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1 | // Boost.Geometry (aka GGL, Generic Geometry Library) | |
2 | ||
3 | // Copyright (c) 2012-2014 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_CARTESIAN_BUFFER_END_FLAT_HPP | |
10 | #define BOOST_GEOMETRY_STRATEGIES_CARTESIAN_BUFFER_END_FLAT_HPP | |
11 | ||
12 | #include <boost/geometry/core/cs.hpp> | |
13 | #include <boost/geometry/strategies/tags.hpp> | |
14 | #include <boost/geometry/strategies/side.hpp> | |
15 | #include <boost/geometry/util/math.hpp> | |
16 | #include <boost/geometry/util/select_most_precise.hpp> | |
17 | ||
18 | #include <boost/geometry/strategies/buffer.hpp> | |
19 | ||
20 | ||
21 | ||
22 | namespace boost { namespace geometry | |
23 | { | |
24 | ||
25 | ||
26 | namespace strategy { namespace buffer | |
27 | { | |
28 | ||
29 | ||
30 | /*! | |
31 | \brief Let the buffer create flat ends | |
32 | \ingroup strategies | |
33 | \details This strategy can be used as EndStrategy for the buffer algorithm. | |
34 | It creates a flat end for each linestring-end. It can be applied | |
35 | for (multi)linestrings. Also it is applicable for spikes in (multi)polygons. | |
36 | This strategy is only applicable for Cartesian coordinate systems. | |
37 | ||
38 | \qbk{ | |
39 | [heading Example] | |
40 | [buffer_end_flat] | |
41 | [heading Output] | |
42 | [$img/strategies/buffer_end_flat.png] | |
43 | [heading See also] | |
44 | \* [link geometry.reference.algorithms.buffer.buffer_7_with_strategies buffer (with strategies)] | |
45 | \* [link geometry.reference.strategies.strategy_buffer_end_round end_round] | |
46 | } | |
47 | */ | |
48 | class end_flat | |
49 | { | |
50 | ||
51 | public : | |
52 | ||
53 | #ifndef DOXYGEN_SHOULD_SKIP_THIS | |
54 | //! Fills output_range with a flat end | |
55 | template <typename Point, typename RangeOut, typename DistanceStrategy> | |
56 | inline void apply(Point const& penultimate_point, | |
57 | Point const& perp_left_point, | |
58 | Point const& ultimate_point, | |
59 | Point const& perp_right_point, | |
60 | buffer_side_selector side, | |
61 | DistanceStrategy const& distance, | |
62 | RangeOut& range_out) const | |
63 | { | |
64 | typedef typename coordinate_type<Point>::type coordinate_type; | |
65 | ||
66 | typedef typename geometry::select_most_precise | |
67 | < | |
68 | coordinate_type, | |
69 | double | |
70 | >::type promoted_type; | |
71 | ||
72 | promoted_type const dist_left = distance.apply(penultimate_point, ultimate_point, buffer_side_left); | |
73 | promoted_type const dist_right = distance.apply(penultimate_point, ultimate_point, buffer_side_right); | |
74 | ||
75 | bool reversed = (side == buffer_side_left && dist_right < 0 && -dist_right > dist_left) | |
76 | || (side == buffer_side_right && dist_left < 0 && -dist_left > dist_right) | |
77 | ; | |
78 | if (reversed) | |
79 | { | |
80 | range_out.push_back(perp_right_point); | |
81 | range_out.push_back(perp_left_point); | |
82 | } | |
83 | else | |
84 | { | |
85 | range_out.push_back(perp_left_point); | |
86 | range_out.push_back(perp_right_point); | |
87 | } | |
88 | // Don't add the ultimate_point (endpoint of the linestring). | |
89 | // The buffer might be generated completely at one side. | |
90 | // In other cases it does no harm but is further useless | |
91 | } | |
92 | ||
93 | template <typename NumericType> | |
94 | static inline NumericType max_distance(NumericType const& distance) | |
95 | { | |
96 | return distance; | |
97 | } | |
98 | ||
99 | //! Returns the piece_type (flat end) | |
100 | static inline piece_type get_piece_type() | |
101 | { | |
102 | return buffered_flat_end; | |
103 | } | |
104 | #endif // DOXYGEN_SHOULD_SKIP_THIS | |
105 | }; | |
106 | ||
107 | ||
108 | }} // namespace strategy::buffer | |
109 | ||
110 | }} // namespace boost::geometry | |
111 | ||
112 | #endif // BOOST_GEOMETRY_STRATEGIES_CARTESIAN_BUFFER_END_FLAT_HPP |