int bfs(const vector<vector<int>> &grid, const int r, const int c) {
bool visited[128][128];
memset(visited, 0, sizeof(visited));
point_t q[128*128];
int q_beg = 0, q_end = 1;
q[0] = point_t(r, c);
visited[r][c] = true;
const int roffs[] = { -1, 0, 1, 0 };
const int coffs[] = { 0, 1, 0, -1 };
int cnt = 0;
while (q_beg != q_end) {
point_t pnt = q[q_beg++];
for (int i = 0; i < 4; i++) {
int roff = roffs[i];
int coff = coffs[i];
int newr = pnt.first + roff;
int newc = pnt.second + coff;
if (!is_land(grid, newr, newc)) {
cnt++;
} else {
if (visited[newr][newc])
continue;
visited[newr][newc] = true;
q[q_end++] = point_t(newr, newc);
}
}
}
return cnt;
}
void _iterate_humidity (const Planet& planet, const Climate_parameters& par, Climate_generation_season& season) {
std::deque<float> humidity;
std::deque<float> precipitation;
humidity.resize(tile_count(planet));
precipitation.resize(tile_count(planet));
float delta = 1.0;
while (delta > par.error_tolerance) {
// std::cout << "delta: " << delta << "\n";
for (int i=0; i<tile_count(planet); i++) {
precipitation[i] = 0.0;
if (is_land(nth_tile(terrain(planet), i))) {
humidity[i] = 0.0;
precipitation[i] = 0.0;
float incoming_wind = _incoming_wind(planet, season, i);
float outgoing_wind = _outgoing_wind(planet, season, i);
if (incoming_wind > 0.0) {
float convection = outgoing_wind - incoming_wind;
float incoming_humidity = _incoming_humidity(planet, season, i);
// less humidity when incoming wind is less than outgoing
float density = convection > 0 ?
incoming_humidity / (incoming_wind + convection) :
incoming_humidity / incoming_wind;
float saturation = saturation_humidity(season.tiles[i].temperature);
// limit to saturation humidity
humidity[i] = std::min(saturation, density);
if (saturation < density)
precipitation[i] += (density - saturation) * incoming_wind;
// increase humidity when outgoing wind is less than incoming
if (convection < 0) {
float convective = humidity[i] * (-convection / incoming_wind);
if (humidity[i] + convective > saturation)
precipitation[i] += (humidity[i] + convective - saturation) * (-convection);
humidity[i] = std::min(saturation, humidity[i] + convective);
}
}
// scale by constant and area
precipitation[i] *= 3.0 / area(planet, nth_tile(planet, i));
}
else
humidity[i] = season.tiles[i].humidity;
}
float largest_change = 0.0;
for (int i=0; i<tile_count(planet); i++) {
largest_change = std::max(largest_change, _humidity_change(season.tiles[i].humidity, humidity[i]));
}
delta = largest_change;
for (int i=0; i<tile_count(planet); i++) {
season.tiles[i].humidity = humidity[i];
season.tiles[i].precipitation = precipitation[i];
}
}
}
void _set_temperature (const Planet& planet, const Climate_parameters&, Climate_generation_season& season) {
auto temperature_at_latitude = [](float latitude) {
return freezing_point() - 25 + 50*cos(latitude);
};
for (auto& t : tiles(planet)) {
float temperature = temperature_at_latitude(season.tropical_equator - latitude(planet, vector(t)));
if (is_land(nth_tile(terrain(planet), id(t)))) {
if (elevation(nth_tile(terrain(planet), id(t))) > sea_level(planet))
temperature -= temperature_lapse(elevation(nth_tile(terrain(planet), id(t))) - sea_level(planet));
}
else {
temperature = 0.3*temperature + 0.7*temperature_at_latitude(latitude(planet, vector(t)));
}
season.tiles[id(t)].temperature = temperature;
}
}
Wind _default_wind (const Planet& p, int i, double tropical_equator) {
Vector2 pressure_force = _default_pressure_gradient_force(tropical_equator, latitude(p, vector(nth_tile(p,i))));
double coriolis_coeff = coriolis_coefficient(p, latitude(p, vector(nth_tile(p,i))));
double friction = is_land(nth_tile(terrain(p), i)) ? 0.000045 : 0.000045;
return _prevailing_wind(pressure_force, coriolis_coeff, friction);
}
