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// Boost.Geometry
// Copyright (c) 2018-2022 Barend Gehrels, Amsterdam, the Netherlands.
// This file was modified by Oracle on 2020-2021.
// Modifications copyright (c) 2020-2021 Oracle and/or its affiliates.
// Contributed and/or modified by Adam Wulkiewicz, 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_GEOGRAPHIC_BUFFER_POINT_CIRCLE_HPP
#define BOOST_GEOMETRY_STRATEGIES_GEOGRAPHIC_BUFFER_POINT_CIRCLE_HPP
#include <cstddef>
#include <boost/range/value_type.hpp>
#include <boost/geometry/core/radian_access.hpp>
#include <boost/geometry/srs/spheroid.hpp>
#include <boost/geometry/strategies/buffer.hpp>
#include <boost/geometry/strategies/geographic/buffer_helper.hpp>
#include <boost/geometry/strategies/geographic/parameters.hpp>
#include <boost/geometry/util/math.hpp>
#include <boost/geometry/util/select_calculation_type.hpp>
namespace boost { namespace geometry
{
namespace strategy { namespace buffer
{
/*!
\brief Create a circular buffer around a point, on the Earth
\ingroup strategies
\details This strategy can be used as PointStrategy for the buffer algorithm.
It creates a circular buffer around a point, on the Earth. It can be applied
for points and multi_points.
\qbk{
[heading Example]
[buffer_geographic_point_circle]
[buffer_geographic_point_circle_output]
[heading See also]
\* [link geometry.reference.algorithms.buffer.buffer_7_with_strategies buffer (with strategies)]
\* [link geometry.reference.strategies.strategy_buffer_point_circle point_circle]
\* [link geometry.reference.strategies.strategy_buffer_point_square point_square]
}
*/
template
<
typename FormulaPolicy = strategy::andoyer,
typename Spheroid = srs::spheroid<double>,
typename CalculationType = void
>
class geographic_point_circle
{
public :
//! \brief Constructs the strategy with a spheroid
//! \param spheroid The spheroid to be used
//! \param count Number of points (minimum 3) for the created circle
explicit inline geographic_point_circle(Spheroid const& spheroid,
std::size_t count = default_points_per_circle)
: m_spheroid(spheroid)
, m_count(get_point_count_for_circle(count))
{}
//! \brief Constructs the strategy
//! \param count Number of points (minimum 3) for the created circle
explicit inline geographic_point_circle(std::size_t count = default_points_per_circle)
: m_count(get_point_count_for_circle(count))
{}
#ifndef DOXYGEN_SHOULD_SKIP_THIS
//! Fills range_out with a circle around point using distance_strategy
template
<
typename Point,
typename DistanceStrategy,
typename RangeOut
>
inline void apply(Point const& point,
DistanceStrategy const& distance_strategy,
RangeOut& range_out) const
{
using calc_t = typename select_calculation_type
<
Point,
typename boost::range_value<RangeOut>::type,
CalculationType
>::type;
using helper = geographic_buffer_helper<FormulaPolicy, calc_t>;
calc_t const lon_rad = get_as_radian<0>(point);
calc_t const lat_rad = get_as_radian<1>(point);
calc_t const buffer_distance = distance_strategy.apply(point,
point, strategy::buffer::buffer_side_left);
calc_t const two_pi = geometry::math::two_pi<calc_t>();
calc_t const pi = geometry::math::pi<calc_t>();
calc_t const diff = two_pi / calc_t(m_count);
calc_t angle = -pi;
for (std::size_t i = 0; i < m_count; i++, angle += diff)
{
// If angle is zero, shift angle a tiny bit to avoid spikes.
calc_t const eps = angle == 0 ? 1.0e-10 : 0.0;
helper::append_point(lon_rad, lat_rad, buffer_distance, angle + eps, m_spheroid, range_out);
}
{
// Close the range
auto const p = range_out.front();
range_out.push_back(p);
}
}
#endif // DOXYGEN_SHOULD_SKIP_THIS
private :
Spheroid m_spheroid;
std::size_t m_count;
};
}} // namespace strategy::buffer
}} // namespace boost::geometry
#endif // BOOST_GEOMETRY_STRATEGIES_GEOGRAPHIC_BUFFER_POINT_CIRCLE_HPP
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