DistanceFunction.hpp

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#pragma once
#include <fishnet/IGeometry.hpp>
#include <fishnet/WGS84Ellipsoid.hpp>
 
struct WGS84Distance{
    static auto operator()(const fishnet::geometry::Vec2DReal & lhs, const fishnet::geometry::Vec2DReal & rhs) noexcept {
        return fishnet::WGS84Ellipsoid::distance(lhs,rhs);
    }
};
 
struct MetricDistance{
    static auto operator()(const fishnet::geometry::Vec2DReal & lhs, const fishnet::geometry::Vec2DReal & rhs) noexcept {
        return lhs.distance(rhs);
    }
};
 
using DistanceFunction = std::function<fishnet::math::DEFAULT_FLOATING_POINT(const fishnet::geometry::Vec2DReal &, const fishnet::geometry::Vec2DReal &)>;
 
static DistanceFunction distanceFunctionForSpatialReference(const OGRSpatialReference & spatialRef) {
    if(spatialRef.IsEmpty())
        throw std::runtime_error("No distance function available for empty coordinate system");
    if(spatialRef.IsLocal() || spatialRef.IsProjected())
        return MetricDistance();
    if(spatialRef.IsGeographic())
        return WGS84Distance();
    throw std::runtime_error("No distance function found for coordinate system: \""+std::string(spatialRef.GetName())+"\"");
}