTownFromTile(t);
				if (town != nullptr) tid = town->index;
			}
			SetTownIndex(t, tid);
		}
	}
}

static int GetSlopePixelZ_Road(TileIndex tile, uint x, uint y, bool)
{