1 // Arc.cpp
2
3 // Copyright 2011, Dan Heeks
4 // This program is released under the BSD license. See the file COPYING for details.
5
6 #include "Arc.h"
7 #include "Curve.h"
8
SetDirWithPoint(const Point & p)9 void CArc::SetDirWithPoint(const Point& p)
10 {
11 double angs = atan2(m_s.y - m_c.y, m_s.x - m_c.x);
12 double ange = atan2(m_e.y - m_c.y, m_e.x - m_c.x);
13 double angp = atan2(p.y - m_c.y, p.x - m_c.x);
14 if(ange < angs)ange += 6.2831853071795864;
15 if(angp < angs - 0.0000000000001)angp += 6.2831853071795864;
16 if(angp > ange + 0.0000000000001)m_dir = false;
17 else m_dir = true;
18 }
19
IncludedAngle() const20 double CArc::IncludedAngle()const
21 {
22 double angs = atan2(m_s.y - m_c.y, m_s.x - m_c.x);
23 double ange = atan2(m_e.y - m_c.y, m_e.x - m_c.x);
24 if(m_dir)
25 {
26 // make sure ange > angs
27 if(ange < angs)ange += 6.2831853071795864;
28 }
29 else
30 {
31 // make sure angs > ange
32 if(angs < ange)angs += 6.2831853071795864;
33 }
34
35 return fabs(ange - angs);
36 }
37
AlmostALine(double accuracy) const38 bool CArc::AlmostALine(double accuracy)const
39 {
40 Point mid_point = MidParam(0.5);
41 if(Line2d(m_s, m_e - m_s).Dist(mid_point) <= accuracy)
42 return true;
43
44 const double max_arc_radius = 1.0 / geoff_geometry::TOLERANCE;
45 double radius = m_c.dist(m_s);
46 if (radius > max_arc_radius)
47 {
48 return true; // We don't want to produce an arc whose radius is too large.
49 }
50
51 return false;
52 }
53
MidParam(double param) const54 Point CArc::MidParam(double param)const {
55 /// returns a point which is 0-1 along arc
56 if(fabs(param) < 0.00000000000001)return m_s;
57 if(fabs(param - 1.0) < 0.00000000000001)return m_e;
58
59 Point p;
60 Point v = m_s - m_c;
61 v.Rotate(param * IncludedAngle());
62 p = v + m_c;
63
64 return p;
65 }
66
67 //segments - number of segments per full revolution!
68 //d_angle - determines the direction and the ammount of the arc to draw
GetSegments(void (* callbackfunc)(const double * p),double pixels_per_mm) const69 void CArc::GetSegments(void(*callbackfunc)(const double *p), double pixels_per_mm)const
70 {
71 if(m_s == m_e)
72 return;
73
74 Point Va = m_s - m_c;
75 Point Vb = m_e - m_c;
76
77 double start_angle = atan2(Va.y, Va.x);
78 double end_angle = atan2(Vb.y, Vb.x);
79
80 if(m_dir)
81 {
82 if(start_angle > end_angle)end_angle += 6.28318530717958;
83 }
84 else
85 {
86 if(start_angle < end_angle)end_angle -= 6.28318530717958;
87 }
88
89 double radius = m_c.dist(m_s);
90 double d_angle = end_angle - start_angle;
91 int segments = (int)(fabs(pixels_per_mm * radius * d_angle / 6.28318530717958 + 1));
92
93 double theta = d_angle / (double)segments;
94 while(theta>1.0){segments*=2;theta = d_angle / (double)segments;}
95 double tangetial_factor = tan(theta);
96 double radial_factor = 1 - cos(theta);
97
98 double x = radius * cos(start_angle);
99 double y = radius * sin(start_angle);
100
101 double pp[3] = {0.0, 0.0, 0.0};
102
103 for(int i = 0; i < segments + 1; i++)
104 {
105 Point p = m_c + Point(x, y);
106 pp[0] = p.x;
107 pp[1] = p.y;
108 (*callbackfunc)(pp);
109
110 double tx = -y;
111 double ty = x;
112
113 x += tx * tangetial_factor;
114 y += ty * tangetial_factor;
115
116 double rx = - x;
117 double ry = - y;
118
119 x += rx * radial_factor;
120 y += ry * radial_factor;
121 }
122 }