Point Cloud Library (PCL) 1.12.0
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line_iterator.h
1/*
2 * Software License Agreement (BSD License)
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4 * Copyright (c) 2010, Willow Garage, Inc.
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35
36#pragma once
37
38#include "organized_index_iterator.h"
39
40namespace pcl {
41/**
42 * \brief Organized Index Iterator for iterating over the "pixels" for a given line
43 * using the Bresenham algorithm. Supports 4 and 8 neighborhood connectivity
44 * \note iterator does not visit the given end-point (on purpose).
45 * \author Suat Gedikli <gedikli@willowgarage.com>
46 * \ingroup geometry
47 */
49public:
50 /** \brief Neighborhood connectivity */
51 enum Neighborhood { Neighbor4 = 4, Neighbor8 = 8 };
52
53public:
54 /**
55 * \brief Constructor
56 * \param x_start column of the start pixel of the line
57 * \param y_start row of the start pixel of the line
58 * \param x_end column of the end pixel of the line
59 * \param y_end row of the end pixel of the line
60 * \param width width of the organized structure e.g. image/cloud/map etc..
61 * \param neighborhood connectivity of the neighborhood
62 */
63 LineIterator(unsigned x_start,
64 unsigned y_start,
65 unsigned x_end,
66 unsigned y_end,
67 unsigned width,
68 const Neighborhood& neighborhood = Neighbor8);
69
70 /** \brief Destructor*/
72
73 void
74 operator++() override;
75 unsigned
76 getRowIndex() const override;
77 unsigned
78 getColumnIndex() const override;
79 bool
80 isValid() const override;
81 void
82 reset() override;
83
84protected:
85 /**
86 * \brief initializes the variables for the Bresenham algorithm
87 * \param[in] neighborhood connectivity to the neighborhood. Either 4 or 8
88 */
89 void
90 init(const Neighborhood& neighborhood);
91
92 /** \brief current column index*/
93 unsigned x_;
94
95 /** \brief current row index*/
96 unsigned y_;
97
98 /** \brief column index of first pixel/point*/
99 unsigned x_start_;
100
101 /** \brief row index of first pixel/point*/
102 unsigned y_start_;
103
104 /** \brief column index of end pixel/point*/
105 unsigned x_end_;
106
107 /** \brief row index of end pixel/point*/
108 unsigned y_end_;
109
110 // calculated values
111 /** \brief current distance to the line*/
113
114 /** \brief error threshold*/
116
117 /** \brief increment of error (distance) value in case of an y-step (if dx > dy)*/
119
120 /** \brief increment of error (distance) value in case of just an x-step (if dx >
121 * dy)*/
123
124 /** \brief increment of column index in case of just an x-step (if dx > dy)*/
126
127 /** \brief increment of row index in case of just an x-step (if dx > dy)*/
129
130 /** \brief increment of column index in case of just an y-step (if dx > dy)*/
132
133 /** \brief increment of row index in case of just an y-step (if dx > dy)*/
135
136 /** \brief increment pixel/point index in case of just an x-step (if dx > dy)*/
138
139 /** \brief increment pixel/point index in case of just an y-step (if dx > dy)*/
141};
142
143////////////////////////////////////////////////////////////////////////////////
144////////////////////////////////////////////////////////////////////////////////
145////////////////////////////////////////////////////////////////////////////////
146
147////////////////////////////////////////////////////////////////////////////////
148inline LineIterator::LineIterator(unsigned x_start,
149 unsigned y_start,
150 unsigned x_end,
151 unsigned y_end,
152 unsigned width,
153 const Neighborhood& neighborhood)
155, x_start_(x_start)
156, y_start_(y_start)
157, x_end_(x_end)
158, y_end_(y_end)
159{
160 init(neighborhood);
161}
162
163////////////////////////////////////////////////////////////////////////////////
165
166////////////////////////////////////////////////////////////////////////////////
167inline void
169{
170 x_ = x_start_;
171 y_ = y_start_;
172 index_ = x_ * width_ + y_;
173 error_ = 0;
174
175 int delta_x = x_end_ - x_start_;
