include/geos/geomgraph/EdgeEnd.h

   1 /**********************************************************************
   2  *
   3  * GEOS - Geometry Engine Open Source
   4  * http://geos.refractions.net
   5  *
   6  * Copyright (C) 2011 Sandro Santilli <strk@keybit.net>
   7  * Copyright (C) 2005-2006 Refractions Research Inc.
   8  * Copyright (C) 2001-2002 Vivid Solutions Inc.
   9  *
  10  * This is free software; you can redistribute and/or modify it under
  11  * the terms of the GNU Lesser General Public Licence as published
  12  * by the Free Software Foundation.
  13  * See the COPYING file for more information.
  14  *
  15  **********************************************************************
  16  *
  17  * Last port: geomgraph/EdgeEnd.java r428 (JTS-1.12+)
  18  *
  19  **********************************************************************/
  20
  21
  22 #ifndef GEOS_GEOMGRAPH_EDGEEND_H
  23 #define GEOS_GEOMGRAPH_EDGEEND_H
  24
  25 #include <geos/export.h>
  26 #include <geos/geom/Coordinate.h>  // for p0,p1
  27 #include <geos/geomgraph/Label.h>  // for composition
  28 #include <geos/inline.h>
  29
  30 #include <string>
  31
  32 // Forward declarations
  33 namespace geos {
  34         namespace algorithm {
  35                 class BoundaryNodeRule;
  36         }
  37         namespace geomgraph {
  38                 class Edge;
  39                 class Node;
  40         }
  41 }
  42
  43 namespace geos {
  44 namespace geomgraph { // geos.geomgraph
  45
  46 /** \brief
  47  * Models the end of an edge incident on a node.
  48  *
  49  * EdgeEnds have a direction
  50  * determined by the direction of the ray from the initial
  51  * point to the next point.
  52  * EdgeEnds are comparable under the ordering
  53  * "a has a greater angle with the x-axis than b".
  54  * This ordering is used to sort EdgeEnds around a node.
  55  */
  56 class GEOS_DLL EdgeEnd {
  57
  58 public:
  59
  60         friend std::ostream& operator<< (std::ostream&, const EdgeEnd&);
  61
  62         EdgeEnd();
  63
  64         virtual ~EdgeEnd() {}
  65
  66         /**
  67          * NOTES:
  68          *  - Copies the given Label
  69          *  - keeps a pointer to given Edge, make sure it's
  70          *    not deleted before the EdgeEnd.
  71          *  - copies given Coordinates (maybe we should avoid that)
  72          */
  73         EdgeEnd(Edge* newEdge, const geom::Coordinate& newP0,
  74                         const geom::Coordinate& newP1,
  75                         const Label& newLabel);
  76
  77         /**
  78          * NOTES:
  79          *  - keeps a pointer to given Edge, make sure it's
  80          *    not deleted before the EdgeEnd.
  81          *  - copies given Coordinates (maybe we should avoid that)
  82          */
  83         EdgeEnd(Edge* newEdge, const geom::Coordinate& newP0,
  84                         const geom::Coordinate& newP1);
  85
  86         Edge* getEdge() { return edge; }
  87         //virtual Edge* getEdge() { return edge; }
  88
  89         Label& getLabel() { return label; }
  90
  91         const Label& getLabel() const { return label; }
  92
  93         virtual geom::Coordinate& getCoordinate();
  94
  95         virtual geom::Coordinate& getDirectedCoordinate();
  96
  97         virtual int getQuadrant();
  98
  99         virtual double getDx();
 100
 101         virtual double getDy();
 102
 103         virtual void setNode(Node* newNode);
 104
 105         virtual Node* getNode();
 106
 107         virtual int compareTo(const EdgeEnd *e) const;
 108
 109         /**
 110          * Implements the total order relation:
 111          *
 112          *    a has a greater angle with the positive x-axis than b
 113          *
 114          * Using the obvious algorithm of simply computing the angle
 115          * is not robust, since the angle calculation is obviously
 116          * susceptible to roundoff.
 117          * A robust algorithm is:
 118          * - first compare the quadrant.  If the quadrants
 119          *   are different, it it trivial to determine which vector
 120          *   is "greater".
 121          * - if the vectors lie in the same quadrant, the
 122          *   computeOrientation function can be used to decide
 123          *   the relative orientation of the vectors.
 124          */
 125         virtual int compareDirection(const EdgeEnd *e) const;
 126
 127         virtual void computeLabel(const algorithm::BoundaryNodeRule& bnr);
 128
 129         virtual std::string print();
 130
 131 protected:
 132
 133         Edge* edge;// the parent edge of this edge end
 134
 135         Label label;
 136
 137         EdgeEnd(Edge* newEdge);
 138
 139         virtual void init(const geom::Coordinate& newP0,
 140                         const geom::Coordinate& newP1);
 141
 142 private:
 143
 144         /// the node this edge end originates at
 145         Node* node;
 146
 147         /// points of initial line segment. FIXME: do we need a copy here ?
 148         geom::Coordinate p0, p1;
 149
 150         /// the direction vector for this edge from its starting point
 151         double dx, dy;
 152
 153         int quadrant;
 154 };
 155
 156 std::ostream& operator<< (std::ostream&, const EdgeEnd&);
 157
 158 struct GEOS_DLL  EdgeEndLT {
 159         bool operator()(const EdgeEnd *s1, const EdgeEnd *s2) const {
 160                 return s1->compareTo(s2)<0;
 161         }
 162 };
 163
 164 } // namespace geos.geomgraph
 165 } // namespace geos
 166
 167 //#ifdef GEOS_INLINE
 168 //# include "geos/geomgraph/EdgeEnd.inl"
 169 //#endif
 170
 171 #endif // ifndef GEOS_GEOMGRAPH_EDGEEND_H