public Vector3d calculateVelocity(double timeEpoch, CelestialBody relativeTo, bool isFromDelta)
{
if (orbitalElements == null)
{
return(new Vector3d(0, 0, 0));
}
var eclipticVelocity = new Vector3d();
if (isFromDelta)
{
Vector3d pos1 = calculatePosition(timeEpoch);
Vector3d pos2 = calculatePosition(timeEpoch + 60);
eclipticVelocity = (pos2 - pos1) * (1.0 / 60.0);
}
else
{
//vis viva to calculate speed (not velocity, i.e not a vector)
OrbitalElementsPieces el = calculateElements(timeEpoch);
double speed = Math.Sqrt(SO.G * SO.U.getBody(relativeTo).mass *((2.0 / (el.r.Value)) - (1.0 / (el.a.Value))));
//now calculate velocity orientation, that is, a vector tangent to the orbital ellipse
double?k = el.r / el.a;
double?o = ((2 - (2 * el.e * el.e)) / (k * (2 - k))) - 1;
//floating point imprecision
o = o > 1 ? 1 : o;
double alpha = Math.PI - Math.Acos(o.Value);
alpha = el.v < 0 ? (2 * Math.PI) - alpha : alpha;
double velocityAngle = el.v.Value + (alpha / 2);
//velocity vector in the plane of the orbit
Vector3d orbitalVelocity = new Vector3d(Math.Cos(velocityAngle), Math.Sin(velocityAngle), 0).normalized *speed;
OrbitalElementsPieces velocityEls = el.Copy();
velocityEls.pos = orbitalVelocity;
velocityEls.v = 0;
velocityEls.r = 0;
eclipticVelocity = getPositionFromElements(velocityEls);
}
//var diff = eclipticVelocityFromDelta.sub(eclipticVelocity);console.log(diff.length());
return(eclipticVelocity);
}
public OrbitalElementsPieces calculateElements(double timeEpoch, OrbitalElementsPieces forcedOrbitalElements = null)
{
if (forcedOrbitalElements == null && this.orbitalElements == null)
{
return(null);
}
/* Debug.Log(this.name);
*
* Debug.Log(this.orbitalElements);
* Debug.Log(this.orbitalElements.cy);*/
OrbitalElementsPieces orbitalElements = forcedOrbitalElements ?? this.orbitalElements;
/*
*
* Epoch : J2000
*
* a Semi-major axis
* e Eccentricity
* i Inclination
* o Longitude of Ascending Node (Ω)
* w Argument of periapsis (ω)
* E Eccentric Anomaly
* T Time at perihelion
* M Mean anomaly
* l Mean Longitude
* lp longitude of periapsis
* r distance du centre
* v true anomaly
*
* P Sidereal period (mean value)
* Pw Argument of periapsis precession period (mean value)
* Pn Longitude of the ascending node precession period (mean value)
*
*/
if (epochCorrection.HasValue)
{
timeEpoch -= epochCorrection.Value;
}
double tDays = timeEpoch / SO.DAY;
double T = tDays / SO.CENTURY;
//console.log(T);
var computed = new OrbitalElementsPieces();
computed.t = timeEpoch;
if (calculator != null && forcedOrbitalElements == null)
{
OrbitalElementsPieces realorbit = calculator(T);
computed = realorbit.Copy();
}
else
{
if (orbitalElements.baseElements != null)
{
double variation = 0.0;
CalculateVariation(orbitalElements, orbitalElements.GetType().GetField("a"), computed, T);
CalculateVariation(orbitalElements, orbitalElements.GetType().GetField("e"), computed, T);
CalculateVariation(orbitalElements, orbitalElements.GetType().GetField("i"), computed, T);
CalculateVariation(orbitalElements, orbitalElements.GetType().GetField("l"), computed, T);
CalculateVariation(orbitalElements, orbitalElements.GetType().GetField("lp"), computed, T);
CalculateVariation(orbitalElements, orbitalElements.GetType().GetField("o"), computed, T);
CalculateVariation(orbitalElements, orbitalElements.GetType().GetField("E"), computed, T);
CalculateVariation(orbitalElements, orbitalElements.GetType().GetField("M"), computed, T);
CalculateVariation(orbitalElements, orbitalElements.GetType().GetField("r"), computed, T);
//CalculateVariation(orbitalElements, orbitalElements.GetType().GetField("t"), computed, T);
CalculateVariation(orbitalElements, orbitalElements.GetType().GetField("v"), computed, T);
CalculateVariation(orbitalElements, orbitalElements.GetType().GetField("w"), computed, T);
/*
* variation = orbitalElements.cy ? orbitalElements.cy[el] : (orbitalElements.day[el] * ns.CENTURY);
* variation = variation || 0;
* computed[el] = orbitalElements.base[el] + (variation * T);
*/
// Bomb
}
else
{
computed = orbitalElements.Copy();
}
if (!computed.w.HasValue)
{
computed.w = computed.lp - computed.o;
}
if (!computed.M.HasValue)
{
computed.M = computed.l - computed.lp;
}
computed.a = computed.a * SO.KM; //was in km, set it in m
}
computed.i = SO.DEG_TO_RAD * computed.i;
computed.o = SO.DEG_TO_RAD * computed.o;
computed.w = SO.DEG_TO_RAD * computed.w;
computed.M = SO.DEG_TO_RAD * computed.M;
computed.E = solveEccentricAnomaly(computed.e.Value, computed.M.Value);
computed.E = computed.E % SO.CIRCLE;
computed.i = computed.i % SO.CIRCLE;
computed.o = computed.o % SO.CIRCLE;
computed.w = computed.w % SO.CIRCLE;
computed.M = computed.M % SO.CIRCLE;
//in the plane of the orbit
computed.pos = new Vector3d((computed.a * (Math.Cos(computed.E.Value) - computed.e.Value)).Value,
(computed.a.Value * (Math.Sqrt(1 - (computed.e.Value * computed.e.Value))) * Math.Sin(computed.E.Value)));
computed.r = computed.pos.magnitude;
computed.v = Math.Atan2(computed.pos.y, computed.pos.x);
if (orbitalElements.relativeTo != null)
{
var relativeTo = SO.U.getBody(orbitalElements.relativeTo);
if (relativeTo.tilt.HasValue)
{
computed.tilt = -relativeTo.tilt.Value * SO.DEG_TO_RAD;
}
}
return(computed);
}
