private EdgeRing _shell; // if non-null, the ring is a hole and this EdgeRing is its containing shell
#endregion Fields
#region Constructors
/// <summary>
/// Initializes a new instance of the EdgeRing class.
/// </summary>
public EdgeRing( DirectedEdge start, GeometryFactory geometryFactory, CGAlgorithms cga )
{
_geometryFactory = geometryFactory;
_cga = cga;
ComputePoints(start);
ComputeRing();
}
public void ComputeDepths(DirectedEdge de)
{
int edgeIndex = FindIndex(de);
Label label = de.Label;
int startDepth = de.GetDepth( Position.Left );
// compute the depths from this edge up to the end of the edge array
int nextDepth = ComputeDepths( edgeIndex + 1, _edgeList.Count - 1, startDepth );
// compute the depths for the initial part of the array
int lastDepth = ComputeDepths( 0, edgeIndex, nextDepth );
//Trace.WriteLine( ToString() );
Trace.Assert( lastDepth == startDepth, "depth mismatch at " + de.Coordinate.ToString() );
}
public override DirectedEdge GetNext( DirectedEdge de )
{
return de.Next;
}
/// <summary>
/// Initializes a new instance of the MaximalEdgeRing class.
/// A MaximalEdgeRing is a ring of edges which may contain nodes of degree > 2.
/// A MaximalEdgeRing may represent two different spatial entities:
/// <ul>
/// <li>a single polygon possibly containing inversions (if the ring is oriented CW)
/// <li>a single hole possibly containing exversions (if the ring is oriented CCW)
/// </ul>
/// If the MaximalEdgeRing represents a polygon,
/// the interior of the polygon is strongly connected.
/// These are the form of rings used to define polygons under some spatial data models.
/// However, under the OGC SFS model, {@link MinimalEdgeRings} are required.
/// A MaximalEdgeRing can be converted to a list of MinimalEdgeRings using the
/// { BuildMinimalRings() } method.
/// </summary>
public MaximalEdgeRing( DirectedEdge start, GeometryFactory geometryFactory, CGAlgorithms cga ) : base( start, geometryFactory, cga )
{
}
/// <summary>
/// Collect all the points from the DirectedEdges of this ring into a contiguous list.
/// </summary>
/// <param name="start"></param>
protected void ComputePoints(DirectedEdge start)
{
_startDe = start;
DirectedEdge de = start;
bool isFirstEdge = true;
do
{
if ( de == null )
{
throw new InvalidOperationException("Found null Directed Edge.");
}
_edges.Add( de );
Label label = de.Label;
// Java used an assert here...
if ( !label.IsArea() )
{
throw new InvalidOperationException("Label IsArea() is false when true is expected.");
}
MergeLabel( label );
AddPoints( de.Edge, de.IsForward, isFirstEdge );
isFirstEdge = false;
SetEdgeRing( de, this );
de = GetNext( de ); // GetNext will be implemented in the inherited class...this class is abstract.
} while ( de != _startDe );
}
public abstract void SetEdgeRing( DirectedEdge de, EdgeRing er );
public abstract DirectedEdge GetNext( DirectedEdge de );
} // public void LinkAllDirectedEdges()
/// <summary>
/// Traverse the star edges, maintaing the current location in the result area
/// at this node (if any). If any L edges are found in the interior of the result,
/// mark them as covered.
/// </summary>
public void FindCoveredLineEdges()
{
//Trace.WriteLine("findCoveredLineEdges");
//Trace.WriteLine( ToString() );
// Since edges are stored in CCW order around the node,
// as we move around the ring we move from the right to the left side of the edge
// Find first DirectedEdge of result area (if any).
// The interior of the result is on the RHS of the edge,
// so the start location will be:
// - INTERIOR if the edge is outgoing
// - EXTERIOR if the edge is incoming
int startLoc = Location.Null;
foreach (DirectedEdge de in Edges())
{
DirectedEdge nextOut = de;
DirectedEdge nextIn = nextOut.Sym;
if (!nextOut.IsLineEdge)
{
if (nextOut.InResult)
{
startLoc = Location.Interior;
break;
}
if (nextIn.InResult)
{
startLoc = Location.Exterior;
break;
}
}
} // foreach ( object obj in edges )
// no A edges found, so can't determine if L edges are covered or not
if (startLoc == Location.Null)
{
return;
}
// move around ring, keeping track of the current location
// (Interior or Exterior) for the result area.
