Anti-Grain Geometry Tutorial
agg_vcgen_bspline.cpp
1 //----------------------------------------------------------------------------
2 // Anti-Grain Geometry - Version 2.4
3 // Copyright (C) 2002-2005 Maxim Shemanarev (http://www.antigrain.com)
4 //
5 // Permission to copy, use, modify, sell and distribute this software
6 // is granted provided this copyright notice appears in all copies.
7 // This software is provided "as is" without express or implied
8 // warranty, and with no claim as to its suitability for any purpose.
9 //
10 //----------------------------------------------------------------------------
11 // Contact: mcseem@antigrain.com
12 // mcseemagg@yahoo.com
13 // http://www.antigrain.com
14 //----------------------------------------------------------------------------
15 
16 #include "agg_vcgen_bspline.h"
17 
18 namespace agg
19 {
20 
21  //------------------------------------------------------------------------
22  vcgen_bspline::vcgen_bspline() :
23  m_src_vertices(),
24  m_spline_x(),
25  m_spline_y(),
26  m_interpolation_step(1.0/50.0),
27  m_closed(0),
28  m_status(initial),
29  m_src_vertex(0)
30  {
31  }
32 
33 
34  //------------------------------------------------------------------------
35  void vcgen_bspline::remove_all()
36  {
37  m_src_vertices.remove_all();
38  m_closed = 0;
39  m_status = initial;
40  m_src_vertex = 0;
41  }
42 
43 
44  //------------------------------------------------------------------------
45  void vcgen_bspline::add_vertex(double x, double y, unsigned cmd)
46  {
47  m_status = initial;
48  if(is_move_to(cmd))
49  {
50  m_src_vertices.modify_last(point_d(x, y));
51  }
52  else
53  {
54  if(is_vertex(cmd))
55  {
56  m_src_vertices.add(point_d(x, y));
57  }
58  else
59  {
60  m_closed = get_close_flag(cmd);
61  }
62  }
63  }
64 
65 
66  //------------------------------------------------------------------------
67  void vcgen_bspline::rewind(unsigned)
68  {
69  m_cur_abscissa = 0.0;
70  m_max_abscissa = 0.0;
71  m_src_vertex = 0;
72  if(m_status == initial && m_src_vertices.size() > 2)
73  {
74  if(m_closed)
75  {
76  m_spline_x.init(m_src_vertices.size() + 8);
77  m_spline_y.init(m_src_vertices.size() + 8);
78  m_spline_x.add_point(0.0, m_src_vertices.prev(m_src_vertices.size() - 3).x);
79  m_spline_y.add_point(0.0, m_src_vertices.prev(m_src_vertices.size() - 3).y);
80  m_spline_x.add_point(1.0, m_src_vertices[m_src_vertices.size() - 3].x);
81  m_spline_y.add_point(1.0, m_src_vertices[m_src_vertices.size() - 3].y);
82  m_spline_x.add_point(2.0, m_src_vertices[m_src_vertices.size() - 2].x);
83  m_spline_y.add_point(2.0, m_src_vertices[m_src_vertices.size() - 2].y);
84  m_spline_x.add_point(3.0, m_src_vertices[m_src_vertices.size() - 1].x);
85  m_spline_y.add_point(3.0, m_src_vertices[m_src_vertices.size() - 1].y);
86  }
87  else
88  {
89  m_spline_x.init(m_src_vertices.size());
90  m_spline_y.init(m_src_vertices.size());
91  }
92  unsigned i;
93  for(i = 0; i < m_src_vertices.size(); i++)
94  {
95  double x = m_closed ? i + 4 : i;
96  m_spline_x.add_point(x, m_src_vertices[i].x);
97  m_spline_y.add_point(x, m_src_vertices[i].y);
98  }
99  m_cur_abscissa = 0.0;
100  m_max_abscissa = m_src_vertices.size() - 1;
101  if(m_closed)
102  {
103  m_cur_abscissa = 4.0;
104  m_max_abscissa += 5.0;
105  m_spline_x.add_point(m_src_vertices.size() + 4, m_src_vertices[0].x);
106  m_spline_y.add_point(m_src_vertices.size() + 4, m_src_vertices[0].y);
107  m_spline_x.add_point(m_src_vertices.size() + 5, m_src_vertices[1].x);
108  m_spline_y.add_point(m_src_vertices.size() + 5, m_src_vertices[1].y);
109  m_spline_x.add_point(m_src_vertices.size() + 6, m_src_vertices[2].x);
110  m_spline_y.add_point(m_src_vertices.size() + 6, m_src_vertices[2].y);
111  m_spline_x.add_point(m_src_vertices.size() + 7, m_src_vertices.next(2).x);
112  m_spline_y.add_point(m_src_vertices.size() + 7, m_src_vertices.next(2).y);
113  }
114  m_spline_x.prepare();
115  m_spline_y.prepare();
116  }
117  m_status = ready;
118  }
119 
120 
121 
122 
123 
124 
125  //------------------------------------------------------------------------
126  unsigned vcgen_bspline::vertex(double* x, double* y)
127  {
128  unsigned cmd = path_cmd_line_to;
129  while(!is_stop(cmd))
130  {
131  switch(m_status)
132  {
133  case initial:
134  rewind(0);
135 
136  case ready:
137  if(m_src_vertices.size() < 2)
138  {
139  cmd = path_cmd_stop;
140  break;
141  }
142 
143  if(m_src_vertices.size() == 2)
144  {
145  *x = m_src_vertices[m_src_vertex].x;
146  *y = m_src_vertices[m_src_vertex].y;
147  m_src_vertex++;
148  if(m_src_vertex == 1) return path_cmd_move_to;
149  if(m_src_vertex == 2) return path_cmd_line_to;
150  cmd = path_cmd_stop;
151  break;
152  }
153 
154  cmd = path_cmd_move_to;
155  m_status = polygon;
156  m_src_vertex = 0;
157 
158  case polygon:
159  if(m_cur_abscissa >= m_max_abscissa)
160  {
161  if(m_closed)
162  {
163  m_status = end_poly;
164  break;
165  }
166  else
167  {
168  *x = m_src_vertices[m_src_vertices.size() - 1].x;
169  *y = m_src_vertices[m_src_vertices.size() - 1].y;
170  m_status = end_poly;
171  return path_cmd_line_to;
172  }
173  }
174 
175  *x = m_spline_x.get_stateful(m_cur_abscissa);
176  *y = m_spline_y.get_stateful(m_cur_abscissa);
177  m_src_vertex++;
178  m_cur_abscissa += m_interpolation_step;
179  return (m_src_vertex == 1) ? path_cmd_move_to : path_cmd_line_to;
180 
181  case end_poly:
182  m_status = stop;
183  return path_cmd_end_poly | m_closed;
184 
185  case stop:
186  return path_cmd_stop;
187  }
188  }
189  return cmd;
190  }
191 
192 
193 }
194 
agg
Definition: agg_arc.cpp:24