Horizon
utils.h
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31 
32 #ifndef UTILS_H
33 #define UTILS_H
34 
35 // Otherwise #defines like M_PI are undeclared under Visual Studio
36 #define _USE_MATH_DEFINES
37 
38 #include <exception>
39 #include <math.h>
40 
41 // C99 removes M_PI from math.h
42 #ifndef M_PI
43 #define M_PI 3.14159265358979323846264338327
44 #endif
45 
46 namespace p2t {
47 
48 const double PI_3div4 = 3 * M_PI / 4;
49 const double PI_div2 = 1.57079632679489661923;
50 const double EPSILON = 1e-12;
51 
52 enum Orientation { CW, CCW, COLLINEAR };
53 
64 Orientation Orient2d(const Point& pa, const Point& pb, const Point& pc)
65 {
66  double detleft = (pa.x - pc.x) * (pb.y - pc.y);
67  double detright = (pa.y - pc.y) * (pb.x - pc.x);
68  double val = detleft - detright;
69  if (val > -EPSILON && val < EPSILON) {
70  return COLLINEAR;
71  } else if (val > 0) {
72  return CCW;
73  }
74  return CW;
75 }
76 
77 /*
78 bool InScanArea(Point& pa, Point& pb, Point& pc, Point& pd)
79 {
80  double pdx = pd.x;
81  double pdy = pd.y;
82  double adx = pa.x - pdx;
83  double ady = pa.y - pdy;
84  double bdx = pb.x - pdx;
85  double bdy = pb.y - pdy;
86 
87  double adxbdy = adx * bdy;
88  double bdxady = bdx * ady;
89  double oabd = adxbdy - bdxady;
90 
91  if (oabd <= EPSILON) {
92  return false;
93  }
94 
95  double cdx = pc.x - pdx;
96  double cdy = pc.y - pdy;
97 
98  double cdxady = cdx * ady;
99  double adxcdy = adx * cdy;
100  double ocad = cdxady - adxcdy;
101 
102  if (ocad <= EPSILON) {
103  return false;
104  }
105 
106  return true;
107 }
108 
109 */
110 
111 bool InScanArea(const Point& pa, const Point& pb, const Point& pc, const Point& pd)
112 {
113  double oadb = (pa.x - pb.x)*(pd.y - pb.y) - (pd.x - pb.x)*(pa.y - pb.y);
114  if (oadb >= -EPSILON) {
115  return false;
116  }
117 
118  double oadc = (pa.x - pc.x)*(pd.y - pc.y) - (pd.x - pc.x)*(pa.y - pc.y);
119  if (oadc <= EPSILON) {
120  return false;
121  }
122  return true;
123 }
124 
125 }
126 
127 #endif
p2t::Orient2d
Orientation Orient2d(const Point &pa, const Point &pb, const Point &pc)
Forumla to calculate signed area Positive if CCW Negative if CW 0 if collinear
Definition: utils.h:64
p2t
Sweep-line, Constrained Delauney Triangulation (CDT) See: Domiter, V.
Definition: shapes.cpp:34
p2t::Point
Definition: shapes.h:45