coordinate_systems_example.cpp

Coordinate systems and frame transform walkthrough.

Coordinate systems and frame transform walkthrough.Usage: cmake –build build-make –target coordinate_systems_example ./build-make/coordinate_systems_example

 
#include <siderust/siderust.hpp>
 
#include <cstdio>
 
using namespace siderust;
using namespace siderust::frames;
using namespace qtty::literals;
 
int main() {
    std::printf("=== Coordinate Systems Example ===\n\n");
 
    auto obs = ROQUE_DE_LOS_MUCHACHOS;
    auto jd  = JulianDate::from_utc({2026, 7, 15, 22, 0, 0});
 
    std::printf("Observer (Geodetic): lon=%.4f deg lat=%.4f deg h=%.1f m\n",
                obs.lon.value(), obs.lat.value(), obs.height.value());
 
    auto ecef_m  = obs.to_cartesian<qtty::Meter>();
    auto ecef_km = obs.to_cartesian<qtty::Kilometer>();
    std::printf("Observer (ECEF): x=%.2f m y=%.2f m z=%.2f m\n",
                ecef_m.x().value(), ecef_m.y().value(), ecef_m.z().value());
    std::printf("Observer (ECEF): x=%.2f km y=%.2f km z=%.2f km\n\n",
                ecef_km.x().value(), ecef_km.y().value(), ecef_km.z().value());
 
    // Vega J2000 ICRS direction.
    spherical::direction::ICRS vega_icrs(279.23473, 38.78369);
 
    auto vega_ecl    = vega_icrs.to<EclipticMeanJ2000>(jd);
    auto vega_eq_mod = vega_icrs.to<EquatorialMeanOfDate>(jd);
    auto vega_eq_tod = vega_icrs.to<EquatorialTrueOfDate>(jd);
    auto vega_hor    = vega_icrs.to_horizontal(jd, obs);
    auto vega_back   = vega_ecl.to<ICRS>(jd);
 
    std::printf("Vega ICRS: RA=%.6f Dec=%.6f\n",
                vega_icrs.ra().value(), vega_icrs.dec().value());
    std::printf("Vega EclipticMeanJ2000: lon=%.6f lat=%.6f\n",
                vega_ecl.lon().value(), vega_ecl.lat().value());
    std::printf("Vega EquatorialMeanOfDate: RA=%.6f Dec=%.6f\n",
                vega_eq_mod.ra().value(), vega_eq_mod.dec().value());
    std::printf("Vega EquatorialTrueOfDate: RA=%.6f Dec=%.6f\n",
                vega_eq_tod.ra().value(), vega_eq_tod.dec().value());
    std::printf("Vega Horizontal: az=%.6f alt=%.6f\n",
                vega_hor.az().value(), vega_hor.alt().value());
    std::printf("Vega roundtrip ICRS<-Ecliptic: RA=%.6f Dec=%.6f\n\n",
                vega_back.ra().value(), vega_back.dec().value());
 
    spherical::position::ICRS<qtty::AstronomicalUnit> target_sph_au(
        120.0_deg, -25.0_deg, 2.0_au);
    auto target_dir = target_sph_au.direction();
    std::printf("Spherical ICRS position: RA=%.2f Dec=%.2f dist=%.3f AU\n",
                target_sph_au.ra().value(),
                target_sph_au.dec().value(),
                target_sph_au.distance().value());
    std::printf("Direction extracted from spherical position: RA=%.2f Dec=%.2f\n\n",
                target_dir.ra().value(), target_dir.dec().value());
 
    cartesian::position::ICRS<qtty::Meter>            target_cart_m(1.5e11, -3.0e10, 2.0e10);
    cartesian::position::ICRS<qtty::AstronomicalUnit> target_cart_au(
        target_cart_m.x().to<qtty::AstronomicalUnit>(),
        target_cart_m.y().to<qtty::AstronomicalUnit>(),
        target_cart_m.z().to<qtty::AstronomicalUnit>());
 
    std::printf("Cartesian ICRS position: x=%.3e m y=%.3e m z=%.3e m\n",
                target_cart_m.x().value(),
                target_cart_m.y().value(),
                target_cart_m.z().value());
    std::printf("Cartesian ICRS position: x=%.6f AU y=%.6f AU z=%.6f AU\n",
                target_cart_au.x().value(),
                target_cart_au.y().value(),
                target_cart_au.z().value());
 
    return 0;
}