Class PlanarGraph

java.lang.Object
org.locationtech.jts.geomgraph.PlanarGraph
Direct Known Subclasses:
GeometryGraph

public class PlanarGraph extends Object
The computation of the IntersectionMatrix relies on the use of a structure called a "topology graph". The topology graph contains nodes and edges corresponding to the nodes and line segments of a Geometry. Each node and edge in the graph is labeled with its topological location relative to the source geometry.

Note that there is no requirement that points of self-intersection be a vertex. Thus to obtain a correct topology graph, Geometrys must be self-noded before constructing their graphs.

Two fundamental operations are supported by topology graphs:

  • Computing the intersections between all the edges and nodes of a single graph
  • Computing the intersections between the edges and nodes of two different graphs
Version:
1.7
  • Field Details

    • edges

      protected List edges
    • nodes

      protected NodeMap nodes
    • edgeEndList

      protected List edgeEndList
  • Constructor Details

    • PlanarGraph

      public PlanarGraph(NodeFactory nodeFact)
    • PlanarGraph

      public PlanarGraph()
  • Method Details

    • linkResultDirectedEdges

      public static void linkResultDirectedEdges(Collection nodes)
      For nodes in the Collection, link the DirectedEdges at the node that are in the result. This allows clients to link only a subset of nodes in the graph, for efficiency (because they know that only a subset is of interest).
    • getEdgeIterator

      public Iterator getEdgeIterator()
    • getEdgeEnds

      public Collection getEdgeEnds()
    • isBoundaryNode

      public boolean isBoundaryNode(int geomIndex, Coordinate coord)
    • insertEdge

      protected void insertEdge(Edge e)
    • add

      public void add(EdgeEnd e)
    • getNodeIterator

      public Iterator getNodeIterator()
    • getNodes

      public Collection getNodes()
    • addNode

      public Node addNode(Node node)
    • addNode

      public Node addNode(Coordinate coord)
    • find

      public Node find(Coordinate coord)
      Returns:
      the node if found; null otherwise
    • addEdges

      public void addEdges(List edgesToAdd)
      Add a set of edges to the graph. For each edge two DirectedEdges will be created. DirectedEdges are NOT linked by this method.
    • linkResultDirectedEdges

      public void linkResultDirectedEdges()
      Link the DirectedEdges at the nodes of the graph. This allows clients to link only a subset of nodes in the graph, for efficiency (because they know that only a subset is of interest).
    • linkAllDirectedEdges

      public void linkAllDirectedEdges()
      Link the DirectedEdges at the nodes of the graph. This allows clients to link only a subset of nodes in the graph, for efficiency (because they know that only a subset is of interest).
    • findEdgeEnd

      public EdgeEnd findEdgeEnd(Edge e)
      Returns the EdgeEnd which has edge e as its base edge (MD 18 Feb 2002 - this should return a pair of edges)
      Returns:
      the edge, if found null if the edge was not found
    • findEdge

      public Edge findEdge(Coordinate p0, Coordinate p1)
      Returns the edge whose first two coordinates are p0 and p1
      Returns:
      the edge, if found null if the edge was not found
    • findEdgeInSameDirection

      public Edge findEdgeInSameDirection(Coordinate p0, Coordinate p1)
      Returns the edge which starts at p0 and whose first segment is parallel to p1
      Returns:
      the edge, if found null if the edge was not found
    • matchInSameDirection

      private boolean matchInSameDirection(Coordinate p0, Coordinate p1, Coordinate ep0, Coordinate ep1)
      The coordinate pairs match if they define line segments lying in the same direction. E.g. the segments are parallel and in the same quadrant (as opposed to parallel and opposite!).
    • printEdges

      public void printEdges(PrintStream out)
    • debugPrint

      void debugPrint(Object o)
    • debugPrintln

      void debugPrintln(Object o)