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88 lines
2.2 KiB
C++
88 lines
2.2 KiB
C++
// Boost.Geometry (aka GGL, Generic Geometry Library)
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// QuickBook Example
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// Copyright (c) 2011 Barend Gehrels, Amsterdam, the Netherlands.
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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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//[difference_inserter
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//` Shows how the difference_inserter function can be used
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#include <iostream>
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#include <vector>
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#include <boost/geometry/geometry.hpp>
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#include <boost/geometry/geometries/geometries.hpp>
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#include <boost/geometry/domains/gis/io/wkt/wkt.hpp>
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#include <boost/foreach.hpp>
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/*<-*/ #include "create_svg_overlay.hpp" /*->*/
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int main()
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{
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typedef boost::geometry::model::polygon<boost::geometry::model::d2::point_xy<double> > polygon;
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polygon green, blue;
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boost::geometry::read_wkt(
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"POLYGON((2 1.3,2.4 1.7,2.8 1.8,3.4 1.2,3.7 1.6,3.4 2,4.1 3,5.3 2.6,5.4 1.2,4.9 0.8,2.9 0.7,2 1.3)"
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"(4.0 2.0, 4.2 1.4, 4.8 1.9, 4.4 2.2, 4.0 2.0))", green);
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boost::geometry::read_wkt(
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"POLYGON((4.0 -0.5 , 3.5 1.0 , 2.0 1.5 , 3.5 2.0 , 4.0 3.5 , 4.5 2.0 , 6.0 1.5 , 4.5 1.0 , 4.0 -0.5))", blue);
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std::vector<polygon> output;
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// Note that this sample simulates the symmetric difference,
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// which is also available as a separate algorithm.
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// It chains the output iterator returned by the function to the second instance.
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boost::geometry::difference_inserter<polygon>
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(
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green, blue,
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boost::geometry::difference_inserter<polygon>
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(
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blue, green,
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std::back_inserter(output)
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)
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);
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int i = 0;
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std::cout << "(blue \ green) u (green \ blue):" << std::endl;
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BOOST_FOREACH(polygon const& p, output)
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{
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std::cout << i++ << ": " << boost::geometry::area(p) << std::endl;
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}
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/*<-*/ create_svg("difference_inserter.svg", green, blue, output); /*->*/
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return 0;
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}
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//]
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//[difference_inserter_output
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/*`
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Output:
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[pre
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(blue \\ green) u (green \\ blue):
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0: 0.525154
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1: 0.015
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2: 0.181136
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3: 0.128798
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4: 0.340083
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5: 0.307778
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6: 0.02375
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7: 0.542951
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8: 0.0149697
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9: 0.226855
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10: 0.839424
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[$img/algorithms/sym_difference.png]
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]
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*/
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//]
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