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1 | // Boost.Geometry (aka GGL, Generic Geometry Library) |
2 | ||
3 | // Copyright (c) 2012-2015 Barend Gehrels, Amsterdam, the Netherlands. | |
4 | ||
5 | // This file was modified by Oracle on 2015. | |
6 | // Modifications copyright (c) 2015, Oracle and/or its affiliates. | |
7 | ||
8 | // Contributed and/or modified by Menelaos Karavelas, on behalf of Oracle | |
9 | ||
10 | // Use, modification and distribution is subject to the Boost Software License, | |
11 | // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at | |
12 | // http://www.boost.org/LICENSE_1_0.txt) | |
13 | ||
14 | #ifndef BOOST_GEOMETRY_STRATEGIES_CARTESIAN_BUFFER_END_ROUND_HPP | |
15 | #define BOOST_GEOMETRY_STRATEGIES_CARTESIAN_BUFFER_END_ROUND_HPP | |
16 | ||
17 | #include <boost/geometry/core/cs.hpp> | |
18 | #include <boost/geometry/strategies/tags.hpp> | |
19 | #include <boost/geometry/util/math.hpp> | |
20 | #include <boost/geometry/util/select_most_precise.hpp> | |
21 | ||
22 | #include <boost/geometry/strategies/buffer.hpp> | |
23 | ||
24 | ||
25 | #include <boost/geometry/io/wkt/wkt.hpp> | |
26 | ||
27 | namespace boost { namespace geometry | |
28 | { | |
29 | ||
30 | ||
31 | namespace strategy { namespace buffer | |
32 | { | |
33 | ||
34 | ||
35 | /*! | |
36 | \brief Let the buffer create rounded ends | |
37 | \ingroup strategies | |
38 | \details This strategy can be used as EndStrategy for the buffer algorithm. | |
39 | It creates a rounded end for each linestring-end. It can be applied | |
40 | for (multi)linestrings. Also it is applicable for spikes in (multi)polygons. | |
41 | This strategy is only applicable for Cartesian coordinate systems. | |
42 | ||
43 | \qbk{ | |
44 | [heading Example] | |
45 | [buffer_end_round] | |
46 | [heading Output] | |
47 | [$img/strategies/buffer_end_round.png] | |
48 | [heading See also] | |
49 | \* [link geometry.reference.algorithms.buffer.buffer_7_with_strategies buffer (with strategies)] | |
50 | \* [link geometry.reference.strategies.strategy_buffer_end_flat end_flat] | |
51 | } | |
52 | */ | |
53 | class end_round | |
54 | { | |
55 | private : | |
56 | std::size_t m_points_per_circle; | |
57 | ||
58 | template | |
59 | < | |
60 | typename Point, | |
61 | typename PromotedType, | |
62 | typename DistanceType, | |
63 | typename RangeOut | |
64 | > | |
65 | inline void generate_points(Point const& point, | |
66 | PromotedType alpha, // by value | |
67 | DistanceType const& buffer_distance, | |
68 | RangeOut& range_out) const | |
69 | { | |
70 | PromotedType const two_pi = geometry::math::two_pi<PromotedType>(); | |
71 | ||
72 | std::size_t point_buffer_count = m_points_per_circle; | |
73 | ||
74 | PromotedType const diff = two_pi / PromotedType(point_buffer_count); | |
75 | ||
76 | // For half circle: | |
77 | point_buffer_count /= 2; | |
78 | point_buffer_count++; | |
79 | ||
80 | for (std::size_t i = 0; i < point_buffer_count; i++, alpha -= diff) | |
81 | { | |
82 | typename boost::range_value<RangeOut>::type p; | |
83 | set<0>(p, get<0>(point) + buffer_distance * cos(alpha)); | |
84 | set<1>(p, get<1>(point) + buffer_distance * sin(alpha)); | |
85 | range_out.push_back(p); | |
86 | } | |
87 | } | |
88 | ||
89 | template <typename T, typename P1, typename P2> | |
90 | static inline T calculate_angle(P1 const& from_point, P2 const& to_point) | |
