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65 lines
2.6 KiB
C++
65 lines
2.6 KiB
C++
// Boost.Geometry (aka GGL, Generic Geometry Library)
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//
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// Copyright (c) 2007-2012 Barend Gehrels, Amsterdam, the Netherlands.
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// Copyright (c) 2008-2012 Bruno Lalande, Paris, France.
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// Use, modification and distribution is subject to the Boost Software License,
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// Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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//
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// Projection example 2, using factory
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#include <boost/geometry.hpp>
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#include <boost/geometry/geometries/point_xy.hpp>
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#include <boost/geometry/extensions/gis/latlong/latlong.hpp>
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#include <boost/geometry/extensions/gis/projections/parameters.hpp>
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#include <boost/geometry/extensions/gis/projections/factory.hpp>
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#include <boost/shared_ptr.hpp>
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int main()
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{
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using namespace boost::geometry;
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// Initialize projection parameters. For construction using a factory the projection name is required.
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projections::parameters par = projections::init("+proj=robin +ellps=WGS84 +units=m");
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// Construct the specified projection, using specified point types
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// Note that this is the only difference from p01_projection_example. It constructs a projection
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// with virtual methods, which can be used polymorphically. Therefore it is a pointer. For
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// convenience we use a boost shared pointer here.
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typedef model::ll::point<degree> point_ll_deg;
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typedef model::d2::point_xy<double> point_xy;
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projections::factory<point_ll_deg, point_xy> fac;
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boost::shared_ptr<projections::projection<point_ll_deg, point_xy> > prj(fac.create_new(par));
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// Define Amsterdam / Barcelona in decimal degrees / degrees/minutes
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point_ll_deg amsterdam(longitude<>(5.9), latitude<>(52.4));
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point_ll_deg barcelona(
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latitude<>(dms<north>(41, 23)),
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longitude<>(dms<east>(2, 11))
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);
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point_xy pa, pb;
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// Do the forward projection
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if (prj->forward(amsterdam, pa) && prj->forward(barcelona, pb))
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{
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std::cout << "Amsterdam: " << wkt(pa) << std::endl << "Barcelona: " << wkt(pb) << std::endl;
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std::cout << "Distance (unprojected):" << distance(amsterdam, barcelona) / 1000.0 << " km" << std::endl;
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std::cout << "Distance ( projected):" << distance(pa, pb) / 1000.0 << " km" << std::endl;
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// Get the inverse
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point_ll_deg a1;
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if (prj->inverse(pa, a1))
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{
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std::cout << "Amsterdam (original): " << wkt(amsterdam) << std::endl
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<< "Amsterdam (projected, and back):" << wkt(a1) << std::endl;
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std::cout << "Distance a-a': " << distance(amsterdam, a1) << " meter" << std::endl;
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}
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}
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return 0;
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}
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