# geos::geomgraph::PlanarGraph Class Reference

Represents a directed graph which is embeddable in a planar surface. More...

`#include <PlanarGraph.h>`

Inherited by geos::geomgraph::GeometryGraph.

List of all members.

## Public Member Functions

| PlanarGraph (const NodeFactory &nodeFact)
virtual std::vector< Edge * > ::iterator | getEdgeIterator ()
virtual std::vector< EdgeEnd * > * | getEdgeEnds ()
virtual bool | isBoundaryNode (int geomIndex, const geom::Coordinate &coord)
virtual void | add (EdgeEnd *e)
virtual NodeMap::iterator | getNodeIterator ()
virtual void | getNodes (std::vector< Node * > &)
virtual Node * | addNode (Node *node)
virtual Node * | addNode (const geom::Coordinate &coord)
virtual Node * | find (geom::Coordinate &coord)

Returns:
  the node if found; null otherwise

virtual void | addEdges (const std::vector< Edge * > &edgesToAdd)
| Add a set of edges to the graph. For each edge two DirectedEdges will be created. DirectedEdges are NOT linked by this method.
virtual void | linkResultDirectedEdges ()
virtual void | linkAllDirectedEdges ()
virtual 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).
virtual Edge * | findEdge (const geom::Coordinate &p0, const geom::Coordinate &p1)
| Returns the edge whose first two coordinates are p0 and p1.
virtual Edge * | findEdgeInSameDirection (const geom::Coordinate &p0, const geom::Coordinate &p1)
| Returns the edge which starts at p0 and whose first segment is parallel to p1.
virtual std::string | printEdges ()
virtual NodeMap * | getNodeMap ()

## Static Public Member Functions

static void | linkResultDirectedEdges (std::vector< Node * >::iterator start, std::vector< Node * >::iterator end)
| For nodes in the vector, link the DirectedEdges at the node that are in the result.

## Protected Member Functions

virtual void | insertEdge (Edge *e)

## Protected Attributes

std::vector< Edge * > * | edges
NodeMap * | nodes
std::vector< EdgeEnd * > * | edgeEndList

## Detailed Description

Represents a directed graph which is embeddable in a planar surface.

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, Geometry objects 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

## Member Function Documentation

static void geos::geomgraph::PlanarGraph::linkResultDirectedEdges | ( | std::vector< Node * >::iterator | start,
|  | std::vector< Node * >::iterator | end |
| ) |  |  | `[static]`

For nodes in the vector, 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).

virtual EdgeEnd* geos::geomgraph::PlanarGraph::findEdgeEnd | ( | Edge * | e | ) | `[virtual]`

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

virtual Edge* geos::geomgraph::PlanarGraph::findEdge | ( | const geom::Coordinate & | p0,
|  | const geom::Coordinate & | p1 |
| ) |  |  | `[virtual]`

Returns the edge whose first two coordinates are p0 and p1.

Returns:
  the edge, if found `null` if the edge was not found

virtual Edge* geos::geomgraph::PlanarGraph::findEdgeInSameDirection | ( | const geom::Coordinate & | p0,
|  | const geom::Coordinate & | p1 |
| ) |  |  | `[virtual]`

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

The documentation for this class was generated from the following file:

- geomgraph/PlanarGraph.h