boost/geometry/algorithms/intersection.hpp

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// Boost.Geometry (aka GGL, Generic Geometry Library)
//
// Copyright Barend Gehrels 2007-2009, Geodan, Amsterdam, the Netherlands.
// Copyright Bruno Lalande 2008, 2009
// Use, modification and distribution is subject to the Boost Software License,
// Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)

#ifndef BOOST_GEOMETRY_ALGORITHMS_INTERSECTION_HPP
#define BOOST_GEOMETRY_ALGORITHMS_INTERSECTION_HPP


#include <boost/mpl/if.hpp>

#include <boost/geometry/core/reverse_dispatch.hpp>
#include <boost/geometry/geometries/concepts/check.hpp>
#include <boost/geometry/algorithms/overlay/clip_linestring.hpp>
#include <boost/geometry/algorithms/overlay/assemble.hpp>



namespace boost { namespace geometry
{


#ifndef DOXYGEN_NO_DETAIL
namespace detail { namespace overlay {



// Specializations for "take_one" for intersection
// "one" should be the inner one

// for ring and box
template
<
    typename Tag1, typename Geometry1,
    typename Tag2, typename Geometry2,
    typename GeometryOut
>
struct take_if_1_is_in_2<Tag1, Geometry1, Tag2, Geometry2, GeometryOut, -1>
{
    static inline void apply(Geometry1 const& geometry1,
                Geometry2 const& geometry2,
                GeometryOut& out
                )
    {
        geometry::convert(geometry1, out);
    }
};


template
<
    typename Geometry1,
    typename Tag2, typename Geometry2,
    typename GeometryOut
>
struct take_if_1_is_in_2<polygon_tag, Geometry1, Tag2, Geometry2, GeometryOut, -1>
{
    static inline void apply(Geometry1 const& geometry1,
                Geometry2 const& geometry2,
                GeometryOut& out
                )
    {
        geometry::convert(exterior_ring(geometry1), out);
    }
};


template
<
    typename Geometry, typename GeometryOut, typename Container
>
struct add_holes<polygon_tag, Geometry, GeometryOut, Container, -1>
{

    static inline void apply(Geometry const& geometry,
                GeometryOut& out,
                Container const& holes
                )
    {
        std::vector<sortable> v;
        sort_interior_rings(holes, v, -1);

        // For an intersection, if a ring is containing an inner ring,
        // take the outer

        std::size_t const n = boost::size(v);

        for (std::size_t i = 0; i < n; i++)
        {
            // So, only if no inners:
            if (v[i].index_of_parent == -1)
            {
                typename geometry::point_type<GeometryOut>::type point;
                geometry::point_on_border(holes[v[i].index], point);
                if (geometry::within(point, geometry))
                {
                    typename ring_type<GeometryOut>::type hole;
                    geometry::convert(holes[v[i].index], hole);
                    geometry::interior_rings(out).push_back(hole);
                }
            }
        }
    }
};


}} // namespace detail::overlay
#endif // DOXYGEN_NO_DETAIL


#ifndef DOXYGEN_NO_DISPATCH
namespace dispatch
{

template
<
    typename Tag1, typename Tag2, typename Tag3,
    typename G1, typename G2,
    typename OutputIterator,
    typename GeometryOut,
    typename Strategy
>
struct intersection_inserter
    : detail::overlay::overlay_and_assemble
        <G1, G2, OutputIterator, GeometryOut, -1, Strategy>
{};


template
<
    typename Segment1, typename Segment2,
    typename OutputIterator, typename GeometryOut,
    typename Strategy
>
struct intersection_inserter
    <
        segment_tag, segment_tag, point_tag,
        Segment1, Segment2,
        OutputIterator, GeometryOut,
        Strategy
    >
{
    static inline OutputIterator apply(Segment1 const& segment1,
            Segment2 const& segment2, OutputIterator out, Strategy const& strategy)
    {
        typedef typename point_type<GeometryOut>::type point_type;

