std::string to_string( const time_point &p )
{
const int year = to_turns<int>( p - calendar::time_of_cataclysm ) / to_turns<int>
( calendar::year_length() ) + 1;
const std::string time = to_string_time_of_day( p );
if( calendar::eternal_season() ) {
const int day = to_days<int>( time_past_new_year( p ) );
//~ 1 is the year, 2 is the day (of the *year*), 3 is the time of the day in its usual format
return string_format( _( "Year %1$d, day %2$d %3$s" ), year, day, time );
} else {
const int day = day_of_season<int>( p );
//~ 1 is the year, 2 is the season name, 3 is the day (of the season), 4 is the time of the day in its usual format
return string_format( _( "Year %1$d, %2$s, day %3$d %4$s" ), year,
calendar::name_season( season_of_year( p ) ), day, time );
}
}
w_point weather_generator::get_weather( const tripoint &location, const time_point &t,
unsigned seed ) const
{
const double x( location.x /
2000.0 ); // Integer x position / widening factor of the Perlin function.
const double y( location.y /
2000.0 ); // Integer y position / widening factor of the Perlin function.
const double z( to_turn<int>( t + calendar::season_length() ) /
2000.0 ); // Integer turn / widening factor of the Perlin function.
const double dayFraction = time_past_midnight( t ) / 1_days;
//limit the random seed during noise calculation, a large value flattens the noise generator to zero
//Windows has a rand limit of 32768, other operating systems can have higher limits
const unsigned modSEED = seed % 32768;
// Noise factors
double T( raw_noise_4d( x, y, z, modSEED ) * 4.0 );
double H( raw_noise_4d( x, y, z / 5, modSEED + 101 ) );
double H2( raw_noise_4d( x, y, z, modSEED + 151 ) / 4 );
double P( raw_noise_4d( x, y, z / 3, modSEED + 211 ) * 70 );
double A( raw_noise_4d( x, y, z, modSEED ) * 8.0 );
double W;
const double now( ( time_past_new_year( t ) + calendar::season_length() / 2 ) /
calendar::year_length() ); // [0,1)
const double ctn( cos( tau * now ) );
// Temperature variation
const double mod_t( 0 ); // TODO: make this depend on latitude and altitude?
const double current_t( base_temperature +
mod_t ); // Current baseline temperature. Degrees Celsius.
const double seasonal_variation( ctn * -1 ); // Start and end at -1 going up to 1 in summer.
const double season_atenuation( ctn / 2 + 1 ); // Harsh winter nights, hot summers.
const double season_dispersion( pow( 2,
ctn + 1 ) - 2.3 ); // Make summers peak faster and winters not perma-frozen.
const double daily_variation( cos( tau * dayFraction - tau / 8 ) * -1 * season_atenuation / 2 +
season_dispersion * -1 ); // Day-night temperature variation.
T += current_t; // Add baseline to the noise.
T += seasonal_variation * 8 * exp( -pow( current_t * 2.7 / 10 - 0.5,
2 ) ); // Add season curve offset to account for the winter-summer difference in day-night difference.
T += daily_variation * 8 * exp( -pow( current_t / 30,
2 ) ); // Add daily variation scaled to the inverse of the current baseline. A very specific and finicky adjustment curve.
T = T * 9 / 5 + 32; // Convert to imperial. =|
// Humidity variation
const double mod_h( 0 );
const double current_h( base_humidity + mod_h );
H = std::max( std::min( ( ctn / 10.0 + ( -pow( H, 2 ) * 3 + H2 ) ) * current_h / 2.0 + current_h,
100.0 ),
0.0 ); // Humidity stays mostly at the mean level, but has low peaks rarely. It's a percentage.
// Pressure variation
P += seasonal_variation * 20 +
base_pressure; // Pressure is mostly random, but a bit higher on summer and lower on winter. In millibars.
// Wind power
W = std::max( 0, 1020 - static_cast<int>( P ) );
// Acid rains
const double acid_content = base_acid * A;
bool acid = acid_content >= 1.0;
return w_point {T, H, P, W, acid};
}
