// Move the stellar objects to their positions on the given date.
void System::SetDate(const Date &date)
{
double now = date.DaysSinceEpoch();
for(StellarObject &object : objects)
{
// "offset" is used to allow binary orbits; the second object is offset
// by 180 degrees.
object.angle = Angle(now * object.speed + object.offset);
object.position = object.angle.Unit() * object.distance;
// Because of the order of the vector, the parent's position has always
// been updated before this loop reaches any of its children, so:
if(object.parent >= 0)
object.position += objects[object.parent].position;
if(object.position)
object.angle = Angle(object.position);
if(object.planet)
object.planet->ResetDefense();
}
}
// Get the number of days between the two given dates.
int Date::operator-(const Date &other) const
{
return DaysSinceEpoch() - other.DaysSinceEpoch();
}
