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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_JOIN_ROUND_HPP | |
15 | #define BOOST_GEOMETRY_STRATEGIES_CARTESIAN_BUFFER_JOIN_ROUND_HPP | |
16 | ||
17 | #include <algorithm> | |
18 | ||
19 | #include <boost/geometry/core/cs.hpp> | |
20 | #include <boost/geometry/policies/compare.hpp> | |
21 | #include <boost/geometry/strategies/buffer.hpp> | |
22 | #include <boost/geometry/util/math.hpp> | |
23 | #include <boost/geometry/util/select_most_precise.hpp> | |
24 | ||
25 | #ifdef BOOST_GEOMETRY_DEBUG_BUFFER_WARN | |
26 | #include <iostream> | |
27 | #include <boost/geometry/io/wkt/wkt.hpp> | |
28 | #endif | |
29 | ||
30 | ||
31 | namespace boost { namespace geometry | |
32 | { | |
33 | ||
34 | ||
35 | namespace strategy { namespace buffer | |
36 | { | |
37 | ||
38 | /*! | |
39 | \brief Let the buffer create rounded corners | |
40 | \ingroup strategies | |
41 | \details This strategy can be used as JoinStrategy for the buffer algorithm. | |
42 | It creates a rounded corners around each convex vertex. It can be applied | |
43 | for (multi)linestrings and (multi)polygons. | |
44 | This strategy is only applicable for Cartesian coordinate systems. | |
45 | ||
46 | \qbk{ | |
47 | [heading Example] | |
48 | [buffer_join_round] | |
49 | [heading Output] | |
50 | [$img/strategies/buffer_join_round.png] | |
51 | [heading See also] | |
52 | \* [link geometry.reference.algorithms.buffer.buffer_7_with_strategies buffer (with strategies)] | |
53 | \* [link geometry.reference.strategies.strategy_buffer_join_miter join_miter] | |
54 | } | |
55 | */ | |
56 | class join_round | |
57 | { | |
58 | public : | |
59 | ||
60 | //! \brief Constructs the strategy | |
61 | //! \param points_per_circle points which would be used for a full circle | |
62 | explicit inline join_round(std::size_t points_per_circle = 90) | |
63 | : m_points_per_circle(points_per_circle) | |
64 | {} | |
65 | ||
66 | private : | |
67 | template | |
68 | < | |
69 | typename PromotedType, | |
70 | typename Point, | |
71 | typename DistanceType, | |
72 | typename RangeOut | |
73 | > | |
74 | inline void generate_points(Point const& vertex, | |
75 | Point const& perp1, Point const& perp2, | |
76 | DistanceType const& buffer_distance, | |
77 | RangeOut& range_out) const | |
78 | { | |
79 | PromotedType const dx1 = get<0>(perp1) - get<0>(vertex); | |
80 | PromotedType const dy1 = get<1>(perp1) - get<1>(vertex); | |
81 | PromotedType const dx2 = get<0>(perp2) - get<0>(vertex); | |
82 | PromotedType const dy2 = get<1>(perp2) - get<1>(vertex); | |
83 | ||
84 | PromotedType const two_pi = geometry::math::two_pi<PromotedType>(); | |
85 | ||
86 | PromotedType const angle1 = atan2(dy1, dx1); | |
87 | PromotedType angle2 = atan2(dy2, dx2); | |
88 | while (angle2 > angle1) | |
89 | { | |
90 | angle2 -= two_pi; | |
91 | } | |
92 | PromotedType const angle_diff = angle1 - angle2; | |
93 | ||
94 | // Divide the angle into an integer amount of steps to make it | |
95 | // visually correct also for a low number of points / circle | |
96 | ||
97 | // If a full circle is divided into 3 parts (e.g. angle is 125), | |
98 | // the one point in between must still be generated | |
99 | // The calculation below: | |
