public static CircularOrbitalPositionComponent CreateUnpoweredBody(Entity parent, double mass, double periodInDays, double meanAnomalyInDegrees, bool isPrograde, ICalendar calendar)
{
if (parent == null)
{
throw new ArgumentNullException(nameof(parent));
}
var parentMass = parent.GetRequiredComponent <OrbitalBodyCharacteristicsComponent>().Mass;
var mu = Constants.GravitationalConstant * (mass + parentMass);
var angularVelocity = (isPrograde ? 1 : -1) * 2.0 * Math.PI / (periodInDays * 24.0 * 3600.0);
var orbitalRadius = Math.Pow(mu / (angularVelocity * angularVelocity), 1.0 / 3.0);
var secondsFromEpoch = calendar.CreateTimePoint(2000, 1, 1).Tick *Constants.SecondsPerTick;
var initialAngle = (secondsFromEpoch * angularVelocity) + meanAnomalyInDegrees / (2.0 * Math.PI);
var relativePosition = new Point(orbitalRadius * Math.Cos(initialAngle), orbitalRadius * Math.Sin(initialAngle));
var angularVelocityPerTick = angularVelocity * Constants.SecondsPerTick;
return(new CircularOrbitalPositionComponent(parent.Id, relativePosition, angularVelocityPerTick, orbitalRadius));
}
