//The mean anomaly of the orbit.
//For elliptical orbits, the value return is always between 0 and 2pi
//For hyperbolic orbits, the value can be any number.
internal static double MeanAnomalyAtUT(this Orbit o, double UT)
{
double ret = o.meanAnomalyAtEpoch + o.MeanMotion() * (UT - o.epoch);
if (o.eccentricity < 1)
{
ret = MuUtils.ClampRadiansTwoPi(ret);
}
return(ret);
}
//The next time at which the orbiting object will reach the given mean anomaly.
//For elliptical orbits, this will be a time between UT and UT + o.period
//For hyperbolic orbits, this can be any time, including a time in the past, if
//the given mean anomaly occurred in the past
internal static double UTAtMeanAnomaly(this Orbit o, double meanAnomaly, double UT)
{
double currentMeanAnomaly = o.MeanAnomalyAtUT(UT);
double meanDifference = meanAnomaly - currentMeanAnomaly;
if (o.eccentricity < 1)
{
meanDifference = MuUtils.ClampRadiansTwoPi(meanDifference);
}
return(UT + meanDifference / o.MeanMotion());
}
//Originally by Zool, revised by The_Duck
//Converts an eccentric anomaly into a mean anomaly.
//For an elliptical orbit, the returned value is between 0 and 2pi
//For a hyperbolic orbit, the returned value is any number
internal static double GetMeanAnomalyAtEccentricAnomaly(this Orbit o, double E)
{
double e = o.eccentricity;
if (e < 1) //elliptical orbits
{
return(MuUtils.ClampRadiansTwoPi(E - (e * Math.Sin(E))));
}
else //hyperbolic orbits
{
return((e * Math.Sinh(E)) - E);
}
}
//Returns whether o has a descending node with the equator. This can be false
//if o is hyperbolic and the would-be descending node is within the opening
//angle of the hyperbola.
internal static bool DescendingNodeEquatorialExists(this Orbit o)
{
return(Math.Abs(MuUtils.ClampDegrees180(o.DescendingNodeEquatorialTrueAnomaly())) <= o.MaximumTrueAnomaly());
}
//Returns whether a has a descending node with b. This can be false
//if a is hyperbolic and the would-be descending node is within the opening
//angle of the hyperbola.
internal static bool DescendingNodeExists(this Orbit a, Orbit b)
{
return(Math.Abs(MuUtils.ClampDegrees180(a.DescendingNodeTrueAnomaly(b))) <= a.MaximumTrueAnomaly());
}
//Gives the true anomaly at which o crosses the equator going southwards, if o is east-moving,
//or northwards, if o is west-moving.
//The returned value is always between 0 and 360.
internal static double DescendingNodeEquatorialTrueAnomaly(this Orbit o)
{
return(MuUtils.ClampDegrees360(o.AscendingNodeEquatorialTrueAnomaly() + 180));
}
//Gives the true anomaly (in a's orbit) at which a crosses its descending node
//with b's orbit.
//The returned value is always between 0 and 360.
internal static double DescendingNodeTrueAnomaly(this Orbit a, Orbit b)
{
return(MuUtils.ClampDegrees360(a.AscendingNodeTrueAnomaly(b) + 180));
}
