Function GrowTown

src/town_cmd.cpp:1897–1950

* Grow the town. * @param t The town to grow * @return true if we successfully grew the town with a road or house. */

 * @return true if we successfully grew the town with a road or house.
 */
static bool GrowTown(Town *t, TownExpandModes modes)
{
	static const TileIndexDiffC _town_coord_mod[] = {
		{-1,  0},
		{ 1,  1},
		{ 1, -1},
		{-1, -1},
		{-1,  0},
		{ 0,  2},
		{ 2,  0},
		{ 0, -2},
		{-1, -1},
		{-2,  2},
		{ 2,  2},
		{ 2, -2},
		{ 0,  0}
	};

	/* Current "company" is a town */
	Backup<CompanyID> cur_company(_current_company, OWNER_TOWN);

	TileIndex tile = t->xy; // The tile we are working with ATM

	/* Find a road that we can base the construction on. */
	for (const auto &ptr : _town_coord_mod) {
		if (GetTownRoadBits(tile) != ROAD_NONE) {
			bool success = GrowTownAtRoad(t, tile, modes);
			cur_company.Restore();
			return success;
		}
		tile = TileAdd(tile, ToTileIndexDiff(ptr));
	}

	/* No road available, try to build a random road block by
	 * clearing some land and then building a road there. */
	if (TownAllowedToBuildRoads(modes)) {
		tile = t->xy;
		for (const auto &ptr : _town_coord_mod) {
			/* Only work with plain land that not already has a house */
			if (!IsTileType(tile, MP_HOUSE) && IsTileFlat(tile)) {
				if (Command<CMD_LANDSCAPE_CLEAR>::Do({DoCommandFlag::Auto, DoCommandFlag::NoWater}, tile).Succeeded()) {
					RoadType rt = GetTownRoadType();
					Command<CMD_BUILD_ROAD>::Do({DoCommandFlag::Execute, DoCommandFlag::Auto}, tile, GenRandomRoadBits(), rt, DRD_NONE, t->index);
					cur_company.Restore();
					return true;
				}
			}
			tile = TileAdd(tile, ToTileIndexDiff(ptr));
		}
	}

	cur_company.Restore();
	return false;
}

/**
 * Update the cached town zone radii of a town, based on the number of houses.