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 "shapes.h"
39 
40 #include <cmath>
41 #include <exception>
42 
43 // C99 removes M_PI from math.h
44 #ifndef M_PI
45 #define M_PI 3.14159265358979323846264338327
46 #endif
47 
48 namespace p2t {
49 
50 const double PI_3div4 = 3 * M_PI / 4;
51 const double PI_div2 = 1.57079632679489661923;
52 const double EPSILON = 1e-12;
53 
54 enum Orientation { CW, CCW, COLLINEAR };
55 
66 Orientation Orient2d(const Point& pa, const Point& pb, const Point& pc)
67 {
68  double detleft = (pa.x - pc.x) * (pb.y - pc.y);
69  double detright = (pa.y - pc.y) * (pb.x - pc.x);
70  double val = detleft - detright;
71  if (val > -EPSILON && val < EPSILON) {
72  return COLLINEAR;
73  } else if (val > 0) {
74  return CCW;
75  }
76  return CW;
77 }
78 
79 /*
80 bool InScanArea(Point& pa, Point& pb, Point& pc, Point& pd)
81 {
82  double pdx = pd.x;
83  double pdy = pd.y;
84  double adx = pa.x - pdx;
85  double ady = pa.y - pdy;
86  double bdx = pb.x - pdx;
87  double bdy = pb.y - pdy;
88 
89  double adxbdy = adx * bdy;
90  double bdxady = bdx * ady;
91  double oabd = adxbdy - bdxady;
92 
93  if (oabd <= EPSILON) {
94  return false;
95  }
96 
97  double cdx = pc.x - pdx;
98  double cdy = pc.y - pdy;
99 
100  double cdxady = cdx * ady;
101  double adxcdy = adx * cdy;
102  double ocad = cdxady - adxcdy;
103 
104  if (ocad <= EPSILON) {
105  return false;
106  }
107 
108  return true;
109 }
110 
111 */
112 
113 bool InScanArea(const Point& pa, const Point& pb, const Point& pc, const Point& pd)
114 {
115  double oadb = (pa.x - pb.x)*(pd.y - pb.y) - (pd.x - pb.x)*(pa.y - pb.y);
116  if (oadb >= -EPSILON) {
117  return false;
118  }
119 
120  double oadc = (pa.x - pc.x)*(pd.y - pc.y) - (pd.x - pc.x)*(pa.y - pc.y);
121  if (oadc <= EPSILON) {
122  return false;
123  }
124  return true;
125 }
126 
127 }
128 
129 #endif
Sweep-line, Constrained Delauney Triangulation (CDT) See: Domiter, V.
Definition: shapes.cpp:36
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:66
Definition: shapes.h:45