private static DateTimeOffset entryDateAround(PlanetId star, Sign destSign, DateTimeOffset around)
{
Double speed = Planet.AverageSpeedOf(star);
int dayAdjustment = 0;
DateTimeOffset date = around.UtcDateTime.Date;
Position pos = CurrentEphemeris[date, star];
int dif = destSign.Order - Sign.SignOf(pos.Longitude).Order;
dayAdjustment = dif > 0 ? (int)((destSign.Order - Sign.SignOf(pos.Longitude).Order - 1) * 30 / speed)
: (int)((11 + destSign.Order - Sign.SignOf(pos.Longitude).Order) * 30 / speed);
do
{
date = date.AddDays(dayAdjustment);
pos = CurrentEphemeris[date, star];
dayAdjustment--;
} while (Sign.SignOf(pos.Longitude) != destSign.Previous);
if (Sign.SignOf(pos.Longitude) != destSign.Previous)
{
throw new Exception();
}
do
{
date = date.AddDays(1);
pos = CurrentEphemeris[date, star];
if (Sign.SignOf(pos.Longitude) == destSign)
{
return(date);
}
} while (true);
throw new Exception();
}
public DateTimeOffset ExactlyTimeOf(PlanetId id, DateTimeOffset refDate, Rectascension destination)
{
double jul_ut = Utilities.ToJulianDay(refDate);
double averageSpeed = Planet.AverageSpeedOf(id);
Position posAverage, posDynamic = PositionDelegate(jul_ut, id);
double shiftDynamic, shiftAverage;
double dest = destination.Degrees;
double distanceDynamic = Angle.BeelineOf(posDynamic.Longitude, dest);
if (distanceDynamic < 0)
{
distanceDynamic += 360;
}
double lastDistance = 360, lastShift, distanceAverage = distanceDynamic;
shiftDynamic = distanceDynamic / (posDynamic.LongitudeVelocity < 0 ? averageSpeed : posDynamic.LongitudeVelocity);
shiftAverage = distanceAverage / averageSpeed;
for (int i = 0; i < 10; i++)
{
posDynamic = PositionDelegate(jul_ut + shiftDynamic, id);
posAverage = PositionDelegate(jul_ut + shiftAverage, id);
distanceDynamic = Angle.BeelineOf(posDynamic.Longitude, dest);
distanceAverage = Angle.BeelineOf(posAverage.Longitude, dest);
if (Math.Abs(distanceAverage) > Math.Abs(distanceDynamic))
{
if (Math.Abs(distanceDynamic) < Negligible)
{
return(Utilities.UtcFromJulianDay(jul_ut));
}
jul_ut += shiftDynamic;
lastShift = shiftDynamic;
distanceAverage = distanceDynamic;
posAverage = posDynamic;
lastDistance = distanceDynamic;
}
else
{
if (Math.Abs(distanceAverage) < Negligible)
{
return(Utilities.UtcFromJulianDay(jul_ut));
}
jul_ut += shiftAverage;
lastShift = shiftAverage;
distanceDynamic = distanceAverage;
posDynamic = posAverage;
lastDistance = distanceAverage;
}
shiftDynamic = distanceDynamic / posDynamic.LongitudeVelocity;
shiftAverage = distanceAverage / averageSpeed;
}
throw new Exception("Failed destination get the exact time!");
}