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CentralEndpointIntersector.h
1 /**********************************************************************
2 *
3 * GEOS - Geometry Engine Open Source
4 * http://geos.osgeo.org
5 *
6 * Copyright (C) 2006 Refractions Research Inc.
7 *
8 * This is free software; you can redistribute and/or modify it under
9 * the terms of the GNU Lesser General Public Licence as published
10 * by the Free Software Foundation.
11 * See the COPYING file for more information.
12 *
13 **********************************************************************
14 *
15 * Last port: algorithm/CentralEndpointIntersector.java rev. 1.1
16 *
17 **********************************************************************/
18
19 #ifndef GEOS_ALGORITHM_CENTRALENDPOINTINTERSECTOR_H
20 #define GEOS_ALGORITHM_CENTRALENDPOINTINTERSECTOR_H
21
22 #include <geos/export.h>
23 #include <geos/geom/Coordinate.h>
24
25 #include <string>
26 #include <limits>
27
28 #ifdef _MSC_VER
29 #pragma warning(push)
30 #pragma warning(disable: 4251) // warning C4251: needs to have dll-interface to be used by clients of class
31 #endif
32
33 // Forward declarations
34 namespace geos {
35 namespace geom {
36 //class PrecisionModel;
37 }
38 }
39
40 namespace geos {
41 namespace algorithm { // geos::algorithm
42
62 class GEOS_DLL CentralEndpointIntersector {
63
64 public:
65
66 static const geom::Coordinate& getIntersection(const geom::Coordinate& p00,
67 const geom::Coordinate& p01, const geom::Coordinate& p10,
68 const geom::Coordinate& p11)
69 {
70 CentralEndpointIntersector intor(p00, p01, p10, p11);
71 return intor.getIntersection();
72 }
73
74 CentralEndpointIntersector(const geom::Coordinate& p00,
75 const geom::Coordinate& p01,
76 const geom::Coordinate& p10,
77 const geom::Coordinate& p11)
78 :
79 _pts(4)
80 {
81 _pts[0]=p00;
82 _pts[1]=p01;
83 _pts[2]=p10;
84 _pts[3]=p11;
85 compute();
86 }
87
88 const geom::Coordinate& getIntersection() const
89 {
90 return _intPt;
91 }
92
93
94 private:
95
96 // This is likely overkill.. we'll be allocating heap
97 // memory at every call !
98 std::vector<geom::Coordinate> _pts;
99
100 geom::Coordinate _intPt;
101
102 void compute()
103 {
104 geom::Coordinate centroid = average(_pts);
105 _intPt = findNearestPoint(centroid, _pts);
106 }
107
108 static geom::Coordinate average(
109 const std::vector<geom::Coordinate>& pts)
110 {
111 geom::Coordinate avg(0, 0);
112 size_t n = pts.size();
113 if ( ! n ) return avg;
114 for (std::size_t i=0; i<n; ++i)
115 {
116 avg.x += pts[i].x;
117 avg.y += pts[i].y;
118 }
119 avg.x /= n;
120 avg.y /= n;
121 return avg;
122 }
123
134 geom::Coordinate findNearestPoint(const geom::Coordinate& p,
135 const std::vector<geom::Coordinate>& pts) const
136 {
137 double minDist = std::numeric_limits<double>::max();
138 geom::Coordinate result = geom::Coordinate::getNull();
139 for (std::size_t i = 0, n=pts.size(); i < n; ++i) {
140 double dist = p.distance(pts[i]);
141 if (dist < minDist) {
142 minDist = dist;
143 result = pts[i];
144 }
145 }
146 return result;
147 }
148 };
149
150 } // namespace geos::algorithm
151 } // namespace geos
152
153 #ifdef _MSC_VER
154 #pragma warning(pop)
155 #endif
156
157 #endif // GEOS_ALGORITHM_CENTRALENDPOINTINTERSECTOR_H