src/geomgraph/Quadrant.cpp

   1 /**********************************************************************
   2  *
   3  * GEOS - Geometry Engine Open Source
   4  * http://geos.osgeo.org
   5  *
   6  * Copyright (C) 2001-2002 Vivid Solutions 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: geomgraph/Quadrant.java rev. 1.8 (JTS-1.10)
  16  *
  17  **********************************************************************/
  18
  19 #include <sstream>
  20
  21 #include <geos/geomgraph/Quadrant.h>
  22 #include <geos/util/IllegalArgumentException.h>
  23
  24 #include <geos/geom/Coordinate.h>
  25
  26 using namespace std;
  27 using namespace geos::geom;
  28
  29 namespace geos {
  30 namespace geomgraph { // geos.geomgraph
  31
  32 /* public static */
  33 int
  34 Quadrant::quadrant(double dx, double dy)
  35 {
  36         if (dx == 0.0 && dy == 0.0) {
  37                 ostringstream s;
  38                 s<<"Cannot compute the quadrant for point ";
  39                 s<<"("<<dx<<","<<dy<<")"<<endl;
  40                 throw util::IllegalArgumentException(s.str());
  41         }
  42         if (dx >= 0) {
  43                 if (dy >= 0)
  44                         return NE;
  45                 else
  46                         return SE;
  47         } else {
  48                 if (dy >= 0)
  49                         return NW;
  50                 else
  51                         return SW;
  52         }
  53 }
  54
  55 /* public static */
  56 int
  57 Quadrant::quadrant(const Coordinate& p0, const Coordinate& p1)
  58 {
  59         if (p1.x == p0.x && p1.y == p0.y)
  60         {
  61                 throw util::IllegalArgumentException("Cannot compute the quadrant for two identical points " + p0.toString());
  62         }
  63
  64         if (p1.x >= p0.x) {
  65                 if (p1.y >= p0.y)
  66                         return NE;
  67                 else
  68                         return SE;
  69         }
  70         else {
  71                 if (p1.y >= p0.y)
  72                         return NW;
  73                 else
  74                         return SW;
  75         }
  76 }
  77
  78 /* public static */
  79 bool
  80 Quadrant::isOpposite(int quad1, int quad2)
  81 {
  82         if (quad1==quad2) return false;
  83         int diff=(quad1-quad2+4)%4;
  84         // if quadrants are not adjacent, they are opposite
  85         if (diff==2) return true;
  86         return false;
  87 }
  88
  89 /* public static */
  90 int
  91 Quadrant::commonHalfPlane(int quad1, int quad2)
  92 {
  93         // if quadrants are the same they do not determine a unique
  94         // common halfplane.
  95         // Simply return one of the two possibilities
  96         if (quad1==quad2) return quad1;
  97         int diff=(quad1-quad2+4)%4;
  98         // if quadrants are not adjacent, they do not share a common halfplane
  99         if (diff==2) return -1;
 100         //
 101         int min=(quad1<quad2)? quad1:quad2;
 102         int max=(quad1>quad2)? quad1:quad2;
 103         // for this one case, the righthand plane is NOT the minimum index;
 104         if (min==0 && max==3) return 3;
 105         // in general, the halfplane index is the minimum of the two
 106         // adjacent quadrants
 107         return min;
 108 }
 109
 110 /* public static */
 111 bool
 112 Quadrant::isInHalfPlane(int quad, int halfPlane)
 113 {
 114         if (halfPlane==SE) {
 115                 return quad==SE || quad==SW;
 116         }
 117         return quad==halfPlane || quad==halfPlane+1;
 118 }
 119
 120 /* public static */
 121 bool
 122 Quadrant::isNorthern(int quad)
 123 {
 124         return quad==NE || quad==NW;
 125 }
 126
 127 } // namespace geos.geomgraph
 128 } // namespace geos
 129
 130 /**********************************************************************
 131  * $Log$
 132  * Revision 1.10  2006/03/15 17:16:29  strk
 133  * streamlined headers inclusion
 134  *
 135  * Revision 1.9  2006/03/09 16:46:47  strk
 136  * geos::geom namespace definition, first pass at headers split
 137  *
 138  * Revision 1.8  2006/03/06 19:40:46  strk
 139  * geos::util namespace. New GeometryCollection::iterator interface, many cleanups.
 140  *
 141  * Revision 1.7  2006/03/03 10:46:21  strk
 142  * Removed 'using namespace' from headers, added missing headers in .cpp files, removed useless includes in headers (bug#46)
 143  *
 144  * Revision 1.6  2006/02/19 19:46:49  strk
 145  * Packages <-> namespaces mapping for most GEOS internal code (uncomplete, but working). Dir-level libs for index/ subdirs.
 146  *
 147  * Revision 1.5  2006/02/09 15:52:47  strk
 148  * GEOSException derived from std::exception; always thrown and cought by const ref.
 149  *
 150  * Revision 1.4  2005/02/05 05:44:47  strk
 151  * Changed geomgraph nodeMap to use Coordinate pointers as keys, reduces
 152  * lots of other Coordinate copies.
 153  *
 154  * Revision 1.3  2005/01/28 09:47:51  strk
 155  * Replaced sprintf uses with ostringstream.
 156  *
 157  * Revision 1.2  2004/07/02 13:28:26  strk
 158  * Fixed all #include lines to reflect headers layout change.
 159  * Added client application build tips in README.
 160  *
 161  * Revision 1.1  2004/03/19 09:48:45  ybychkov
 162  * "geomgraph" and "geomgraph/indexl" upgraded to JTS 1.4
 163  *
 164  * Revision 1.10  2003/11/07 01:23:42  pramsey
 165  * Add standard CVS headers licence notices and copyrights to all cpp and h
 166  * files.
 167  *
 168  *
 169  **********************************************************************/
 170