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// Example of using the GeographicLib::PolygonArea class
#include <iostream>
#include <exception>
#include <GeographicLib/PolygonArea.hpp>
#include <GeographicLib/Geodesic.hpp>
#include <GeographicLib/Constants.hpp>
using namespace std;
using namespace GeographicLib;
int main() {
try {
Geodesic geod(Constants::WGS84_a(), Constants::WGS84_f());
// Alternatively: const Geodesic& geod = Geodesic::WGS84();
PolygonArea poly(geod);
poly.AddPoint( 52, 0); // London
poly.AddPoint( 41,-74); // New York
poly.AddPoint(-23,-43); // Rio de Janeiro
poly.AddPoint(-26, 28); // Johannesburg
double perimeter, area;
unsigned n = poly.Compute(false, true, perimeter, area);
cout << n << " " << perimeter << " " << area << "\n";
// This adds a test for a bug fix for AddEdge. (Implements the
// Planimeter29 test in geodtest.c.)
PolygonArea poly1(geod);
poly1.AddPoint(0,0);
poly1.AddEdge(90,1000);
poly1.AddEdge(0,1000);
poly1.AddEdge(-90,1000);
n = poly1.Compute(false, true, perimeter, area);
// The area should be 1e6. Prior to the fix it was 1e6 - A/2, where
// A = ellipsoid area.
cout << n << " " << perimeter << " " << area << "\n";
}
catch (const exception& e) {
cerr << "Caught exception: " << e.what() << "\n";
return 1;
}
}
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