/// <summary>
///
/// </summary>
/// <param name="startDE"></param>
/// <returns></returns>
private EdgeRing FindEdgeRing(PolygonizeDirectedEdge startDE)
{
PolygonizeDirectedEdge de = startDE;
EdgeRing er = new EdgeRing(_factory);
do
{
er.Add(de);
de.Ring = er;
de = de.Next;
Assert.IsTrue(de != null, "found null DE in ring");
Assert.IsTrue(de == startDE || ! de.IsInRing, "found DE already in ring");
}
while (de != startDE);
return er;
}
/// <summary>
/// Finds all nodes in a maximal edgering which are self-intersection nodes
/// </summary>
/// <param name="startDE"></param>
/// <param name="label"></param>
/// <returns>
/// The list of intersection nodes found,
/// or null if no intersection nodes were found.
/// </returns>
private static IList FindIntersectionNodes(PolygonizeDirectedEdge startDE, long label)
{
PolygonizeDirectedEdge de = startDE;
IList intNodes = null;
do
{
if (de == null) continue;
Node node = de.FromNode;
if (GetDegree(node, label) > 1)
{
if (intNodes == null)
intNodes = new ArrayList();
intNodes.Add(node);
}
de = de.Next;
Assert.IsTrue(de != null, "found null DE in ring");
Assert.IsTrue(de == startDE || !de.IsInRing, "found DE already in ring");
}
while (de != startDE);
return intNodes;
}
/// <summary>
/// Traverse a ring of DirectedEdges, accumulating them into a list.
/// This assumes that all dangling directed edges have been removed
/// from the graph, so that there is always a next dirEdge.
/// </summary>
/// <param name="startDE">The DirectedEdge to start traversing at.</param>
/// <returns>A List of DirectedEdges that form a ring.</returns>
private static IList FindDirEdgesInRing(PolygonizeDirectedEdge startDE)
{
PolygonizeDirectedEdge de = startDE;
IList edges = new ArrayList();
do
{
edges.Add(de);
de = de.Next;
Assert.IsTrue(de != null, "found null DE in ring");
Assert.IsTrue(de == startDE || !de.IsInRing, "found DE already in ring");
}
while (de != startDE);
return edges;
}
/// <summary>
/// Add a <c>LineString</c> forming an edge of the polygon graph.
/// </summary>
/// <param name="line">The line to add.</param>
public virtual void AddEdge(LineString line)
{
if (line.IsEmpty) return;
IList<Coordinate> linePts = CoordinateArrays.RemoveRepeatedPoints(line.Coordinates);
Coordinate startPt = linePts[0];
Coordinate endPt = linePts[linePts.Count - 1];
Node nStart = GetNode(startPt);
Node nEnd = GetNode(endPt);
DirectedEdge de0 = new PolygonizeDirectedEdge(nStart, nEnd, linePts[1], true);
DirectedEdge de1 = new PolygonizeDirectedEdge(nEnd, nStart, linePts[linePts.Count - 2], false);
Edge edge = new PolygonizeEdge(line);
edge.SetDirectedEdges(de0, de1);
Add(edge);
}
