/*
* Copyright (c) 2016 Vivid Solutions.
*
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* and Eclipse Distribution License v. 1.0 which accompanies this distribution.
* The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
* and the Eclipse Distribution License is available at
*
* http://www.eclipse.org/org/documents/edl-v10.php.
*/
package org.locationtech.jts.operation.relate;
/**
* @version 1.7
*/
import java.util.Iterator;
import java.util.List;
import org.locationtech.jts.geom.Location;
import org.locationtech.jts.geomgraph.Edge;
import org.locationtech.jts.geomgraph.EdgeEnd;
import org.locationtech.jts.geomgraph.EdgeIntersection;
import org.locationtech.jts.geomgraph.GeometryGraph;
import org.locationtech.jts.geomgraph.Node;
import org.locationtech.jts.geomgraph.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.
*
* @version 1.7
*/
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);
}
}
}