private static Planet GeneratePlanet(PlanetSeed seed, int planetNo, ref Star sun, bool useRandomTilt, string planetID, bool isMoon, SystemGenerationOptions genOptions)
{
var planet = new Planet(seed, sun, planetNo);
planet.OrbitZone = Environment.OrbitalZone(sun.Luminosity, planet.SemiMajorAxisAU);
planet.OrbitalPeriodDays = Environment.Period(planet.SemiMajorAxisAU, planet.MassSM, sun.Mass);
if (useRandomTilt)
{
planet.AxialTiltDegrees = Environment.Inclination(planet.SemiMajorAxisAU);
}
planet.ExosphereTempKelvin = GlobalConstants.EARTH_EXOSPHERE_TEMP / Utilities.Pow2(planet.SemiMajorAxisAU / sun.EcosphereRadiusAU);
planet.RMSVelocityCMSec = Environment.RMSVelocity(GlobalConstants.MOL_NITROGEN, planet.ExosphereTempKelvin);
planet.CoreRadiusKM = Environment.KothariRadius(planet.DustMassSM, false, planet.OrbitZone);
// Calculate the radius as a gas giant, to verify it will retain gas.
// Then if mass > Earth, it's at least 5% gas and retains He, it's
// some flavor of gas giant.
planet.DensityGCC = Environment.EmpiricalDensity(planet.MassSM, planet.SemiMajorAxisAU, sun.EcosphereRadiusAU, true);
planet.RadiusKM = Environment.VolumeRadius(planet.MassSM, planet.DensityGCC);
planet.SurfaceAccelerationCMSec2 = Environment.Acceleration(planet.MassSM, planet.RadiusKM);
planet.SurfaceGravityG = Environment.Gravity(planet.SurfaceAccelerationCMSec2);
planet.MolecularWeightRetained = Environment.MinMolecularWeight(planet);
// Is the planet a gas giant?
if (((planet.MassSM * GlobalConstants.SUN_MASS_IN_EARTH_MASSES) > 1.0) && ((planet.GasMassSM / planet.MassSM) > 0.05) && (planet.MolecularWeightRetained <= 4.0))
{
if ((planet.GasMassSM / planet.MassSM) < 0.20)
{
planet.Type = PlanetType.SubSubGasGiant;
}
else if ((planet.MassSM * GlobalConstants.SUN_MASS_IN_EARTH_MASSES) < 20.0)
{
planet.Type = PlanetType.SubGasGiant;
}
else
{
planet.Type = PlanetType.GasGiant;
}
}
else // If not, it's rocky.
{
planet.RadiusKM = Environment.KothariRadius(planet.MassSM, false, planet.OrbitZone);
planet.DensityGCC = Environment.VolumeDensity(planet.MassSM, planet.RadiusKM);
planet.SurfaceAccelerationCMSec2 = Environment.Acceleration(planet.MassSM, planet.RadiusKM);
planet.SurfaceGravityG = Environment.Gravity(planet.SurfaceAccelerationCMSec2);
if ((planet.GasMassSM / planet.MassSM) > 0.000001)
{
var h2Mass = planet.GasMassSM * 0.85;
var heMass = (planet.GasMassSM - h2Mass) * 0.999;
var h2Life = Environment.GasLife(GlobalConstants.MOL_HYDROGEN, planet.ExosphereTempKelvin,
planet.SurfaceGravityG, planet.RadiusKM);
var heLife = Environment.GasLife(GlobalConstants.HELIUM, planet.ExosphereTempKelvin,
planet.SurfaceGravityG, planet.RadiusKM);
if (h2Life < sun.AgeYears)
{
var h2Loss = ((1.0 - (1.0 / Math.Exp(sun.AgeYears / h2Life))) * h2Mass);
planet.GasMassSM -= h2Loss;
planet.MassSM -= h2Loss;
planet.SurfaceAccelerationCMSec2 = Environment.Acceleration(planet.MassSM, planet.RadiusKM);
planet.SurfaceGravityG = Environment.Gravity(planet.SurfaceAccelerationCMSec2);
}
if (heLife < sun.AgeYears)
{
var heLoss = ((1.0 - (1.0 / Math.Exp(sun.AgeYears / heLife))) * heMass);
planet.GasMassSM -= heLoss;
planet.MassSM -= heLoss;
planet.SurfaceAccelerationCMSec2 = Environment.Acceleration(planet.MassSM, planet.RadiusKM);
planet.SurfaceGravityG = Environment.Gravity(planet.SurfaceAccelerationCMSec2);
}
}
}
planet.AngularVelocityRadSec = Environment.AngularVelocity(planet);
planet.DayLengthHours = Environment.DayLength(planet.AngularVelocityRadSec, planet.OrbitalPeriodDays,
planet.Eccentricity);
planet.HasResonantPeriod = Environment.HasResonantPeriod(planet.AngularVelocityRadSec,
planet.DayLengthHours, planet.OrbitalPeriodDays, planet.Eccentricity);
planet.EscapeVelocityCMSec = Environment.EscapeVelocity(planet.MassSM, planet.RadiusKM);
planet.HillSphereKM = Environment.SimplifiedHillSphereKM(sun.Mass, planet.MassSM, planet.SemiMajorAxisAU);
if (planet.IsGasGiant)
{
planet.HasGreenhouseEffect = false;
planet.VolatileGasInventory = GlobalConstants.INCREDIBLY_LARGE_NUMBER;
planet.Atmosphere.SurfacePressure = GlobalConstants.INCREDIBLY_LARGE_NUMBER;
planet.BoilingPointWaterKelvin = GlobalConstants.INCREDIBLY_LARGE_NUMBER;
