94 lines
3.3 KiB
Rust
94 lines
3.3 KiB
Rust
//! Tests for the frame carrying position types.
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use apsis_coord::{EarthRotationAngle, Ecef, Eci, Geodetic, WGS84};
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use apsis_math::Vec3;
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const EPS: f64 = 1e-9;
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#[test]
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fn constructors_round_trip_the_vector() {
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let vector = Vec3::new(1.0, 2.0, 3.0);
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assert_eq!(Eci::new(vector).vector(), vector);
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assert_eq!(Ecef::new(vector).vector(), vector);
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}
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#[test]
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fn geodetic_fields_round_trip() {
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let position = Geodetic::new(0.5, -1.0, 250.0);
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assert_eq!(position.latitude(), 0.5);
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assert_eq!(position.longitude(), -1.0);
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assert_eq!(position.height(), 250.0);
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assert_eq!(position.ellipsoidal().latitude, 0.5);
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}
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#[test]
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fn geodetic_to_ecef_uses_wgs84_by_default() {
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let position = Geodetic::new(0.35, -1.2, 123.0);
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assert_eq!(position.to_ecef(), position.to_ecef_on(WGS84));
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}
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#[test]
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fn geodetic_to_ecef_and_back_round_trips() {
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let original = Geodetic::new(0.921, -1.234, 12_345.0);
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let recovered = original
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.to_ecef()
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.to_geodetic(WGS84)
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.expect("off-axis points have a longitude");
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assert!((recovered.latitude() - original.latitude()).abs() < 1e-11);
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assert!((recovered.longitude() - original.longitude()).abs() < 1e-11);
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assert!((recovered.height() - original.height()).abs() < 1e-4);
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}
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#[test]
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fn polar_axis_has_no_defined_longitude() {
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let on_axis = Ecef::new(Vec3::new(0.0, 0.0, WGS84.semi_minor_axis()));
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assert_eq!(on_axis.to_geodetic(WGS84), None);
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assert_eq!(Ecef::new(Vec3::ZERO).to_geodetic(WGS84), None);
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}
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#[test]
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fn frame_conversions_round_trip() {
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let angle = EarthRotationAngle::from_ut1_days(9.25);
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let original = Eci::new(Vec3::new(7_000.0, -1_500.0, 3_200.0));
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let ecef = original.to_ecef(angle);
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let back = ecef.to_eci(angle);
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assert!((back.vector() - original.vector()).norm() < EPS);
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}
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#[test]
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fn frame_conversion_preserves_length() {
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let angle = EarthRotationAngle::from_ut1_days(-3.5);
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let vector = Vec3::new(6_878_137.0, 0.0, 0.0);
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let converted = Eci::new(vector).to_ecef(angle);
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assert!((converted.vector().norm() - vector.norm()).abs() < 1e-6);
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}
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#[test]
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fn a_ground_point_rotates_with_the_earth() {
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// A point on the equator at zero longitude in the Earth-fixed frame is
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// rotated by the Earth Rotation Angle in the inertial frame.
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let angle = EarthRotationAngle::from_ut1_days(1.5);
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let ground = Ecef::new(Vec3::new(6_378_137.0, 0.0, 0.0));
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let inertial = ground.to_eci(angle);
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let radians = angle.radians_positive();
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let expected = Vec3::new(
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6_378_137.0 * radians.cos(),
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6_378_137.0 * radians.sin(),
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0.0,
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);
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assert!((inertial.vector() - expected).norm() < 1e-6);
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}
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#[test]
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fn a_geodetic_station_round_trips_through_both_frames() {
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// A station is fixed to the ground, so converting it to the inertial
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// frame and back at the same angle returns the original position.
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let station = Geodetic::new(0.662, 0.175, 80.0);
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let angle = EarthRotationAngle::from_ut1_julian_date(2_460_000.5);
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let inertial = station.to_ecef().to_eci(angle);
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let back = inertial.to_ecef(angle).to_geodetic(WGS84).expect("station");
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assert!((back.latitude() - station.latitude()).abs() < 1e-11);
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assert!((back.longitude() - station.longitude()).abs() < 1e-11);
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assert!((back.height() - station.height()).abs() < 1e-4);
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}
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