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 #ifndef _USE_MATH_DEFINES
37 #define _USE_MATH_DEFINES
38 #endif
39
40 #include "shapes.h"
41
42 #include <cmath>
43 #include <exception>
44
45 // C99 removes M_PI from math.h
46 #ifndef M_PI
47 #define M_PI 3.14159265358979323846264338327
48 #endif
49
50 namespace p2t {
51
52 const double PI_3div4 = 3 * M_PI / 4;
53 const double PI_div2 = 1.57079632679489661923;
54 const double EPSILON = 1e-12;
55
56 enum Orientation { CW, CCW, COLLINEAR };
57
58 /**
59 * Forumla to calculate signed area<br>
60 * Positive if CCW<br>
61 * Negative if CW<br>
62 * 0 if collinear<br>
63 * <pre>
64 * A[P1,P2,P3] = (x1*y2 - y1*x2) + (x2*y3 - y2*x3) + (x3*y1 - y3*x1)
65 * = (x1-x3)*(y2-y3) - (y1-y3)*(x2-x3)
66 * </pre>
67 */
Orient2d(const Point & pa,const Point & pb,const Point & pc)68 Orientation Orient2d(const Point& pa, const Point& pb, const Point& pc)
69 {
70 double detleft = (pa.x - pc.x) * (pb.y - pc.y);
71 double detright = (pa.y - pc.y) * (pb.x - pc.x);
72 double val = detleft - detright;
73 if (val > -EPSILON && val < EPSILON) {
74 return COLLINEAR;
75 } else if (val > 0) {
76 return CCW;
77 }
78 return CW;
79 }
80
81 /*
82 bool InScanArea(Point& pa, Point& pb, Point& pc, Point& pd)
83 {
84 double pdx = pd.x;
85 double pdy = pd.y;
86 double adx = pa.x - pdx;
87 double ady = pa.y - pdy;
88 double bdx = pb.x - pdx;
89 double bdy = pb.y - pdy;
90
91 double adxbdy = adx * bdy;
92 double bdxady = bdx * ady;
93 double oabd = adxbdy - bdxady;
94
95 if (oabd <= EPSILON) {
96 return false;
97 }
98
99 double cdx = pc.x - pdx;
100 double cdy = pc.y - pdy;
101
102 double cdxady = cdx * ady;
103 double adxcdy = adx * cdy;
104 double ocad = cdxady - adxcdy;
105
106 if (ocad <= EPSILON) {
107 return false;
108 }
109
110 return true;
111 }
112
113 */
114
InScanArea(const Point & pa,const Point & pb,const Point & pc,const Point & pd)115 bool InScanArea(const Point& pa, const Point& pb, const Point& pc, const Point& pd)
116 {
117 double oadb = (pa.x - pb.x)*(pd.y - pb.y) - (pd.x - pb.x)*(pa.y - pb.y);
118 if (oadb >= -EPSILON) {
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 if (oadc <= EPSILON) {
124 return false;
125 }
126 return true;
127 }
128
129 }
130
131 #endif
132