public static OrbitingBodyMathematics generate_earth()
{
// from http://aa.usno.navy.mil/data/docs/EarthSeasons.php
var last_earth_perihelion = new DateTime(2016, 1, 2, 22, 49, 0);
// from http://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html
OrbitingBodyMathematics return_maths = new OrbitingBodyMathematics(
149.60, 0.01671022, last_earth_perihelion,
0.00005, -11.26064, 102.94719, 5.9726
);
// relative to the stars NOT to the sun
// from https://en.wikipedia.org/wiki/Earth%27s_rotation#Stellar_and_sidereal_day
double earth_rotation_period = 86164.098;
// Assumed/approximated
var last_earth_facing_the_sun
= new DateTime(2016, 11, 2, 12, 00, 00);
//Debug.Log("Last time facing the sun: " + last_earth_facing_the_sun);
Vector3 earth_position_when_facing_the_sun
= return_maths.current_location(last_earth_facing_the_sun);
DateTime last_time_facing_stellar_north
= CaclulateLastTimeFacingStellarNorth(
earth_rotation_period,
last_earth_facing_the_sun,
earth_position_when_facing_the_sun
);
return_maths.time_last_at_original_rotation = last_time_facing_stellar_north;
return_maths.rotation_period = earth_rotation_period;
return_maths.default_rotation_tilt_euler_angle
= new Vector3(-23.4f, 180.0f, 0);
return_maths.rotation_elements_set = true;
return(return_maths);
}
PositionTest(OrbitingBodyMathematics planet,
DateTime test_time,
double expected_longitude,
double expected_latitude,
double expected_distance)
{
string expected_string
= "\nExpected: longitude " + expected_longitude.ToString("F5")
+ " degrees, latitude " + expected_latitude.ToString("F5")
+ " degrees, distance " + expected_distance.ToString("F5")
+ " AU";
Vector3 coordinates = planet.current_location(test_time);
Vector3 longlatdist = planet.current_longlatdist(test_time);
Console.Write(coordinates.ToString("E"));
Console.Write(longlatdist.ToString("F5"));
double longitude_error = Math.Abs(longlatdist.x - expected_longitude);
double acceptable_longitude_error = 0.05;
string longitude_error_message = differing_results_error_message(
Convert.ToString(longlatdist.x),
Convert.ToString(expected_longitude),
"degrees"
);
double latitude_error = Math.Abs(longlatdist.y - expected_latitude);
double acceptable_latitude_error = 0.01;
string latitude_error_message = differing_results_error_message(
Convert.ToString(longlatdist.y),
Convert.ToString(expected_latitude),
"degrees"
);
double distance_error = Math.Abs(longlatdist.z - expected_distance);
double acceptable_distance_error = 0.00001;
string distance_error_message = differing_results_error_message(
Convert.ToString(longlatdist.z),
Convert.ToString(expected_distance),
"AU"
);
Debug.Log(
"Longitude Error: " + longitude_error + " degrees, "
+ "Latitude Error: " + latitude_error + " degrees, "
+ "Distance Error: " + distance_error + " AU"
);
Assert.LessOrEqual(longitude_error, acceptable_longitude_error,
"Longitude Error: " + longitude_error_message + expected_string);
Assert.LessOrEqual(latitude_error, acceptable_latitude_error,
"Latitude Error: " + latitude_error_message + expected_string);
Assert.LessOrEqual(distance_error, acceptable_distance_error,
"Distance Error: " + distance_error_message + expected_string);
}
RotationRelativeToSunTest(double expected_angle,
DateTime test_time,
OrbitingBodyMathematics planet)
{
Vector3 planet_position
= planet.current_location(test_time);
Debug.Log("Planet position 3D: " + planet_position.ToString());
Vector2 planet_position_2d
= new Vector2(planet_position.x, planet_position.y);
double rotation_progress
= planet.current_stellar_day_rotation_progress(test_time);
Debug.Log("Rotation progress: " + rotation_progress);
Debug.Log("Anti-clockwise angle = " + (rotation_progress * 360.0));
float angle_from_up = (float)rotation_progress * 2 * Mathf.PI;
// angle is anti-clockwise due to earth's/solar system's rotation
Vector2 rotation
= new Vector2(Mathf.Sin(angle_from_up), Mathf.Cos(angle_from_up));
Vector2 planet_normalised = planet_position_2d / planet_position_2d.magnitude;
Vector2 rotation_normalised = rotation / rotation.magnitude;
Debug.Log("Planet vector: " + planet_normalised.ToString());
Debug.Log("Rotation vector: " + rotation_normalised.ToString());
double actual_angle
= Vector2.Angle(planet_normalised, rotation_normalised);
double acceptable_error = 0.1;
double actual_error
= Math.Abs(actual_angle
- expected_angle);
string error_message = differing_results_error_message(
Convert.ToString(actual_angle),
Convert.ToString(expected_angle),
"degrees"
);
Assert.LessOrEqual(actual_error, acceptable_error, error_message);
}