        // Get the intersection point (or two points)
        segment_intersection_points<point_type> is
            = strategy::intersection::relate_cartesian_segments
            <
                policies::relate::segments_intersection_points
                    <
                        Segment1,
                        Segment2,
                        segment_intersection_points<point_type>
                    >
            >::apply(segment1, segment2);

        for (std::size_t i = 0; i < is.count; i++)
        {
            GeometryOut p;
            geometry::copy_coordinates(is.intersections[i], p);
            *out = p;
            out++;
        }
        return out;
    }
};


template
<
    typename Linestring, typename Box,
    typename OutputIterator, typename GeometryOut,
    typename Strategy
>
struct intersection_inserter
    <
        linestring_tag, box_tag, linestring_tag,
        Linestring, Box,
        OutputIterator, GeometryOut,
        Strategy
    >
{
    static inline OutputIterator apply(Linestring const& linestring,
            Box const& box, OutputIterator out, Strategy const& strategy)
    {
        typedef typename point_type<GeometryOut>::type point_type;
        strategy::intersection::liang_barsky<Box, point_type> lb_strategy;
        return detail::intersection::clip_linestring_with_box<GeometryOut>(box, linestring, out, lb_strategy);
    }
};


template
<
    typename GeometryTag1, typename GeometryTag2, typename GeometryTag3,
    typename Geometry1, typename Geometry2,
    typename OutputIterator, typename GeometryOut,
    typename Strategy
>
struct intersection_inserter_reversed
{
    static inline OutputIterator apply(Geometry1 const& g1,
                Geometry2 const& g2, OutputIterator out,
                Strategy const& strategy)
    {
        return intersection_inserter
            <
                GeometryTag2, GeometryTag1, GeometryTag3,
                Geometry2, Geometry1,
                OutputIterator, GeometryOut,
                Strategy
            >::apply(g2, g1, out, strategy);
    }
};



} // namespace dispatch
#endif // DOXYGEN_NO_DISPATCH

template
<
    typename GeometryOut,
    typename Geometry1,
    typename Geometry2,
    typename OutputIterator,
    typename Strategy
>
inline OutputIterator intersection_inserter(Geometry1 const& geometry1,
            Geometry2 const& geometry2,
            OutputIterator out,
            Strategy const& strategy)
{
    concept::check<const Geometry1>();
    concept::check<const Geometry2>();

    return boost::mpl::if_c
        <
            reverse_dispatch<Geometry1, Geometry2>::type::value,
            dispatch::intersection_inserter_reversed
            <
                typename tag<Geometry1>::type,
                typename tag<Geometry2>::type,
                typename tag<GeometryOut>::type,
                Geometry1,
                Geometry2,
                OutputIterator, GeometryOut,
                Strategy
            >,
            dispatch::intersection_inserter
            <
                typename tag<Geometry1>::type,
                typename tag<Geometry2>::type,
                typename tag<GeometryOut>::type,
                Geometry1,
                Geometry2,
                OutputIterator, GeometryOut,
                Strategy
            >
        >::type::apply(geometry1, geometry2, out, strategy);
}


template
<
    typename GeometryOut,
    typename Geometry1,
    typename Geometry2,
    typename OutputIterator
>
inline OutputIterator intersection_inserter(Geometry1 const& geometry1,
            Geometry2 const& geometry2,
            OutputIterator out)
{
    concept::check<const Geometry1>();
    concept::check<const Geometry2>();

    typedef typename geometry::point_type<GeometryOut>::type point_type;
    typedef detail::intersection::intersection_point<point_type> ip_type;

    typedef strategy_intersection
        <
            typename cs_tag<point_type>::type,
            Geometry1,
            Geometry2,
            ip_type
        > strategy;

    return intersection_inserter<GeometryOut>(geometry1, geometry2, out, strategy());
}


}} // namespace boost::geometry


#endif //GGL_ALGORITHMS_INTERSECTION_HPP

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December 1, 2009

Copyright © 1995-2009 Barend Gehrels, Geodan, Amsterdam Copyright © 2008-2009 Bruno Lalande, Paris Copyright © 2009 Mateusz Loskot, Cadcorp, London