/*
* GeoTools - The Open Source Java GIS Toolkit
* http://geotools.org
*
* (C) 2001-2006 Vivid Solutions
* (C) 2001-2008, Open Source Geospatial Foundation (OSGeo)
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation;
* version 2.1 of the License.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*/
package org.geotools.geometry.iso.operation.relate;
/**
* @version 1.7.2
*/
import java.util.Iterator;
import java.util.List;
import org.geotools.geometry.iso.topograph2D.Edge;
import org.geotools.geometry.iso.topograph2D.EdgeEnd;
import org.geotools.geometry.iso.topograph2D.EdgeIntersection;
import org.geotools.geometry.iso.topograph2D.GeometryGraph;
import org.geotools.geometry.iso.topograph2D.Location;
import org.geotools.geometry.iso.topograph2D.Node;
import org.geotools.geometry.iso.topograph2D.NodeMap;
/**
* Implements the simple graph of Nodes and EdgeEnd which is all that is
* required to determine topological relationships between Geometries. Also
* supports building a topological graph of a single Geometry, to allow
* verification of valid topology.
* <p>
* It is <b>not</b> necessary to create a fully linked PlanarGraph to determine
* relationships, since it is sufficient to know how the Geometries interact
* locally around the nodes. In fact, this is not even feasible, since it is not
* possible to compute exact intersection points, and hence the topology around
* those nodes cannot be computed robustly. The only Nodes that are created are
* for improper intersections; that is, nodes which occur at existing vertices
* of the Geometries. Proper intersections (e.g. ones which occur between the
* interior of line segments) have their topology determined implicitly, without
* creating a Node object to represent them.
*
*
*
*
*
* @source $URL$
* @version 1.7.2
*/
public class RelateNodeGraph {
private NodeMap nodes = new NodeMap(new RelateNodeFactory());
public RelateNodeGraph() {
}
public Iterator getNodeIterator() {
return nodes.iterator();
}
public void build(GeometryGraph geomGraph) {
// compute nodes for intersections between previously noded edges
computeIntersectionNodes(geomGraph, 0);
/**
* Copy the labelling for the nodes in the parent Geometry. These
* override any labels determined by intersections.
*/
copyNodesAndLabels(geomGraph, 0);
/**
* Build EdgeEnds for all intersections.
*/
EdgeEndBuilder eeBuilder = new EdgeEndBuilder();
List eeList = eeBuilder.computeEdgeEnds(geomGraph.getEdgeIterator());
insertEdgeEnds(eeList);
// Debug.println("==== NodeList ===");
// Debug.print(nodes);
}
/**
* Insert nodes for all intersections on the edges of a Geometry. Label the
* created nodes the same as the edge label if they do not already have a
* label. This allows nodes created by either self-intersections or mutual
* intersections to be labelled. Endpoint nodes will already be labelled
* from when they were inserted.
* <p>
* Precondition: edge intersections have been computed.
*/
public void computeIntersectionNodes(GeometryGraph geomGraph, int argIndex) {
for (Iterator edgeIt = geomGraph.getEdgeIterator(); edgeIt.hasNext();) {
Edge e = (Edge) edgeIt.next();
int eLoc = e.getLabel().getLocation(argIndex);
for (Iterator eiIt = e.getEdgeIntersectionList().iterator(); eiIt
.hasNext();) {
EdgeIntersection ei = (EdgeIntersection) eiIt.next();
RelateNode n = (RelateNode) nodes.addNode(ei.coord);
if (eLoc == Location.BOUNDARY)
n.setLabelBoundary(argIndex);
else {
if (n.getLabel().isNull(argIndex))
n.setLabel(argIndex, Location.INTERIOR);
}
// Debug.println(n);
}
}
}
/**
* Copy all nodes from an arg geometry into this graph. The node label in
* the arg geometry overrides any previously computed label for that
* argIndex. (E.g. a node may be an intersection node with a computed label
* of BOUNDARY, but in the original arg Geometry it is actually in the
* interior due to the Boundary Determination Rule)
*/
public void copyNodesAndLabels(GeometryGraph geomGraph, int argIndex) {
for (Iterator nodeIt = geomGraph.getNodeIterator(); nodeIt.hasNext();) {
Node graphNode = (Node) nodeIt.next();
Node newNode = nodes.addNode(graphNode.getCoordinate());
newNode.setLabel(argIndex, graphNode.getLabel().getLocation(
argIndex));
// node.print(System.out);
}
}
public void insertEdgeEnds(List ee) {
for (Iterator i = ee.iterator(); i.hasNext();) {
EdgeEnd e = (EdgeEnd) i.next();
nodes.add(e);
}
}
}