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// Boost.Geometry (aka GGL, Generic Geometry Library)
// Copyright (c) 2007-2015 Barend Gehrels, Amsterdam, the Netherlands.
// Copyright (c) 2008-2015 Bruno Lalande, Paris, France.
// Copyright (c) 2009-2015 Mateusz Loskot, London, UK.
// Copyright (c) 2013-2015 Adam Wulkiewicz, Lodz, Poland.
// This file was modified by Oracle on 2015.
// Modifications copyright (c) 2015 Oracle and/or its affiliates.
// Contributed and/or modified by Menelaos Karavelas, 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_ALGORITHMS_DETAIL_POINT_IS_EQUAL_OR_SPIKE_HPP
#define BOOST_GEOMETRY_ALGORITHMS_DETAIL_POINT_IS_EQUAL_OR_SPIKE_HPP
#include <boost/geometry/algorithms/detail/direction_code.hpp>
#include <boost/geometry/algorithms/detail/recalculate.hpp>
#include <boost/geometry/policies/robustness/robust_point_type.hpp>
#include <boost/geometry/strategies/side.hpp>
#include <boost/geometry/util/condition.hpp>
#include <boost/geometry/util/math.hpp>
namespace boost { namespace geometry
{
#ifndef DOXYGEN_NO_DETAIL
namespace detail
{
// Checks if a point ("last_point") causes a spike w.r.t.
// the specified two other points (segment_a, segment_b)
//
// x-------x------x
// a lp b
//
// Above, lp generates a spike w.r.t. segment(a,b)
// So specify last point first, then (a,b)
// The segment's orientation does matter: if lp is to the right of b
// no spike is reported
template <typename Point1, typename Point2, typename Point3>
static inline bool point_is_spike_or_equal(Point1 const& last_point,
Point2 const& segment_a,
Point3 const& segment_b)
{
typedef typename strategy::side::services::default_strategy
<
typename cs_tag<Point1>::type
>::type side_strategy;
int const side = side_strategy::apply(last_point, segment_a, segment_b);
if (side == 0)
{
// Last point is collinear w.r.t previous segment.
// Check if it is equal
int const sgn_x1 = sign_of_difference<0>(last_point, segment_b);
int const sgn_y1 = sign_of_difference<1>(last_point, segment_b);
if (sgn_x1 == 0 && sgn_y1 == 0)
{
return true;
}
// Check if it moves forward
int const sgn_x2 = sign_of_difference<0>(segment_b, segment_a);
int const sgn_y2 = sign_of_difference<1>(segment_b, segment_a);
return sgn_x1 != sgn_x2 || sgn_y1 != sgn_y2;
}
return false;
}
template
<
typename Point1,
typename Point2,
typename Point3,
typename RobustPolicy
>
static inline bool point_is_spike_or_equal(Point1 const& last_point,
Point2 const& segment_a,
Point3 const& segment_b,
RobustPolicy const& robust_policy)
{
if (point_is_spike_or_equal(last_point, segment_a, segment_b))
{
return true;
}
if (BOOST_GEOMETRY_CONDITION(! RobustPolicy::enabled))
{
return false;
}
// Try using specified robust policy
typedef typename geometry::robust_point_type
<
Point1,
RobustPolicy
>::type robust_point_type;
robust_point_type last_point_rob, segment_a_rob, segment_b_rob;
geometry::recalculate(last_point_rob, last_point, robust_policy);
geometry::recalculate(segment_a_rob, segment_a, robust_policy);
geometry::recalculate(segment_b_rob, segment_b, robust_policy);
return point_is_spike_or_equal
(
last_point_rob,
segment_a_rob,
segment_b_rob
);
}
} // namespace detail
#endif
}} // namespace boost::geometry
#endif // BOOST_GEOMETRY_ALGORITHMS_DETAIL_POINT_IS_EQUAL_OR_SPIKE_HPP
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