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// Boost.Geometry (aka GGL, Generic Geometry Library)
// Copyright (c) 2020 Barend Gehrels, Amsterdam, the Netherlands.
// Copyright (c) 2023 Adam Wulkiewicz, Lodz, Poland.
// This file was modified by Oracle on 2023.
// Modifications copyright (c) 2023 Oracle and/or its affiliates.
// Contributed and/or modified by Vissarion Fysikopoulos, on behalf of Oracle
// 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_STRATEGIES_CARTESIAN_TURN_IN_RING_WINDING_HPP
#define BOOST_GEOMETRY_STRATEGIES_CARTESIAN_TURN_IN_RING_WINDING_HPP
#include <boost/geometry/arithmetic/infinite_line_functions.hpp>
#include <boost/geometry/core/access.hpp>
#include <boost/geometry/core/config.hpp>
#include <boost/geometry/algorithms/detail/make/make.hpp>
#include <boost/geometry/util/math.hpp>
#include <boost/geometry/strategies/cartesian/side_rounded_input.hpp>
namespace boost { namespace geometry
{
namespace strategy { namespace buffer
{
#ifndef DOXYGEN_NO_DETAIL
enum place_on_ring_type
{
// +----offsetted----> (offsetted is considered as outside)
// | |
// | |
// left right (first point outside, rest inside)
// | |
// | |
// <-----original----+ (original is considered as inside)
place_on_ring_offsetted,
place_on_ring_original,
place_on_ring_to_offsetted,
place_on_ring_from_offsetted,
};
template <typename CalculationType>
class turn_in_ring_winding
{
// Implements the winding rule.
// Basic calculations (on a clockwise ring of 5 segments)
// (as everywhere in BG, -1 = right, 0 = on segment, +1 = left)
// +--------2--------+ // P : For 1/3, nothing happens, it returns
// | | // For 2, side is right (-1), multiplier=2, -2
// | P | // For 4, side is right (-1), multiplier=1, -1
// 1 3 // For 5, side is right (-1), multiplier=1, -1, total -4
// | Q | // Q : For 2: -2, for 4: -2, total -4
// | | // R : For 2: -2, for 5: +2, total 0
// +----5---*----4---+ // S : For 2: -1, 3: nothing, 4: +1, total 0
//
// R S
//
public:
struct counter
{
//! Counter, is increased if point is left of a segment (outside),
//! and decreased if point is right of a segment (inside)
int count{0};
int count_on_offsetted{0};
int count_on_origin{0};
int count_on_edge{0};
CalculationType edge_min_fraction{(std::numeric_limits<CalculationType>::max)()};
#if defined(BOOST_GEOMETRY_USE_RESCALING)
CalculationType inside_min_measure{(std::numeric_limits<CalculationType>::max)()};
#endif
inline bool is_inside() const
{
return count < 0 || count_on_origin > 0;
}
inline bool is_on_boundary() const
{
return count_on_origin == 0
&& (count_on_offsetted > 0
|| (count_on_edge > 0 && edge_min_fraction < 1.0e-3)
#if defined(BOOST_GEOMETRY_USE_RESCALING)
|| (count < 0 && inside_min_measure < 1.0e-5)
#endif
);
}
};
using state_type = counter;
template <typename Point, typename PointOfSegment>
static inline bool is_in_vertical_range(Point const& point,
PointOfSegment const& s1,
PointOfSegment const& s2)
{
CalculationType const py = get<1>(point);
CalculationType const s1y = get<1>(s1);
CalculationType const s2y = get<1>(s2);
return s1y < s2y ? (py >= s1y && py <= s2y) : (py >= s2y && py <= s1y);
}
template <typename Point, typename PointOfSegment>
static inline void apply_on_boundary(Point const& point,
PointOfSegment const& s1,
PointOfSegment const& s2,
place_on_ring_type place_on_ring,
counter& the_state)
{
if (place_on_ring == place_on_ring_offsetted)
{
the_state.count_on_offsetted++;
}
else if (place_on_ring == place_on_ring_to_offsetted
|| place_on_ring == place_on_ring_from_offsetted)
{
the_state.count_on_edge++;
auto const line1 = detail::make::make_perpendicular_line<CalculationType>(s1, s2, s1);
auto const line2 = detail::make::make_perpendicular_line<CalculationType>(s2, s1, s2);
auto const value1 = arithmetic::side_value(line1, point);
auto const value2 = arithmetic::side_value(line2, point);
if (value1 >= 0 && value2 >= 0)
{
auto const length_value = value1 + value2;
if (length_value > 0)
{
// If it is to the utmost point s1 or s2, it is "outside"
auto const fraction = (place_on_ring == place_on_ring_to_offsetted ? value2 : value1) / length_value;
if (fraction < the_state.edge_min_fraction)
{
the_state.edge_min_fraction = fraction;
}
}
}
}
else
{
the_state.count_on_origin++;
}
}
template <typename Point, typename PointOfSegment>
static inline bool apply(Point const& point,
PointOfSegment const& s1,
PointOfSegment const& s2,
place_on_ring_type place_on_ring,
bool is_convex,
counter& the_state)
{
int const side = strategy::side::side_rounded_input<CalculationType>::apply(s1, s2, point);
if (is_convex && side > 0)
{
// If the point is left of this segment of a convex piece, it can never be inside.
// Stop further processing
the_state.count = 1;
return false;
}
CalculationType const px = get<0>(point);
CalculationType const s1x = get<0>(s1);
CalculationType const s2x = get<0>(s2);
bool const in_horizontal_range = s1x < s2x ? (px >= s1x && px <= s2x) : (px >= s2x && px <= s1x);
bool const vertical = s1x == s2x;
if (in_horizontal_range || (vertical && is_in_vertical_range(point, s1, s2)))
{
if (side == 0)
{
apply_on_boundary(point, s1, s2, place_on_ring, the_state);
}
#if defined(BOOST_GEOMETRY_USE_RESCALING)
else if (side == -1)
{
auto const line = detail::make::make_infinite_line<CalculationType>(s1, s2);
auto const value = -arithmetic::side_value(line, point);
if (value > 0 && value < the_state.inside_min_measure) { the_state.inside_min_measure = value; }
}
#endif
}
if (in_horizontal_range)
{
auto const on_boundary = the_state.count_on_offsetted + the_state.count_on_edge + the_state.count_on_origin;
if (on_boundary == 0)
{
// Use only absolute comparisons, because the ring is continuous -
// what was missed is there earlier or later, and turns should
// not be counted twice (which can happen if an epsilon is used).
bool const eq1 = s1x == px;
bool const eq2 = s2x == px;
// Account for 1 or 2 for left side (outside)
// and for -1 or -2 for right side (inside)
int const multiplier = eq1 || eq2 ? 1 : 2;
the_state.count += side * multiplier;
}
}
return true;
}
};
#endif // DOXYGEN_NO_DETAIL
}} // namespace strategy::buffer
}} // namespace boost::geometry
#endif // BOOST_GEOMETRY_STRATEGIES_CARTESIAN_TURN_IN_RING_WINDING_HPP
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