src/noding/SegmentIntersectionDetector.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
  16 #include <geos/noding/SegmentIntersectionDetector.h>
  17 #include <geos/noding/SegmentIntersector.h>
  18 #include <geos/algorithm/LineIntersector.h>
  19 #include <geos/geom/Coordinate.h>
  20 #include <geos/geom/CoordinateArraySequence.h>
  21 #include <geos/noding/SegmentString.h>
  22
  23
  24 namespace geos {
  25 namespace noding { // geos::noding
  26
  27
  28
  29 void
  30 SegmentIntersectionDetector::
  31 processIntersections(
  32         noding::SegmentString * e0, int segIndex0,
  33         noding::SegmentString * e1, int segIndex1 )
  34 {
  35         // don't bother intersecting a segment with itself
  36         if (e0 == e1 && segIndex0 == segIndex1) return;
  37
  38         const geom::Coordinate & p00 = (*e0->getCoordinates())[ segIndex0 ];
  39         const geom::Coordinate & p01 = (*e0->getCoordinates())[ segIndex0 + 1 ];
  40         const geom::Coordinate & p10 = (*e1->getCoordinates())[ segIndex1 ];
  41         const geom::Coordinate & p11 = (*e1->getCoordinates())[ segIndex1 + 1 ];
  42
  43         li->computeIntersection( p00, p01, p10, p11);
  44
  45         if (li->hasIntersection())
  46         {
  47                 // record intersection info
  48                 _hasIntersection = true;
  49
  50                 bool isProper = li->isProper();
  51
  52                 if (isProper)
  53                         _hasProperIntersection = true;
  54                 else
  55                         _hasNonProperIntersection = true;
  56
  57                 // If this is the kind of intersection we are searching for
  58                 // OR no location has yet been recorded
  59                 // save the location data
  60                 bool saveLocation = true;
  61
  62                 if (findProper && !isProper)
  63                         saveLocation = false;
  64
  65                 if (!intPt || saveLocation)
  66                 {
  67                         // record intersection location (approximate)
  68                         intPt = &li->getIntersection(0);
  69
  70                         delete intSegments;
  71
  72                         // record intersecting segments
  73                         intSegments = new geom::CoordinateArraySequence();
  74                         intSegments->add( p00, true);
  75                         intSegments->add( p01, true);
  76                         intSegments->add( p10, true);
  77                         intSegments->add( p11, true);
  78                 }
  79         }
  80 }
  81
  82
  83 } // geos::noding
  84 } // geos
  85
  86 /**********************************************************************
  87  * $Log$
  88  *
  89  **********************************************************************/