/// <summary>
/// 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.
/// Precondition: edge intersections have been computed.
/// </summary>
/// <param name="geomGraph"></param>
/// <param name="argIndex"></param>
public void ComputeIntersectionNodes(GeometryGraph geomGraph, int argIndex)
{
for (IEnumerator edgeIt = geomGraph.GetEdgeEnumerator(); edgeIt.MoveNext(); )
{
Edge e = (Edge) edgeIt.Current;
Locations eLoc = e.Label.GetLocation(argIndex);
for (IEnumerator eiIt = e.EdgeIntersectionList.GetEnumerator(); eiIt.MoveNext(); )
{
EdgeIntersection ei = (EdgeIntersection) eiIt.Current;
RelateNode n = (RelateNode) nodes.AddNode(ei.Coordinate);
if (eLoc == Locations.Boundary)
n.SetLabelBoundary(argIndex);
else if (n.Label.IsNull(argIndex))
n.SetLabel(argIndex, Locations.Interior);
}
}
}
/// <summary>
///
/// </summary>
/// <param name="geomGraph"></param>
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();
IList eeList = eeBuilder.ComputeEdgeEnds(geomGraph.GetEdgeEnumerator());
InsertEdgeEnds(eeList);
}
/// <summary>
/// For all edges, check if there are any intersections which are NOT at an endpoint.
/// The Geometry is not simple if there are intersections not at endpoints.
/// </summary>
/// <param name="graph"></param>
private bool HasNonEndpointIntersection(GeometryGraph graph)
{
for (IEnumerator i = graph.GetEdgeEnumerator(); i.MoveNext(); )
{
Edge e = (Edge) i.Current;
int maxSegmentIndex = e.MaximumSegmentIndex;
for (IEnumerator eiIt = e.EdgeIntersectionList.GetEnumerator(); eiIt.MoveNext(); )
{
EdgeIntersection ei = (EdgeIntersection) eiIt.Current;
if (!ei.IsEndPoint(maxSegmentIndex))
return true;
}
}
return false;
}
/// <summary>
/// Check that there is no ring which self-intersects (except of course at its endpoints).
/// This is required by OGC topology rules (but not by other models
/// such as ESRI SDE, which allow inverted shells and exverted holes).
/// </summary>
/// <param name="graph"></param>
private void CheckNoSelfIntersectingRings(GeometryGraph graph)
{
for (IEnumerator i = graph.GetEdgeEnumerator(); i.MoveNext(); )
{
Edge e = (Edge) i.Current;
CheckNoSelfIntersectingRing(e.EdgeIntersectionList);
if (validErr != null) return;
}
}
/// <summary>
/// Test that no edge intersection is the
/// endpoint of a closed line. To check this we compute the
/// degree of each endpoint. The degree of endpoints of closed lines
/// must be exactly 2.
/// </summary>
/// <param name="graph"></param>
private bool HasClosedEndpointIntersection(GeometryGraph graph)
{
IDictionary endPoints = new SortedList();
for (IEnumerator i = graph.GetEdgeEnumerator(); i.MoveNext(); )
{
Edge e = (Edge) i.Current;
bool isClosed = e.IsClosed;
ICoordinate p0 = e.GetCoordinate(0);
AddEndpoint(endPoints, p0, isClosed);
ICoordinate p1 = e.GetCoordinate(e.NumPoints - 1);
AddEndpoint(endPoints, p1, isClosed);
}
for (IEnumerator i = endPoints.Values.GetEnumerator(); i.MoveNext(); )
{
EndpointInfo eiInfo = (EndpointInfo) i.Current;
if (eiInfo.IsClosed && eiInfo.Degree != 2)
return true;
}
return false;
}