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).
      Parameters:
      nodes - Collection of nodes

    • 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)
      Find coordinate.
      Parameters:
      coord - Coordinate to find
      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.
      Parameters:
      edgesToAdd - Set of edges to add to the graph

    • 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)
      Parameters:
      e - Edge
      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
      Parameters:
      p0 - first coordinate to match
      p1 - second coordinate to match
      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
      Parameters:
      p0 - Starting coordinate
      p1 - Coordinate used to establish direction
      Returns:
      matching edge, if found null if the edge was not found

    • printEdges

      public void printEdges(PrintStream out)