/src/MapServer/src/renderers/agg/src/agg_arc.cpp
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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 | | // Arc vertex generator |
17 | | // |
18 | | //---------------------------------------------------------------------------- |
19 | | |
20 | | #include <math.h> |
21 | | #include "../include/agg_arc.h" |
22 | | |
23 | | |
24 | | namespace mapserver |
25 | | { |
26 | | //------------------------------------------------------------------------ |
27 | | arc::arc(double x, double y, |
28 | | double rx, double ry, |
29 | | double a1, double a2, |
30 | | bool ccw) : |
31 | 0 | m_x(x), m_y(y), m_rx(rx), m_ry(ry), m_scale(1.0) |
32 | 0 | { |
33 | 0 | normalize(a1, a2, ccw); |
34 | 0 | } |
35 | | |
36 | | //------------------------------------------------------------------------ |
37 | | void arc::init(double x, double y, |
38 | | double rx, double ry, |
39 | | double a1, double a2, |
40 | | bool ccw) |
41 | 0 | { |
42 | 0 | m_x = x; m_y = y; |
43 | 0 | m_rx = rx; m_ry = ry; |
44 | 0 | normalize(a1, a2, ccw); |
45 | 0 | } |
46 | | |
47 | | //------------------------------------------------------------------------ |
48 | | void arc::approximation_scale(double s) |
49 | 0 | { |
50 | 0 | m_scale = s; |
51 | 0 | if(m_initialized) |
52 | 0 | { |
53 | 0 | normalize(m_start, m_end, m_ccw); |
54 | 0 | } |
55 | 0 | } |
56 | | |
57 | | //------------------------------------------------------------------------ |
58 | | void arc::rewind(unsigned) |
59 | 0 | { |
60 | 0 | m_path_cmd = path_cmd_move_to; |
61 | 0 | m_angle = m_start; |
62 | 0 | } |
63 | | |
64 | | //------------------------------------------------------------------------ |
65 | | unsigned arc::vertex(double* x, double* y) |
66 | 0 | { |
67 | 0 | if(is_stop(m_path_cmd)) return path_cmd_stop; |
68 | 0 | if((m_angle < m_end - m_da/4) != m_ccw) |
69 | 0 | { |
70 | 0 | *x = m_x + cos(m_end) * m_rx; |
71 | 0 | *y = m_y + sin(m_end) * m_ry; |
72 | 0 | m_path_cmd = path_cmd_stop; |
73 | 0 | return path_cmd_line_to; |
74 | 0 | } |
75 | | |
76 | 0 | *x = m_x + cos(m_angle) * m_rx; |
77 | 0 | *y = m_y + sin(m_angle) * m_ry; |
78 | |
|
79 | 0 | m_angle += m_da; |
80 | |
|
81 | 0 | unsigned pf = m_path_cmd; |
82 | 0 | m_path_cmd = path_cmd_line_to; |
83 | 0 | return pf; |
84 | 0 | } |
85 | | |
86 | | //------------------------------------------------------------------------ |
87 | | void arc::normalize(double a1, double a2, bool ccw) |
88 | 0 | { |
89 | 0 | double ra = (fabs(m_rx) + fabs(m_ry)) / 2; |
90 | 0 | m_da = acos(ra / (ra + 0.125 / m_scale)) * 2; |
91 | 0 | if(ccw) |
92 | 0 | { |
93 | 0 | while(a2 < a1) a2 += pi * 2.0; |
94 | 0 | } |
95 | 0 | else |
96 | 0 | { |
97 | 0 | while(a1 < a2) a1 += pi * 2.0; |
98 | 0 | m_da = -m_da; |
99 | 0 | } |
100 | 0 | m_ccw = ccw; |
101 | 0 | m_start = a1; |
102 | 0 | m_end = a2; |
103 | 0 | m_initialized = true; |
104 | 0 | } |
105 | | |
106 | | } |