91 | { | |
92 | typedef P1 vector_type; | |
93 | vector_type v = from_point; | |
94 | geometry::subtract_point(v, to_point); | |
95 | return atan2(geometry::get<1>(v), geometry::get<0>(v)); | |
96 | } | |
97 | ||
98 | public : | |
99 | ||
100 | //! \brief Constructs the strategy | |
101 | //! \param points_per_circle points which would be used for a full circle | |
102 | //! (if points_per_circle is smaller than 4, it is internally set to 4) | |
103 | explicit inline end_round(std::size_t points_per_circle = 90) | |
104 | : m_points_per_circle((points_per_circle < 4u) ? 4u : points_per_circle) | |
105 | {} | |
106 | ||
107 | #ifndef DOXYGEN_SHOULD_SKIP_THIS | |
108 | ||
109 | //! Fills output_range with a flat end | |
110 | template <typename Point, typename RangeOut, typename DistanceStrategy> | |
111 | inline void apply(Point const& penultimate_point, | |
112 | Point const& perp_left_point, | |
113 | Point const& ultimate_point, | |
114 | Point const& perp_right_point, | |
115 | buffer_side_selector side, | |
116 | DistanceStrategy const& distance, | |
117 | RangeOut& range_out) const | |
118 | { | |
119 | typedef typename coordinate_type<Point>::type coordinate_type; | |
120 | ||
121 | typedef typename geometry::select_most_precise | |
122 | < | |
123 | coordinate_type, | |
124 | double | |
125 | >::type promoted_type; | |
126 | ||
127 | promoted_type const alpha = calculate_angle<promoted_type>(perp_left_point, ultimate_point); | |
128 | ||
129 | promoted_type const dist_left = distance.apply(penultimate_point, ultimate_point, buffer_side_left); | |
130 | promoted_type const dist_right = distance.apply(penultimate_point, ultimate_point, buffer_side_right); | |
131 | if (geometry::math::equals(dist_left, dist_right)) | |
132 | { | |
133 | generate_points(ultimate_point, alpha, dist_left, range_out); | |
134 | } | |
135 | else | |
136 | { | |
137 | promoted_type const two = 2.0; | |
138 | promoted_type dist_half_diff = (dist_left - dist_right) / two; | |
139 | ||
140 | if (side == buffer_side_right) | |
141 | { | |
142 | dist_half_diff = -dist_half_diff; | |
143 | } | |
144 | ||
145 | Point shifted_point; | |
146 | set<0>(shifted_point, get<0>(ultimate_point) + dist_half_diff * cos(alpha)); | |
147 | set<1>(shifted_point, get<1>(ultimate_point) + dist_half_diff * sin(alpha)); | |
148 | generate_points(shifted_point, alpha, (dist_left + dist_right) / two, range_out); | |
149 | } | |
150 | ||
151 | if (m_points_per_circle % 2 == 1) | |
152 | { | |
153 | // For a half circle, if the number of points is not even, | |
154 | // we should insert the end point too, to generate a full cap | |
155 | range_out.push_back(perp_right_point); | |
156 | } | |
157 | } | |
158 | ||
159 | template <typename NumericType> | |
160 | static inline NumericType max_distance(NumericType const& distance) | |
161 | { | |
162 | return distance; | |
163 | } | |
164 | ||
165 | //! Returns the piece_type (flat end) | |
166 | static inline piece_type get_piece_type() | |
167 | { | |
168 | return buffered_round_end; | |
169 | } | |
170 | #endif // DOXYGEN_SHOULD_SKIP_THIS | |
171 | }; | |
172 | ||
173 | ||
174 | }} // namespace strategy::buffer | |
175 | ||
176 | }} // namespace boost::geometry | |
177 | ||
178 | #endif // BOOST_GEOMETRY_STRATEGIES_CARTESIAN_BUFFER_END_ROUND_HPP |