GEOS 3.14.0dev
Quadrant.h
1/**********************************************************************
2 *
3 * GEOS - Geometry Engine Open Source
4 * http://geos.osgeo.org
5 *
6 * Copyright (C) 2005-2006 Refractions Research Inc.
7 * Copyright (C) 2001-2002 Vivid Solutions Inc.
8 *
9 * This is free software; you can redistribute and/or modify it under
10 * the terms of the GNU Lesser General Public Licence as published
11 * by the Free Software Foundation.
12 * See the COPYING file for more information.
13 *
14 **********************************************************************
15 *
16 * Last port: geom/Quadrant.java rev. 1.8 (JTS-1.10)
17 *
18 **********************************************************************/
19
20
21#pragma once
22
23#include <geos/export.h>
24#include <geos/geom/Quadrant.h>
25#include <geos/geom/Coordinate.h>
26#include <geos/util/IllegalArgumentException.h>
27
28#include <string>
29#include <sstream>
30
31// Forward declarations
32namespace geos {
33namespace geom {
34class Coordinate;
35}
36}
37
38namespace geos {
39namespace geom { // geos.geom
40
52class GEOS_DLL Quadrant {
53
54public:
55
56 static const int NE = 0;
57 static const int NW = 1;
58 static const int SW = 2;
59 static const int SE = 3;
60
67 static int quadrant(double dx, double dy)
68 {
69 if(dx == 0.0 && dy == 0.0) {
70 std::ostringstream s;
71 s << "Cannot compute the quadrant for point ";
72 s << "(" << dx << "," << dy << ")" << std::endl;
73 throw util::IllegalArgumentException(s.str());
74 }
75 if(dx >= 0) {
76 if(dy >= 0) {
77 return NE;
78 }
79 else {
80 return SE;
81 }
82 }
83 else {
84 if(dy >= 0) {
85 return NW;
86 }
87 else {
88 return SW;
89 }
90 }
91 };
92
98 static int quadrant(const geom::CoordinateXY& p0, const geom::CoordinateXY& p1)
99 {
100 if(p1.x == p0.x && p1.y == p0.y) {
101 throw util::IllegalArgumentException("Cannot compute the quadrant for two identical points " + p0.toString());
102 }
103
104 if(p1.x >= p0.x) {
105 if(p1.y >= p0.y) {
106 return NE;
107 }
108 else {
109 return SE;
110 }
111 }
112 else {
113 if(p1.y >= p0.y) {
114 return NW;
115 }
116 else {
117 return SW;
118 }
119 }
120 };
121
125 static bool isOpposite(int quad1, int quad2)
126 {
127 if(quad1 == quad2) {
128 return false;
129 }
130 int diff = (quad1 - quad2 + 4) % 4;
131 // if quadrants are not adjacent, they are opposite
132 if(diff == 2) {
133 return true;
134 }
135 return false;
136 };
137
138 /*
139 * Returns the right-hand quadrant of the halfplane defined by
140 * the two quadrants,
141 * or -1 if the quadrants are opposite, or the quadrant if they
142 * are identical.
143 */
144 static int commonHalfPlane(int quad1, int quad2);
145
150 static bool isInHalfPlane(int quad, int halfPlane);
151
155 static bool isNorthern(int quad)
156 {
157 return quad == NE || quad == NW;
158 };
159
160};
161
162
163} // namespace geos.geom
164} // namespace geos
Utility functions for working with quadrants.
Definition Quadrant.h:52
static int quadrant(double dx, double dy)
Definition Quadrant.h:67
static bool isOpposite(int quad1, int quad2)
Definition Quadrant.h:125
static int quadrant(const geom::CoordinateXY &p0, const geom::CoordinateXY &p1)
Definition Quadrant.h:98
static bool isInHalfPlane(int quad, int halfPlane)
static bool isNorthern(int quad)
Definition Quadrant.h:155
Indicates one or more illegal arguments.
Definition IllegalArgumentException.h:33
Basic namespace for all GEOS functionalities.
Definition geos.h:39