planet.SurfaceTempKelvin = GlobalConstants.INCREDIBLY_LARGE_NUMBER;
planet.GreenhouseRiseKelvin = 0;
planet.Albedo = Utilities.About(GlobalConstants.GAS_GIANT_ALBEDO, 0.1);
planet.WaterCoverFraction = 1.0;
planet.CloudCoverFraction = 1.0;
planet.IceCoverFraction = 0.0;
planet.SurfaceGravityG = Environment.Gravity(planet.SurfaceAccelerationCMSec2);
planet.MolecularWeightRetained = Environment.MinMolecularWeight(planet);
planet.SurfaceGravityG = GlobalConstants.INCREDIBLY_LARGE_NUMBER;
}
else
{
planet.SurfaceGravityG = Environment.Gravity(planet.SurfaceAccelerationCMSec2);
planet.MolecularWeightRetained = Environment.MinMolecularWeight(planet);
planet.HasGreenhouseEffect = Environment.Greenhouse(sun.EcosphereRadiusAU, planet.SemiMajorAxisAU);
planet.VolatileGasInventory = Environment.VolatileInventory(
planet.MassSM, planet.EscapeVelocityCMSec, planet.RMSVelocityCMSec, sun.Mass,
planet.OrbitZone, planet.HasGreenhouseEffect, (planet.GasMassSM / planet.MassSM) > 0.000001);
planet.Atmosphere.SurfacePressure = Environment.Pressure(
planet.VolatileGasInventory, planet.RadiusKM, planet.SurfaceGravityG);
planet.BoilingPointWaterKelvin = Math.Abs(planet.Atmosphere.SurfacePressure) < 0.001
? 0.0
: Environment.BoilingPoint(planet.Atmosphere.SurfacePressure);
// Sets: planet.surf_temp, planet.greenhs_rise, planet.albedo, planet.hydrosphere,
// planet.cloud_cover, planet.ice_cover
Environment.IterateSurfaceTemp(ref planet);
CalculateGases(planet, genOptions.GasTable);
planet.IsTidallyLocked = Environment.IsTidallyLocked(planet);
// Assign planet type
if (planet.Atmosphere.SurfacePressure < 1.0)
{
if (!isMoon && ((planet.MassSM * GlobalConstants.SUN_MASS_IN_EARTH_MASSES) < GlobalConstants.ASTEROID_MASS_LIMIT))
{
planet.Type = PlanetType.Asteroids;
}
else
{
planet.Type = PlanetType.Barren;
}
}
else if ((planet.Atmosphere.SurfacePressure > 6000.0) && (planet.MolecularWeightRetained <= 2.0)) // Retains Hydrogen
{
planet.Type = PlanetType.SubSubGasGiant;
planet.Atmosphere.Composition = new List <Gas>();
}
else
{
// Atmospheres:
// TODO remove PlanetType enum entirely and replace it with a more flexible classification systme
if (planet.WaterCoverFraction >= 0.95) // >95% water
{
planet.Type = PlanetType.Water;
}
else if (planet.IceCoverFraction >= 0.95) // >95% ice
{
planet.Type = PlanetType.Ice;
}
else if (planet.WaterCoverFraction > 0.05) // Terrestrial
{
planet.Type = PlanetType.Terrestrial;
}
else if (planet.MaxTempKelvin > planet.BoilingPointWaterKelvin) // Hot = Venusian
{
planet.Type = PlanetType.Venusian;
}
else if ((planet.GasMassSM / planet.MassSM) > 0.0001) // Accreted gas, but no greenhouse or liquid water make it an ice world
{
planet.Type = PlanetType.Ice;
planet.IceCoverFraction = 1.0;
}
else if (planet.Atmosphere.SurfacePressure <= 250.0) // Thin air = Martian
{
planet.Type = PlanetType.Martian;
}
else if (planet.SurfaceTempKelvin < GlobalConstants.FREEZING_POINT_OF_WATER)
{
planet.Type = PlanetType.Ice;
}
else
{
planet.Type = PlanetType.Unknown;
}
}
}
// Generate moons
planet.Moons = new List <Planet>();
if (!isMoon)
{
var curMoon = seed.FirstMoon;
var n = 0;
while (curMoon != null)
{
if (curMoon.Mass * GlobalConstants.SUN_MASS_IN_EARTH_MASSES > .000001)
{
curMoon.SemiMajorAxisAU = planet.SemiMajorAxisAU;
curMoon.Eccentricity = planet.Eccentricity;
n++;
string moon_id = String.Format("{0}.{1}", planetID, n);
var generatedMoon = GeneratePlanet(curMoon, n, ref sun, useRandomTilt, moon_id, true, genOptions);
double roche_limit = 2.44 * planet.RadiusKM * Math.Pow((planet.DensityGCC / generatedMoon.DensityGCC), (1.0 / 3.0));
double hill_sphere = planet.SemiMajorAxisAU * GlobalConstants.KM_PER_AU * Math.Pow((planet.MassSM / (3.0 * sun.Mass)), (1.0 / 3.0));
if ((roche_limit * 3.0) < hill_sphere)
{
generatedMoon.MoonSemiMajorAxisAU = Utilities.RandomNumber(roche_limit * 1.5, hill_sphere / 2.0) / GlobalConstants.KM_PER_AU;
generatedMoon.MoonEccentricity = Utilities.RandomEccentricity();
}
else
{
generatedMoon.MoonSemiMajorAxisAU = 0;
generatedMoon.MoonEccentricity = 0;
}
planet.Moons.Add(generatedMoon);
}
curMoon = curMoon.NextPlanet;
}
}
return(planet);
}