1 // Boost.Geometry 2 3 // Copyright (c) 2018-2019 Barend Gehrels, Amsterdam, the Netherlands. 4 5 // Use, modification and distribution is subject to the Boost Software License, 6 // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at 7 // http://www.boost.org/LICENSE_1_0.txt) 8 9 #ifndef BOOST_GEOMETRY_STRATEGIES_GEOGRAPHIC_BUFFER_POINT_CIRCLE_HPP 10 #define BOOST_GEOMETRY_STRATEGIES_GEOGRAPHIC_BUFFER_POINT_CIRCLE_HPP 11 12 #include <cstddef> 13 14 #include <boost/range.hpp> 15 16 #include <boost/geometry/util/math.hpp> 17 18 #include <boost/geometry/strategies/buffer.hpp> 19 20 21 namespace boost { namespace geometry 22 { 23 24 namespace strategy { namespace buffer 25 { 26 27 /*! 28 \brief Create a circular buffer around a point, on the Earth 29 \ingroup strategies 30 \details This strategy can be used as PointStrategy for the buffer algorithm. 31 It creates a circular buffer around a point, on the Earth. It can be applied 32 for points and multi_points. 33 34 \qbk{ 35 [heading Example] 36 [buffer_geographic_point_circle] 37 [buffer_geographic_point_circle_output] 38 [heading See also] 39 \* [link geometry.reference.algorithms.buffer.buffer_7_with_strategies buffer (with strategies)] 40 \* [link geometry.reference.strategies.strategy_buffer_point_circle point_circle] 41 \* [link geometry.reference.strategies.strategy_buffer_point_square point_square] 42 } 43 */ 44 template 45 < 46 typename FormulaPolicy = strategy::andoyer, 47 typename Spheroid = srs::spheroid<double>, 48 typename CalculationType = void 49 > 50 class geographic_point_circle 51 { 52 public : 53 //! \brief Constructs the strategy 54 //! \param count number of points for the created circle (if count 55 //! is smaller than 3, count is internally set to 3) geographic_point_circle(std::size_t count=90)56 explicit geographic_point_circle(std::size_t count = 90) 57 : m_count((count < 3u) ? 3u : count) 58 {} 59 60 #ifndef DOXYGEN_SHOULD_SKIP_THIS 61 //! Fills output_range with a circle around point using distance_strategy 62 template 63 < 64 typename Point, 65 typename OutputRange, 66 typename DistanceStrategy 67 > apply(Point const & point,DistanceStrategy const & distance_strategy,OutputRange & output_range) const68 inline void apply(Point const& point, 69 DistanceStrategy const& distance_strategy, 70 OutputRange& output_range) const 71 { 72 typedef typename boost::range_value<OutputRange>::type output_point_type; 73 74 typedef typename select_most_precise 75 < 76 typename geometry::coordinate_type<Point>::type, 77 typename geometry::coordinate_type<output_point_type>::type, 78 CalculationType 79 //double 80 >::type calculation_type; 81 82 calculation_type const buffer_distance = distance_strategy.apply(point, point, 83 strategy::buffer::buffer_side_left); 84 85 typedef typename FormulaPolicy::template direct 86 < 87 calculation_type, true, false, false, false 88 > direct_t; 89 90 calculation_type const two_pi = geometry::math::two_pi<calculation_type>(); 91 calculation_type const pi = geometry::math::pi<calculation_type>(); 92 93 calculation_type const diff = two_pi / calculation_type(m_count); 94 // TODO: after calculation of some angles is corrected, 95 // we can start at 0.0 96 calculation_type angle = 0.001; 97 98 for (std::size_t i = 0; i < m_count; i++, angle += diff) 99 { 100 if (angle > pi) 101 { 102 angle -= two_pi; 103 } 104 105 typename direct_t::result_type 106 dir_r = direct_t::apply(get_as_radian<0>(point), get_as_radian<1>(point), 107 buffer_distance, angle, 108 m_spheroid); 109 output_point_type p; 110 set_from_radian<0>(p, dir_r.lon2); 111 set_from_radian<1>(p, dir_r.lat2); 112 output_range.push_back(p); 113 } 114 115 { 116 // Close the range 117 const output_point_type p = output_range.front(); 118 output_range.push_back(p); 119 } 120 } 121 #endif // DOXYGEN_SHOULD_SKIP_THIS 122 123 private : 124 std::size_t m_count; 125 Spheroid m_spheroid; 126 }; 127 128 129 }} // namespace strategy::buffer 130 131 }} // namespace boost::geometry 132 133 #endif // BOOST_GEOMETRY_STRATEGIES_GEOGRAPHIC_BUFFER_POINT_CIRCLE_HPP 134