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# CentralEndpointIntersector.h

    00001 /**********************************************************************
    00002  * $Id: CentralEndpointIntersector.h 3255 2011-03-01 17:56:10Z mloskot $
    00003  *
    00004  * GEOS - Geometry Engine Open Source
    00005  * http://geos.refractions.net
    00006  *
    00007  * Copyright (C) 2006 Refractions Research Inc.
    00008  *
    00009  * This is free software; you can redistribute and/or modify it under
    00010  * the terms of the GNU Lesser General Public Licence as published
    00011  * by the Free Software Foundation.
    00012  * See the COPYING file for more information.
    00013  *
    00014  **********************************************************************
    00015  *
    00016  * Last port: algorithm/CentralEndpointIntersector.java rev. 1.1
    00017  *
    00018  **********************************************************************/
    00019
    00020 #ifndef GEOS_ALGORITHM_CENTRALENDPOINTINTERSECTOR_H
    00021 #define GEOS_ALGORITHM_CENTRALENDPOINTINTERSECTOR_H
    00022
    00023 #include <geos/export.h>
    00024 #include <geos/geom/Coordinate.h>
    00025
    00026 #include <string>
    00027 #include <limits>
    00028
    00029 #ifdef _MSC_VER
    00030 #pragma warning(push)
    00031 #pragma warning(disable: 4251) // warning C4251: needs to have dll-interface to be used by clients of class
    00032 #endif
    00033
    00034 // Forward declarations
    00035 namespace geos {
    00036         namespace geom {
    00037                 //class PrecisionModel;
    00038         }
    00039 }
    00040
    00041 namespace geos {
    00042 namespace algorithm { // geos::algorithm
    00043
    00063 class GEOS_DLL CentralEndpointIntersector {
    00064
    00065 public:
    00066
    00067         static const geom::Coordinate& getIntersection(const geom::Coordinate& p00,
    00068                         const geom::Coordinate& p01, const geom::Coordinate& p10,
    00069                         const geom::Coordinate& p11)
    00070         {
    00071                 CentralEndpointIntersector intor(p00, p01, p10, p11);
    00072                 return intor.getIntersection();
    00073         }
    00074
    00075         CentralEndpointIntersector(const geom::Coordinate& p00,
    00076                         const geom::Coordinate& p01,
    00077                         const geom::Coordinate& p10,
    00078                         const geom::Coordinate& p11)
    00079                 :
    00080                 _pts(4)
    00081         {
    00082                 _pts[0]=p00;
    00083                 _pts[1]=p01;
    00084                 _pts[2]=p10;
    00085                 _pts[3]=p11;
    00086                 compute();
    00087         }
    00088
    00089         const geom::Coordinate& getIntersection() const
    00090         {
    00091                 return _intPt;
    00092         }
    00093
    00094
    00095 private:
    00096
    00097         // This is likely overkill.. we'll be allocating heap
    00098         // memory at every call !
    00099         std::vector<geom::Coordinate> _pts;
    00100
    00101         geom::Coordinate _intPt;
    00102
    00103         void compute()
    00104         {
    00105                 geom::Coordinate centroid = average(_pts);
    00106                 _intPt = findNearestPoint(centroid, _pts);
    00107         }
    00108
    00109         static geom::Coordinate average(
    00110                         const std::vector<geom::Coordinate>& pts)
    00111         {
    00112                 geom::Coordinate avg(0, 0);
    00113                 size_t n = pts.size();
    00114                 if ( ! n ) return avg;
    00115                 for (std::size_t i=0; i<n; ++i)
    00116                 {
    00117                         avg.x += pts[i].x;
    00118                         avg.y += pts[i].y;
    00119                 }
    00120                 avg.x /= n;
    00121                 avg.y /= n;
    00122                 return avg;
    00123         }
    00124
    00135         geom::Coordinate findNearestPoint(const geom::Coordinate& p,
    00136                         const std::vector<geom::Coordinate>& pts) const
    00137         {
    00138                 double minDist = std::numeric_limits<double>::max();
    00139                 geom::Coordinate result = geom::Coordinate::getNull();
    00140                 for (std::size_t i = 0, n=pts.size(); i < n; ++i) {
    00141                         double dist = p.distance(pts[i]);
    00142                         if (dist < minDist) {
    00143                                 minDist = dist;
    00144                                 result = pts[i];
    00145                         }
    00146                 }
    00147                 return result;
    00148         }
    00149 };
    00150
    00151 } // namespace geos::algorithm
    00152 } // namespace geos
    00153
    00154 #ifdef _MSC_VER
    00155 #pragma warning(pop)
    00156 #endif
    00157
    00158 #endif // GEOS_ALGORITHM_CENTRALENDPOINTINTERSECTOR_H
    00159
    00160 /**********************************************************************
    00161  * $Log$
    00162  **********************************************************************/
    00163