1 /*
2 * Poly2Tri Copyright (c) 2009-2018, Poly2Tri Contributors
3 * https://github.com/jhasse/poly2tri
4 *
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without modification,
8 * are permitted provided that the following conditions are met:
9 *
10 * * Redistributions of source code must retain the above copyright notice,
11 * this list of conditions and the following disclaimer.
12 * * Redistributions in binary form must reproduce the above copyright notice,
13 * this list of conditions and the following disclaimer in the documentation
14 * and/or other materials provided with the distribution.
15 * * Neither the name of Poly2Tri nor the names of its contributors may be
16 * used to endorse or promote products derived from this software without specific
17 * prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
20 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
21 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
22 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
23 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
24 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
25 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
26 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
27 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
28 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
29 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 */
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
56 /**
57 * Forumla to calculate signed area<br>
58 * Positive if CCW<br>
59 * Negative if CW<br>
60 * 0 if collinear<br>
61 * <pre>
62 * A[P1,P2,P3] = (x1*y2 - y1*x2) + (x2*y3 - y2*x3) + (x3*y1 - y3*x1)
63 * = (x1-x3)*(y2-y3) - (y1-y3)*(x2-x3)
64 * </pre>
65 */
Orient2d(const Point & pa,const Point & pb,const Point & pc)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
InScanArea(const Point & pa,const Point & pb,const Point & pc,const Point & pd)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
130