com.vividsolutions.jts.geomgraph

Class 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

    • Field Detail

      • edges

        protected List edges

      • edgeEndList

        protected List edgeEndList

    • Constructor Detail

      • PlanarGraph

        public PlanarGraph(NodeFactory nodeFact)

      • PlanarGraph

        public PlanarGraph()

    • Method Detail

      • 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()

      • isBoundaryNode

        public boolean isBoundaryNode(int geomIndex,
                              Coordinate coord)

      • insertEdge

        protected void insertEdge(Edge e)

      • getNodeIterator

        public Iterator getNodeIterator()

      • addNode

        public Node addNode(Node node)

      • 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