1/*
2 * Poly2Tri Copyright (c) 2009-2010, Poly2Tri Contributors
3 * http://code.google.com/p/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 <exception>
39#include <math.h>
40
41#ifndef M_PI
42#define M_PI (3.14159265358979323846)
43#endif
44
45namespace p2t {
46
47const double PI_3div4 = 3 * M_PI / 4;
48const double PI_div2 = 1.57079632679489661923;
49const double EPSILON = 1e-12;
50
51enum Orientation { CW, CCW, COLLINEAR };
52
53/**
54 * Forumla to calculate signed area<br>
55 * Positive if CCW<br>
56 * Negative if CW<br>
57 * 0 if collinear<br>
58 * <pre>
59 * A[P1,P2,P3] = (x1*y2 - y1*x2) + (x2*y3 - y2*x3) + (x3*y1 - y3*x1)
60 * = (x1-x3)*(y2-y3) - (y1-y3)*(x2-x3)
61 * </pre>
62 */
63Orientation Orient2d(Point& pa, Point& pb, Point& pc)
64{
65 double detleft = (pa.x - pc.x) * (pb.y - pc.y);
66 double detright = (pa.y - pc.y) * (pb.x - pc.x);
67 double val = detleft - detright;
68 if (val > -EPSILON && val < EPSILON) {
69 return COLLINEAR;
70 } else if (val > 0) {
71 return CCW;
72 }
73 return CW;
74}
75
76/*
77bool InScanArea(Point& pa, Point& pb, Point& pc, Point& pd)
78{
79 double pdx = pd.x;
80 double pdy = pd.y;
81 double adx = pa.x - pdx;
82 double ady = pa.y - pdy;
83 double bdx = pb.x - pdx;
84 double bdy = pb.y - pdy;
85
86 double adxbdy = adx * bdy;
87 double bdxady = bdx * ady;
88 double oabd = adxbdy - bdxady;
89
90 if (oabd <= EPSILON) {
91 return false;
92 }
93
94 double cdx = pc.x - pdx;
95 double cdy = pc.y - pdy;
96
97 double cdxady = cdx * ady;
98 double adxcdy = adx * cdy;
99 double ocad = cdxady - adxcdy;
100
101 if (ocad <= EPSILON) {
102 return false;
103 }
104
105 return true;
106}
107
108*/
109
110bool InScanArea(Point& pa, Point& pb, Point& pc, Point& pd)
111{
112 double oadb = (pa.x - pb.x)*(pd.y - pb.y) - (pd.x - pb.x)*(pa.y - pb.y);
113 if (oadb >= -EPSILON) {
114 return false;
115 }
116
117 double oadc = (pa.x - pc.x)*(pd.y - pc.y) - (pd.x - pc.x)*(pa.y - pc.y);
118 if (oadc <= EPSILON) {
119 return false;
120 }
121 return true;
122}
123
124}
125
126#endif
127
128

source code of qtlocation/src/3rdparty/poly2tri/common/utils.h