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1 | // Boost.Geometry (aka GGL, Generic Geometry Library) |
2 | // Copyright (c) 2012-2014 Barend Gehrels, Amsterdam, the Netherlands. | |
3 | // Use, modification and distribution is subject to the Boost Software License, | |
4 | // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at | |
5 | // http://www.boost.org/LICENSE_1_0.txt) | |
6 | ||
7 | #ifndef BOOST_GEOMETRY_STRATEGIES_CARTESIAN_BUFFER_SIDE_STRAIGHT_HPP | |
8 | #define BOOST_GEOMETRY_STRATEGIES_CARTESIAN_BUFFER_SIDE_STRAIGHT_HPP | |
9 | ||
10 | #include <cstddef> | |
11 | ||
12 | #include <boost/math/special_functions/fpclassify.hpp> | |
13 | ||
14 | #include <boost/geometry/core/coordinate_type.hpp> | |
15 | #include <boost/geometry/core/access.hpp> | |
16 | #include <boost/geometry/util/math.hpp> | |
17 | #include <boost/geometry/util/select_most_precise.hpp> | |
18 | ||
19 | #include <boost/geometry/strategies/buffer.hpp> | |
20 | #include <boost/geometry/strategies/side.hpp> | |
21 | ||
22 | ||
23 | ||
24 | namespace boost { namespace geometry | |
25 | { | |
26 | ||
27 | namespace strategy { namespace buffer | |
28 | { | |
29 | ||
30 | ||
31 | ||
32 | /*! | |
33 | \brief Let the buffer use straight sides along segments (the default) | |
34 | \ingroup strategies | |
35 | \details This strategy can be used as SideStrategy for the buffer algorithm. | |
36 | It is currently the only provided strategy for this purpose | |
37 | ||
38 | \qbk{ | |
39 | [heading Example] | |
40 | See the examples for other buffer strategies\, for example | |
41 | [link geometry.reference.strategies.strategy_buffer_join_round join_round] | |
42 | [heading See also] | |
43 | \* [link geometry.reference.algorithms.buffer.buffer_7_with_strategies buffer (with strategies)] | |
44 | } | |
45 | */ | |
46 | class side_straight | |
47 | { | |
48 | public : | |
49 | #ifndef DOXYGEN_SHOULD_SKIP_THIS | |
50 | template | |
51 | < | |
52 | typename Point, | |
53 | typename OutputRange, | |
54 | typename DistanceStrategy | |
55 | > | |
56 | static inline result_code apply( | |
57 | Point const& input_p1, Point const& input_p2, | |
58 | buffer_side_selector side, | |
59 | DistanceStrategy const& distance, | |
60 | OutputRange& output_range) | |
61 | { | |
62 | typedef typename coordinate_type<Point>::type coordinate_type; | |
63 | typedef typename geometry::select_most_precise | |
64 | < | |
65 | coordinate_type, | |
66 | double | |
67 | >::type promoted_type; | |
68 | ||
69 | // Generate a block along (left or right of) the segment | |
70 | ||
71 | // Simulate a vector d (dx,dy) | |
72 | coordinate_type const dx = get<0>(input_p2) - get<0>(input_p1); | |
73 | coordinate_type const dy = get<1>(input_p2) - get<1>(input_p1); | |
74 | ||
75 | // For normalization [0,1] (=dot product d.d, sqrt) | |
76 | promoted_type const length = geometry::math::sqrt(dx * dx + dy * dy); | |
77 | ||
78 | if (! boost::math::isfinite(length)) | |
79 | { | |
80 | // In case of coordinates differences of e.g. 1e300, length | |
81 | // will overflow and we should not generate output | |
82 | #ifdef BOOST_GEOMETRY_DEBUG_BUFFER_WARN | |
83 | std::cout << "Error in length calculation for points " | |
84 | << geometry::wkt(input_p1) << " " << geometry::wkt(input_p2) | |
85 | << " length: " << length << std::endl; | |
86 | #endif | |
87 | return result_error_numerical; | |
88 | } | |
89 | ||
90 | if (geometry::math::equals(length, 0)) | |
91 | { | |
92 | // Coordinates are simplified and therefore most often not equal. | |
93 | // But if simplify is skipped, or for lines with two | |
94 | // equal points, length is 0 and we cannot generate output. | |
95 | return result_no_output; | |
96 | } | |
97 | ||
98 | promoted_type const d = distance.apply(input_p1, input_p2, side); | |
99 | ||
100 | // Generate the normalized perpendicular p, to the left (ccw) | |
101 | promoted_type const px = -dy / length; | |
102 | promoted_type const py = dx / length; | |
103 | ||
104 | if (geometry::math::equals(px, 0) | |
105 | && geometry::math::equals(py, 0)) | |
106 | { | |
107 | // This basically should not occur - because of the checks above. | |
108 | // There are no unit tests triggering this condition | |
109 | #ifdef BOOST_GEOMETRY_DEBUG_BUFFER_WARN | |
110 | std::cout << "Error in perpendicular calculation for points " | |
111 | << geometry::wkt(input_p1) << " " << geometry::wkt(input_p2) | |
112 | << " length: " << length | |
113 | << " distance: " << d | |
114 | << std::endl; | |
115 | #endif | |
116 | return result_no_output; | |
117 | } | |
118 | ||
119 | output_range.resize(2); | |
120 | ||
121 | set<0>(output_range.front(), get<0>(input_p1) + px * d); | |
122 | set<1>(output_range.front(), get<1>(input_p1) + py * d); | |
123 | set<0>(output_range.back(), get<0>(input_p2) + px * d); | |
124 | set<1>(output_range.back(), get<1>(input_p2) + py * d); | |
125 | ||
126 | return result_normal; | |
127 | } | |
128 | #endif // DOXYGEN_SHOULD_SKIP_THIS | |
129 | }; | |
130 | ||
131 | ||
132 | }} // namespace strategy::buffer | |
133 | ||
134 | }} // namespace boost::geometry | |
135 | ||
136 | #endif // BOOST_GEOMETRY_STRATEGIES_CARTESIAN_BUFFER_SIDE_STRAIGHT_HPP |