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// Example of using the GeographicLib::GeodesicLine class
#include <iostream>
#include <iomanip>
#include <exception>
#include <cmath>
#include <GeographicLib/Geodesic.hpp>
#include <GeographicLib/GeodesicLine.hpp>
#include <GeographicLib/Constants.hpp>
using namespace std;
using namespace GeographicLib;
int main() {
try {
// Print waypoints between JFK and SIN
Geodesic geod(Constants::WGS84_a(), Constants::WGS84_f());
// Alternatively: const Geodesic& geod = Geodesic::WGS84();
double
lat1 = 40.640, lon1 = -73.779, // JFK
lat2 = 1.359, lon2 = 103.989; // SIN
GeodesicLine line = geod.InverseLine(lat1, lon1, lat2, lon2);
double ds0 = 500e3; // Nominal distance between points = 500 km
int num = int(ceil(line.Distance() / ds0)); // The number of intervals
cout << fixed << setprecision(3);
{
// Use intervals of equal length
double ds = line.Distance() / num;
for (int i = 0; i <= num; ++i) {
double lat, lon;
line.Position(i * ds, lat, lon);
cout << i << " " << lat << " " << lon << "\n";
}
}
{
// Slightly faster, use intervals of equal arc length
double da = line.Arc() / num;
for (int i = 0; i <= num; ++i) {
double lat, lon;
line.ArcPosition(i * da, lat, lon);
cout << i << " " << lat << " " << lon << "\n";
}
}
{
// Check that the inspection functions for exact = true return the same
// as for GeodesicLineExact.
Geodesic geoda(6.4e6, 0.5, true);
GeodesicExact geodb(6.4e6, 0.5);
GeodesicLine linea = geoda.InverseLine(lat1, lon1, lat2, lon2);
GeodesicLineExact lineb = geodb.InverseLine(lat1, lon1, lat2, lon2);
if (! (linea.Init() == lineb.Init() &&
linea.Latitude() == lineb.Latitude() &&
linea.Longitude() == lineb.Longitude() &&
linea.Azimuth() == lineb.Azimuth() &&
linea.EquatorialAzimuth() == lineb.EquatorialAzimuth() &&
linea.EquatorialArc() == lineb.EquatorialArc() &&
linea.EquatorialRadius() == lineb.EquatorialRadius() &&
linea.Flattening() == lineb.Flattening() &&
linea.Capabilities() == lineb.Capabilities() &&
linea.Distance() == lineb.Distance() &&
linea.Arc() == lineb.Arc()) )
cerr << "Incompatible results compared to GeodesicLineExact\n";
}
}
catch (const exception& e) {
cerr << "Caught exception: " << e.what() << "\n";
return 1;
}
}
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