1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
|
// Boost.Geometry (aka GGL, Generic Geometry Library)
// Copyright (c) 2012-2015 Barend Gehrels, Amsterdam, the Netherlands.
// This file was modified by Oracle on 2015.
// Modifications copyright (c) 2015, Oracle and/or its affiliates.
// Contributed and/or modified by Menelaos Karavelas, on behalf of Oracle
// Use, modification and distribution is subject to the Boost Software License,
// Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
#ifndef BOOST_GEOMETRY_STRATEGIES_CARTESIAN_BUFFER_END_ROUND_HPP
#define BOOST_GEOMETRY_STRATEGIES_CARTESIAN_BUFFER_END_ROUND_HPP
#include <boost/core/ignore_unused.hpp>
#include <boost/geometry/core/cs.hpp>
#include <boost/geometry/strategies/tags.hpp>
#include <boost/geometry/util/math.hpp>
#include <boost/geometry/util/select_most_precise.hpp>
#include <boost/geometry/strategies/buffer.hpp>
#include <boost/geometry/io/wkt/wkt.hpp>
namespace boost { namespace geometry
{
namespace strategy { namespace buffer
{
/*!
\brief Let the buffer create rounded ends
\ingroup strategies
\details This strategy can be used as EndStrategy for the buffer algorithm.
It creates a rounded end for each linestring-end. It can be applied
for (multi)linestrings. Also it is applicable for spikes in (multi)polygons.
This strategy is only applicable for Cartesian coordinate systems.
\qbk{
[heading Example]
[buffer_end_round]
[heading Output]
[$img/strategies/buffer_end_round.png]
[heading See also]
\* [link geometry.reference.algorithms.buffer.buffer_7_with_strategies buffer (with strategies)]
\* [link geometry.reference.strategies.strategy_buffer_end_flat end_flat]
}
*/
class end_round
{
private :
std::size_t m_points_per_circle;
template
<
typename Point,
typename PromotedType,
typename DistanceType,
typename RangeOut
>
inline void generate_points(Point const& point,
PromotedType alpha, // by value
DistanceType const& buffer_distance,
RangeOut& range_out) const
{
PromotedType const two_pi = geometry::math::two_pi<PromotedType>();
std::size_t point_buffer_count = m_points_per_circle;
PromotedType const diff = two_pi / PromotedType(point_buffer_count);
// For half circle:
point_buffer_count /= 2;
point_buffer_count++;
for (std::size_t i = 0; i < point_buffer_count; i++, alpha -= diff)
{
typename boost::range_value<RangeOut>::type p;
set<0>(p, get<0>(point) + buffer_distance * cos(alpha));
set<1>(p, get<1>(point) + buffer_distance * sin(alpha));
range_out.push_back(p);
}
}
template <typename T, typename P1, typename P2>
static inline T calculate_angle(P1 const& from_point, P2 const& to_point)
{
typedef P1 vector_type;
vector_type v = from_point;
geometry::subtract_point(v, to_point);
return atan2(geometry::get<1>(v), geometry::get<0>(v));
}
public :
//! \brief Constructs the strategy
//! \param points_per_circle points which would be used for a full circle
//! (if points_per_circle is smaller than 4, it is internally set to 4)
explicit inline end_round(std::size_t points_per_circle = 90)
: m_points_per_circle((points_per_circle < 4u) ? 4u : points_per_circle)
{}
#ifndef DOXYGEN_SHOULD_SKIP_THIS
//! Fills output_range with a flat end
template <typename Point, typename RangeOut, typename DistanceStrategy>
inline void apply(Point const& penultimate_point,
Point const& perp_left_point,
Point const& ultimate_point,
Point const& perp_right_point,
buffer_side_selector side,
DistanceStrategy const& distance,
RangeOut& range_out) const
{
boost::ignore_unused(perp_left_point);
typedef typename coordinate_type<Point>::type coordinate_type;
typedef typename geometry::select_most_precise
<
coordinate_type,
double
>::type promoted_type;
promoted_type const dist_left = distance.apply(penultimate_point, ultimate_point, buffer_side_left);
promoted_type const dist_right = distance.apply(penultimate_point, ultimate_point, buffer_side_right);
promoted_type const alpha
= calculate_angle<promoted_type>(penultimate_point, ultimate_point)
- geometry::math::half_pi<promoted_type>();
if (geometry::math::equals(dist_left, dist_right))
{
generate_points(ultimate_point, alpha, dist_left, range_out);
}
else
{
static promoted_type const two = 2.0;
promoted_type const dist_average = (dist_left + dist_right) / two;
promoted_type const dist_half
= (side == buffer_side_right
? (dist_right - dist_left)
: (dist_left - dist_right)) / two;
Point shifted_point;
set<0>(shifted_point, get<0>(ultimate_point) + dist_half * cos(alpha));
set<1>(shifted_point, get<1>(ultimate_point) + dist_half * sin(alpha));
generate_points(shifted_point, alpha, dist_average, range_out);
}
if (m_points_per_circle % 2 == 1)
{
// For a half circle, if the number of points is not even,
// we should insert the end point too, to generate a full cap
range_out.push_back(perp_right_point);
}
}
template <typename NumericType>
static inline NumericType max_distance(NumericType const& distance)
{
return distance;
}
//! Returns the piece_type (flat end)
static inline piece_type get_piece_type()
{
return buffered_round_end;
}
#endif // DOXYGEN_SHOULD_SKIP_THIS
};
}} // namespace strategy::buffer
}} // namespace boost::geometry
#endif // BOOST_GEOMETRY_STRATEGIES_CARTESIAN_BUFFER_END_ROUND_HPP
|
