// Boost.Geometry (aka GGL, Generic Geometry Library)
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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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// Copyright (c) 2009-2012 Mateusz Loskot, London, UK.
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// This file was modified by Oracle on 2018, 2019.
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// Modifications copyright (c) 2018, 2019, Oracle and/or its affiliates.
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// Contributed and/or modified by Adam Wulkiewicz, on behalf of Oracle
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// Parts of Boost.Geometry are redesigned from Geodan's Geographic Library
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// (geolib/GGL), copyright (c) 1995-2010 Geodan, 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_STRATEGIES_CARTESIAN_POINT_IN_POLY_CROSSINGS_MULTIPLY_HPP
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#define BOOST_GEOMETRY_STRATEGIES_CARTESIAN_POINT_IN_POLY_CROSSINGS_MULTIPLY_HPP
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#include <boost/geometry/core/access.hpp>
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#include <boost/geometry/core/coordinate_type.hpp>
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#include <boost/geometry/util/select_calculation_type.hpp>
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namespace boost { namespace geometry
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{
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namespace strategy { namespace within
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{
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/*!
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\brief Within detection using cross counting,
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\ingroup strategies
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\tparam Point \tparam_point
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\tparam PointOfSegment \tparam_segment_point
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\tparam CalculationType \tparam_calculation
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\see http://tog.acm.org/resources/GraphicsGems/gemsiv/ptpoly_haines/ptinpoly.c
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\note Does NOT work correctly for point ON border
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\qbk{
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[heading See also]
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[link geometry.reference.algorithms.within.within_3_with_strategy within (with strategy)]
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}
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*/
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template
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<
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typename Point_, // for backward compatibility
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typename PointOfSegment_ = Point_, // for backward compatibility
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typename CalculationType = void
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>
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class crossings_multiply
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{
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template <typename Point, typename PointOfSegment>
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struct calculation_type
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: select_calculation_type
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<
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Point,
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PointOfSegment,
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CalculationType
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>
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{};
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class flags
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{
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bool inside_flag;
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bool first;
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bool yflag0;
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public :
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friend class crossings_multiply;
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inline flags()
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: inside_flag(false)
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, first(true)
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, yflag0(false)
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{}
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};
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public :
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typedef flags state_type;
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template <typename Point, typename PointOfSegment>
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static inline bool apply(Point const& point,
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PointOfSegment const& seg1, PointOfSegment const& seg2,
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flags& state)
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{
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typedef typename calculation_type<Point, PointOfSegment>::type calc_t;
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calc_t const tx = get<0>(point);
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calc_t const ty = get<1>(point);
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calc_t const x0 = get<0>(seg1);
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calc_t const y0 = get<1>(seg1);
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calc_t const x1 = get<0>(seg2);
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calc_t const y1 = get<1>(seg2);
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if (state.first)
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{
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state.first = false;
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state.yflag0 = y0 >= ty;
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}
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bool yflag1 = y1 >= ty;
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if (state.yflag0 != yflag1)
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{
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if ( ((y1-ty) * (x0-x1) >= (x1-tx) * (y0-y1)) == yflag1 )
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{
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state.inside_flag = ! state.inside_flag;
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}
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}
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state.yflag0 = yflag1;
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return true;
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}
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static inline int result(flags const& state)
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{
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return state.inside_flag ? 1 : -1;
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}
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};
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}} // namespace strategy::within
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}} // namespace boost::geometry
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#endif // BOOST_GEOMETRY_STRATEGIES_CARTESIAN_POINT_IN_POLY_CROSSINGS_MULTIPLY_HPP
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