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polygon/poly2tri/common/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 namespace p2t {
42 const double PI_3div4 = 3 * M_PI / 4;
43 const double PI_div2 = 1.57079632679489661923;
44 const double EPSILON = 1e-12;
45 
48 };
49 
61 {
62  double detleft = (pa.x - pc.x) * (pb.y - pc.y);
63  double detright = (pa.y - pc.y) * (pb.x - pc.x);
64  double val = detleft - detright;
65 
66  if( val > -EPSILON && val < EPSILON )
67  {
68  return COLLINEAR;
69  }
70  else if( val > 0 )
71  {
72  return CCW;
73  }
74 
75  return CW;
76 }
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( Point& pa, Point& pb, Point& pc, Point& pd )
114 {
115  double oadb = (pa.x - pb.x) * (pd.y - pb.y) - (pd.x - pb.x) * (pa.y - pb.y);
116 
117  if( oadb >= -EPSILON )
118  {
119  return false;
120  }
121 
122  double oadc = (pa.x - pc.x) * (pd.y - pc.y) - (pd.x - pc.x) * (pa.y - pc.y);
123 
124  if( oadc <= EPSILON )
125  {
126  return false;
127  }
128 
129  return true;
130 }
131 }
132 
133 #endif
bool InScanArea(Point &pa, Point &pb, Point &pc, Point &pd)
const double PI_div2
double y
Definition: shapes.h:46
const double PI_3div4
double x
Definition: shapes.h:46
Orientation Orient2d(Point &pa, Point &pb, Point &pc)
Forumla to calculate signed area Positive if CCW Negative if CW 0 if collinear ...
const double EPSILON
Sweep-line, Constrained Delauney Triangulation (CDT) See: Domiter, V.
Definition: shapes.h:41