Function FindNearestGoodCoastalTownSpot

src/town_cmd.cpp:2337–2360

* Given a spot on the map (presumed to be a water tile), find a good * coastal spot to build a city. We don't want to build too close to * the edge if we can help it (since that inhibits city growth) hence * the search within a search within a search. O(n*m^2), where n is * how far to search for land, and m is how far inland to look for a * flat spot. * * @param tile Start looking from this

 * @return tile that was found
 */
static TileIndex FindNearestGoodCoastalTownSpot(TileIndex tile, TownLayout layout)
{
	for (auto coast : SpiralTileSequence(tile, 40)) {
		/* Find nearest land tile */
		if (!IsTileType(coast, MP_CLEAR)) continue;

		TileIndex furthest = INVALID_TILE;
		uint max_dist = 0;
		for (auto test : SpiralTileSequence(coast, 10)) {
			if (!IsTileType(test, MP_CLEAR) || !IsTileFlat(test) || !IsTileAlignedToGrid(test, layout)) continue;
			if (TownCanBePlacedHere(test, true).Failed()) continue;

			uint dist = GetClosestWaterDistance(test, true);
			if (dist > max_dist) {
				furthest = test;
				max_dist = dist;
			}
		}
		return furthest;
	}

	/* if we get here just give up */
	return INVALID_TILE;
}

/**
 * Get the HouseZones climate mask for the current landscape type.