Function UpdateTownRadius

src/town_cmd.cpp:1956–1997

* Update the cached town zone radii of a town, based on the number of houses. * @param t The town to update. */

 * @param t The town to update.
 */
void UpdateTownRadius(Town *t)
{
	static const std::array<std::array<uint32_t, NUM_HOUSE_ZONES>, 23> _town_squared_town_zone_radius_data = {{
		{  4,  0,  0,  0,  0}, // 0
		{ 16,  0,  0,  0,  0},
		{ 25,  0,  0,  0,  0},
		{ 36,  0,  0,  0,  0},
		{ 49,  0,  4,  0,  0},
		{ 64,  0,  4,  0,  0}, // 20
		{ 64,  0,  9,  0,  1},
		{ 64,  0,  9,  0,  4},
		{ 64,  0, 16,  0,  4},
		{ 81,  0, 16,  0,  4},
		{ 81,  0, 16,  0,  4}, // 40
		{ 81,  0, 25,  0,  9},
		{ 81, 36, 25,  0,  9},
		{ 81, 36, 25, 16,  9},
		{ 81, 49,  0, 25,  9},
		{ 81, 64,  0, 25,  9}, // 60
		{ 81, 64,  0, 36,  9},
		{ 81, 64,  0, 36, 16},
		{100, 81,  0, 49, 16},
		{100, 81,  0, 49, 25},
		{121, 81,  0, 49, 25}, // 80
		{121, 81,  0, 49, 25},
		{121, 81,  0, 49, 36}, // 88
	}};

	if (t->cache.num_houses < std::size(_town_squared_town_zone_radius_data) * 4) {
		t->cache.squared_town_zone_radius = _town_squared_town_zone_radius_data[t->cache.num_houses / 4];
	} else {
		int mass = t->cache.num_houses / 8;
		/* Actually we are proportional to sqrt() but that's right because we are covering an area.
		 * The offsets are to make sure the radii do not decrease in size when going from the table
		 * to the calculated value.*/
		t->cache.squared_town_zone_radius[to_underlying(HouseZone::TownEdge)] = mass * 15 - 40;
		t->cache.squared_town_zone_radius[to_underlying(HouseZone::TownOutskirt)] = mass * 9 - 15;
		t->cache.squared_town_zone_radius[to_underlying(HouseZone::TownOuterSuburb)] = 0;
		t->cache.squared_town_zone_radius[to_underlying(HouseZone::TownInnerSuburb)] = mass * 5 - 5;
		t->cache.squared_town_zone_radius[to_underlying(HouseZone::TownCentre)] = mass * 3 + 5;
	}
}

/**
 * Update the maximum amount of monthly passengers and mail for a town, based on its population.