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+// Boost.Geometry (aka GGL, Generic Geometry Library)
+
+// Copyright (c) 2007-2014 Barend Gehrels, Amsterdam, the Netherlands.
+
+// 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_GEOMETRY_POLICIES_RELATE_INTERSECTION_RATIOS_HPP
+#define BOOST_GEOMETRY_GEOMETRY_POLICIES_RELATE_INTERSECTION_RATIOS_HPP
+
+
+#include <algorithm>
+#include <string>
+
+#include <boost/concept_check.hpp>
+#include <boost/numeric/conversion/cast.hpp>
+
+#include <boost/geometry/algorithms/detail/assign_indexed_point.hpp>
+#include <boost/geometry/core/access.hpp>
+#include <boost/geometry/strategies/side_info.hpp>
+
+
+namespace boost { namespace geometry
+{
+
+namespace policies { namespace relate
+{
+
+
+/*!
+\brief Policy returning segment ratios
+\note Template argument FractionType should be a fraction_type<SegmentRatio>
+ */
+template
+<
+ typename FractionType
+>
+struct segments_intersection_ratios
+{
+ typedef FractionType return_type;
+
+ template
+ <
+ typename Segment1,
+ typename Segment2,
+ typename SegmentIntersectionInfo
+ >
+ static inline return_type segments_crosses(side_info const&,
+ SegmentIntersectionInfo const& sinfo,
+ Segment1 const& , Segment2 const& )
+ {
+ return_type result;
+ result.assign(sinfo);
+ return result;
+ }
+
+ template <typename Segment1, typename Segment2, typename Ratio>
+ static inline return_type segments_collinear(
+ Segment1 const& , Segment2 const& ,
+ Ratio const& ra_from_wrt_b, Ratio const& ra_to_wrt_b,
+ Ratio const& rb_from_wrt_a, Ratio const& rb_to_wrt_a)
+ {
+ // We have only one result, for (potentially) two IP's,
+ // so we take a first one
+ return_type result;
+
+ if (ra_from_wrt_b.on_segment())
+ {
+ result.assign(Ratio::zero(), ra_from_wrt_b);
+ }
+ else if (rb_from_wrt_a.in_segment())
+ {
+ result.assign(rb_from_wrt_a, Ratio::zero());
+ }
+ else if (ra_to_wrt_b.on_segment())
+ {
+ result.assign(Ratio::one(), ra_to_wrt_b);
+ }
+ else if (rb_to_wrt_a.in_segment())
+ {
+ result.assign(rb_to_wrt_a, Ratio::one());
+ }
+
+ return result;
+ }
+
+ static inline return_type disjoint()
+ {
+ return return_type();
+ }
+ static inline return_type error(std::string const&)
+ {
+ return return_type();
+ }
+
+ template <typename Segment>
+ static inline return_type degenerate(Segment const& segment, bool)
+ {
+ return return_type();
+ }
+
+ template <typename Segment, typename Ratio>
+ static inline return_type one_degenerate(Segment const& ,
+ Ratio const& ratio, bool a_degenerate)
+ {
+ return_type result;
+ if (a_degenerate)
+ {
+ // IP lies on ratio w.r.t. segment b
+ result.assign(Ratio::zero(), ratio);
+ }
+ else
+ {
+ result.assign(ratio, Ratio::zero());
+ }
+ return result;
+ }
+
+};
+
+
+}} // namespace policies::relate
+
+}} // namespace boost::geometry
+
+#endif // BOOST_GEOMETRY_GEOMETRY_POLICIES_RELATE_INTERSECTION_RATIOS_HPP