/// <summary>
/// Sets the true anomaly and updates all other anomalies.
/// </summary>
/// <param name="t">The t.</param>
public void SetTrueAnomaly(double t)
{
if (!IsValidOrbit)
{
return;
}
t %= KeplerOrbitUtils.PI_2;
if (Eccentricity < 1)
{
if (t < 0)
{
t += KeplerOrbitUtils.PI_2;
}
EccentricAnomaly = KeplerOrbitUtils.ConvertTrueToEccentricAnomaly(t, Eccentricity);
MeanAnomaly = EccentricAnomaly - Eccentricity * Math.Sin(EccentricAnomaly);
}
else
{
EccentricAnomaly = KeplerOrbitUtils.ConvertTrueToEccentricAnomaly(t, Eccentricity);
MeanAnomaly = Math.Sinh(EccentricAnomaly) * Eccentricity - EccentricAnomaly;
}
SetPositionByCurrentAnomaly();
SetVelocityByCurrentAnomaly();
}
/// <summary>
/// Calculate eccentric anomaly in radians for point.
/// </summary>
/// <param name="point">Point in plane of elliptic shape.</param>
/// <returns>Eccentric anomaly radians.</returns>
public double GetEccentricAnomalyForPoint(Vector3d point)
{
var vector = point - Focus0;
var trueAnomaly = Vector3d.Angle(vector, AxisMain) * KeplerOrbitUtils.Deg2Rad;
if (KeplerOrbitUtils.DotProduct(vector, AxisSecondary) > 0)
{
trueAnomaly = KeplerOrbitUtils.PI_2 - trueAnomaly;
}
var result = KeplerOrbitUtils.ConvertTrueToEccentricAnomaly(trueAnomaly, Eccentricity);
return(result);
}
/// <summary>
/// Gets the central position at true anomaly.
/// </summary>
/// <param name="trueAnomaly">The true anomaly.</param>
/// <returns>Position relative to orbit center.</returns>
/// <remarks>
/// Note: central position is not same as focal position.
/// </remarks>
public Vector3d GetCentralPositionAtTrueAnomaly(double trueAnomaly)
{
double ecc = KeplerOrbitUtils.ConvertTrueToEccentricAnomaly(trueAnomaly, Eccentricity);
return(GetCentralPositionAtEccentricAnomaly(ecc));
}
/// <summary>
/// Calculates full orbit state from cartesian vectors: current body position, velocity, attractor mass, and gravConstant.
/// </summary>
public void CalculateOrbitStateFromOrbitalVectors()
{
MG = AttractorMass * GravConst;
AttractorDistance = Position.magnitude;
Vector3d angularMomentumVector = KeplerOrbitUtils.CrossProduct(Position, Velocity);
OrbitNormal = angularMomentumVector.normalized;
Vector3d eccVector;
if (OrbitNormal.sqrMagnitude < 0.99)
{
OrbitNormal = KeplerOrbitUtils.CrossProduct(Position, EclipticUp).normalized;
eccVector = new Vector3d();
}
else
{
eccVector = KeplerOrbitUtils.CrossProduct(Velocity, angularMomentumVector) / MG - Position / AttractorDistance;
}
OrbitNormalDotEclipticNormal = KeplerOrbitUtils.DotProduct(OrbitNormal, EclipticNormal);
FocalParameter = angularMomentumVector.sqrMagnitude / MG;
Eccentricity = eccVector.magnitude;
EnergyTotal = Velocity.sqrMagnitude - 2 * MG / AttractorDistance;
SemiMinorAxisBasis = KeplerOrbitUtils.CrossProduct(angularMomentumVector, -eccVector).normalized;
if (SemiMinorAxisBasis.sqrMagnitude < 0.99)
{
SemiMinorAxisBasis = KeplerOrbitUtils.CrossProduct(OrbitNormal, Position).normalized;
}
SemiMajorAxisBasis = KeplerOrbitUtils.CrossProduct(OrbitNormal, SemiMinorAxisBasis).normalized;
if (Eccentricity < 1)
{
OrbitCompressionRatio = 1 - Eccentricity * Eccentricity;
SemiMajorAxis = FocalParameter / OrbitCompressionRatio;
SemiMinorAxis = SemiMajorAxis * Math.Sqrt(OrbitCompressionRatio);
CenterPoint = -SemiMajorAxis * eccVector;
Period = KeplerOrbitUtils.PI_2 * Math.Sqrt(Math.Pow(SemiMajorAxis, 3) / MG);
Apoapsis = CenterPoint - SemiMajorAxisBasis * SemiMajorAxis;
Periapsis = CenterPoint + SemiMajorAxisBasis * SemiMajorAxis;
PeriapsisDistance = Periapsis.magnitude;
ApoapsisDistance = Apoapsis.magnitude;
TrueAnomaly = Vector3d.Angle(Position, SemiMajorAxisBasis) * KeplerOrbitUtils.Deg2Rad;
if (KeplerOrbitUtils.DotProduct(KeplerOrbitUtils.CrossProduct(Position, -SemiMajorAxisBasis), OrbitNormal) < 0)
{
TrueAnomaly = KeplerOrbitUtils.PI_2 - TrueAnomaly;
}
EccentricAnomaly = KeplerOrbitUtils.ConvertTrueToEccentricAnomaly(TrueAnomaly, Eccentricity);
MeanAnomaly = EccentricAnomaly - Eccentricity * Math.Sin(EccentricAnomaly);
}
else
{
OrbitCompressionRatio = Eccentricity * Eccentricity - 1;
SemiMajorAxis = FocalParameter / OrbitCompressionRatio;
SemiMinorAxis = SemiMajorAxis * Math.Sqrt(OrbitCompressionRatio);
CenterPoint = SemiMajorAxis * eccVector;
Period = double.PositiveInfinity;
Apoapsis = new Vector3d(double.PositiveInfinity, double.PositiveInfinity, double.PositiveInfinity);
Periapsis = CenterPoint - SemiMajorAxisBasis * (SemiMajorAxis);
PeriapsisDistance = Periapsis.magnitude;
ApoapsisDistance = double.PositiveInfinity;
TrueAnomaly = Vector3d.Angle(Position, eccVector) * KeplerOrbitUtils.Deg2Rad;
if (KeplerOrbitUtils.DotProduct(KeplerOrbitUtils.CrossProduct(Position, -SemiMajorAxisBasis), OrbitNormal) < 0)
{
TrueAnomaly = -TrueAnomaly;
}
EccentricAnomaly = KeplerOrbitUtils.ConvertTrueToEccentricAnomaly(TrueAnomaly, Eccentricity);
MeanAnomaly = Math.Sinh(EccentricAnomaly) * Eccentricity - EccentricAnomaly;
}
}