176 int delta_y = y_end_ - y_start_;
177
178 int x_dir = ((delta_x > 0) ? 1 : -1);
179 int y_dir = ((delta_y > 0) ? 1 : -1);
180
181 delta_x *= x_dir;
182 delta_y *= y_dir;
183
184 if (delta_x >= delta_y) {
185 if (neighborhood == Neighbor4) {
186 error_max_ = delta_x - delta_y;
187 x_minus_ = 0;
188 y_minus_ = y_dir;
189 x_plus_ = x_dir;
190 y_plus_ = 0;
191
192 error_minus_ = -(delta_x * 2);
193 error_plus_ = (delta_y * 2);
194 }
195 else {
196 error_max_ = delta_x - (delta_y * 2);
197 x_minus_ = x_dir;
198 y_minus_ = y_dir;
199 x_plus_ = x_dir;
200 y_plus_ = 0;
201
202 error_minus_ = (delta_y - delta_x) * 2;
203 error_plus_ = (delta_y * 2);
204 }
205 }
206 else {
207 if (neighborhood == Neighbor4) {
208 error_max_ = delta_y - delta_x;
209 x_minus_ = x_dir;
210 y_minus_ = 0;
211 x_plus_ = 0;
212 y_plus_ = y_dir;
213
214 error_minus_ = -(delta_y * 2);
215 error_plus_ = (delta_x * 2);
216 }
217 else {
218 error_max_ = delta_y - (delta_x * 2);
219 x_minus_ = x_dir;
220 y_minus_ = y_dir;
221 x_plus_ = 0;
222 y_plus_ = y_dir;
223
224 error_minus_ = (delta_x - delta_y) * 2;
225 error_plus_ = (delta_x * 2);
226 }
227 }
228
231}
232
233////////////////////////////////////////////////////////////////////////////////
234inline void
236{
237 if (error_ >= error_max_) {
238 x_ += x_minus_;
239 y_ += y_minus_;
242 }
243 else {
244 x_ += x_plus_;
245 y_ += y_plus_;
248 }
249}
250
251////////////////////////////////////////////////////////////////////////////////
252inline unsigned
254{
255 return y_;
256}
257
258////////////////////////////////////////////////////////////////////////////////
259inline unsigned
261{
262 return x_;
263}
264
265////////////////////////////////////////////////////////////////////////////////
266inline bool
268{
269 return (x_ != x_end_ || y_ != y_end_);
270}
271
272////////////////////////////////////////////////////////////////////////////////
273inline void
275{
276 x_ = x_start_;
277 y_ = y_start_;
278 error_ = 0;
279 index_ = x_ * width_ + y_;
280}
281
282} // namespace pcl
Organized Index Iterator for iterating over the "pixels" for a given line using the Bresenham algorit...
unsigned x_end_
column index of end pixel/point
void operator++() override
go to next pixel/point in image/cloud
int y_minus_
increment of row index in case of just an y-step (if dx > dy)
unsigned getColumnIndex() const override
returns the col index (x-coordinate) of the current pixel/point
int index_minus_
increment pixel/point index in case of just an y-step (if dx > dy)
unsigned y_
current row index
void reset() override
resets the iterator to the beginning of the line
int x_minus_
increment of column index in case of just an y-step (if dx > dy)
unsigned getRowIndex() const override
returns the row index (y-coordinate) of the current pixel/point
unsigned y_end_
row index of end pixel/point
LineIterator(unsigned x_start, unsigned y_start, unsigned x_end, unsigned y_end, unsigned width, const Neighborhood &neighborhood=Neighbor8)
Constructor.
int error_minus_
increment of error (distance) value in case of an y-step (if dx > dy)
int error_plus_
increment of error (distance) value in case of just an x-step (if dx > dy)
void init(const Neighborhood &neighborhood)
initializes the variables for the Bresenham algorithm
Neighborhood
Neighborhood connectivity
int y_plus_
increment of row index in case of just an x-step (if dx > dy)
int index_plus_
increment pixel/point index in case of just an x-step (if dx > dy)
int x_plus_
increment of column index in case of just an x-step (if dx > dy)
~LineIterator()
Destructor.
unsigned x_
current column index
unsigned y_start_
row index of first pixel/point
int error_max_
error threshold
int error_
current distance to the line
unsigned x_start_
column index of first pixel/point
bool isValid() const override
return whether the current visited pixel/point is valid or not.
base class for iterators on 2-dimensional maps like images/organized clouds etc.
unsigned width_
the width of the image/cloud
unsigned index_
the index of the current pixel/point