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