100 | // - generates 1 point in between for an angle of 125 based on 3 points | |
101 | // - generates 0 points in between for an angle of 90 based on 4 points | |
102 | ||
103 | std::size_t const n = (std::max)(static_cast<std::size_t>( | |
104 | ceil(m_points_per_circle * angle_diff / two_pi)), std::size_t(1)); | |
105 | ||
106 | PromotedType const diff = angle_diff / static_cast<PromotedType>(n); | |
107 | PromotedType a = angle1 - diff; | |
108 | ||
109 | // Walk to n - 1 to avoid generating the last point | |
110 | for (std::size_t i = 0; i < n - 1; i++, a -= diff) | |
111 | { | |
112 | Point p; | |
113 | set<0>(p, get<0>(vertex) + buffer_distance * cos(a)); | |
114 | set<1>(p, get<1>(vertex) + buffer_distance * sin(a)); | |
115 | range_out.push_back(p); | |
116 | } | |
117 | } | |
118 | ||
119 | public : | |
120 | ||
121 | ||
122 | #ifndef DOXYGEN_SHOULD_SKIP_THIS | |
123 | //! Fills output_range with a rounded shape around a vertex | |
124 | template <typename Point, typename DistanceType, typename RangeOut> | |
125 | inline bool apply(Point const& ip, Point const& vertex, | |
126 | Point const& perp1, Point const& perp2, | |
127 | DistanceType const& buffer_distance, | |
128 | RangeOut& range_out) const | |
129 | { | |
130 | typedef typename coordinate_type<Point>::type coordinate_type; | |
131 | typedef typename boost::range_value<RangeOut>::type output_point_type; | |
132 | ||
133 | typedef typename geometry::select_most_precise | |
134 | < | |
135 | typename geometry::select_most_precise | |
136 | < | |
137 | coordinate_type, | |
138 | typename geometry::coordinate_type<output_point_type>::type | |
139 | >::type, | |
140 | double | |
141 | >::type promoted_type; | |
142 | ||
143 | geometry::equal_to<Point> equals; | |
144 | if (equals(perp1, perp2)) | |
145 | { | |
146 | #ifdef BOOST_GEOMETRY_DEBUG_BUFFER_WARN | |
147 | std::cout << "Corner for equal points " << geometry::wkt(ip) << " " << geometry::wkt(perp1) << std::endl; | |
148 | #endif | |
149 | return false; | |
150 | } | |
151 | ||
152 | // Generate 'vectors' | |
153 | coordinate_type vix = (get<0>(ip) - get<0>(vertex)); | |
154 | coordinate_type viy = (get<1>(ip) - get<1>(vertex)); | |
155 | ||
156 | promoted_type length_i = geometry::math::sqrt(vix * vix + viy * viy); | |
157 | DistanceType const bd = geometry::math::abs(buffer_distance); | |
158 | promoted_type prop = bd / length_i; | |
159 | ||
160 | Point bp; | |
161 | set<0>(bp, get<0>(vertex) + vix * prop); | |
162 | set<1>(bp, get<1>(vertex) + viy * prop); | |
163 | ||
164 | range_out.push_back(perp1); | |
165 | generate_points<promoted_type>(vertex, perp1, perp2, bd, range_out); | |
166 | range_out.push_back(perp2); | |
167 | return true; | |
168 | } | |
169 | ||
170 | template <typename NumericType> | |
171 | static inline NumericType max_distance(NumericType const& distance) | |
172 | { | |
173 | return distance; | |
174 | } | |
175 | ||
176 | #endif // DOXYGEN_SHOULD_SKIP_THIS | |
177 | ||
178 | private : | |
179 | std::size_t m_points_per_circle; | |
180 | }; | |
181 | ||
182 | ||
183 | }} // namespace strategy::buffer | |
184 | ||
185 | }} // namespace boost::geometry | |
186 | ||
187 | #endif // BOOST_GEOMETRY_STRATEGIES_CARTESIAN_BUFFER_JOIN_ROUND_HPP |