// If L edges are found, mark them as covered if they are in the interior
int currLoc = startLoc;
foreach (DirectedEdge de in Edges())
{
DirectedEdge nextOut = de;
DirectedEdge nextIn = nextOut.Sym;
if (nextOut.IsLineEdge)
{
nextOut.Edge.SetCovered = (currLoc == Location.Interior);
//Trace.WriteLine( nextOut.ToString() );
}
else
{ // edge is an Area edge
if (nextOut.InResult)
{
currLoc = Location.Exterior;
}
if (nextIn.InResult)
{
currLoc = Location.Interior;
}
}
} // foreach ( object obj in edges )
} // public void FindCoveredLineEdges()
} // private void CollectLines( int opCode )
/// <summary>
///
/// </summary>
/// <param name="de"></param>
/// <param name="opCode"></param>
/// <param name="edges"></param>
public void CollectLineEdge( DirectedEdge de, int opCode, ArrayList edges )
{
Label label = de.Label;
Edge e = de.Edge;
// include L edges which are in the result
if ( de.IsLineEdge )
{
if ( !de.Visited && OverlayOp.IsResultOfOp( label, opCode ) && !e.IsCovered )
{
//Trace.WriteLine("de: " + de.Label.ToString() );
//Trace.WriteLine("edge: " + e.Label.ToString() );
edges.Add( e );
de.SetVisitedEdge( true );
} // if ( !de.Visited && OverlayOp.IsResultOfOp( label, opCode ) && !e.IsCovered )
} // if ( de.IsLineEdge )
} // public void CollectLineEdge( DirectedEdge de, int opCode, ArrayList edges )
protected void VisitLinkedDirectedEdges(DirectedEdge start)
{
DirectedEdge startDe = start;
DirectedEdge de = start;
//Debug.println(de);
do
{
de.Visited=true;
de = de.Next;
//Debug.println(de);
} while (de != startDe);
}
abstract public void SetEdgeRing(DirectedEdge de, EdgeRing er);
} // public void ComputeRing()
abstract public DirectedEdge GetNext(DirectedEdge de);
/// <summary>
/// Insert a directed edge in the list.
/// </summary>
/// <param name="ee">The EdgeEnd to be inserted into the list. Must be of type DirectedEdge.</param>
public override void Insert(EdgeEnd ee)
{
DirectedEdge de = (DirectedEdge)ee;
InsertEdgeEnd(de, de);
}
public override void SetEdgeRing( DirectedEdge de, EdgeRing er )
{
de.EdgeRing = er;
}
} // public void CollectLineEdge( DirectedEdge de, int opCode, ArrayList edges )
/// <summary>
/// Collect edges from Area input which should be in the result by which have not been included
/// in a result area. This happens ONLY:
/// <ul>
/// <li>during an intersection when the boundaries of two areas touch in a line segment.
/// <li>OR as a result of a dimensional collapse.
/// </ul>
/// </summary>
/// <param name="de"></param>
/// <param name="opCode"></param>
/// <param name="edges"></param>
public void CollectBoundaryTouchEdge( DirectedEdge de, int opCode, ArrayList edges )
{
Label label = de.Label;
// this smells like a bit of a hack, but it seems to work...
if ( !de.IsLineEdge
&& !de.IsInteriorAreaEdge // added to handle dimensional collapses
&& !de.Edge.IsInResult
&& !de.Visited
&& OverlayOp.IsResultOfOp( label, opCode )
&& opCode == OverlayOp.Intersection )
{
edges.Add( de.Edge );
de.SetVisitedEdge( true );
}
} // public void CollectBoundaryTouchEdge( DirectedEdge de, int opCode, ArrayList edges )
/// <summary>
/// Add a set of edges to the graph. For each edge two DirectedEdges
/// will be created. DirectedEdges are NOT linked by this method.
/// </summary>
/// <param name="edgesToAdd"></param>
public void AddEdges( ArrayList edgesToAdd )
{
// create all the nodes for the edges
foreach( object objectEdge in edgesToAdd )
{
Edge e = (Edge) objectEdge;
_edges.Add( e );
DirectedEdge de1 = new DirectedEdge( e, true );
DirectedEdge de2 = new DirectedEdge( e, false );
de1.Sym = de2;
de2.Sym = de1;
Add( de1 );
Add( de2 );
} // foreach( object objectEdge in edgesToAdd )
}
} // private ArrayList GetResultAreaEdges()
/// <summary>
/// Traverse the star of DirectedEdges, linking the included edge together.
/// To link two dirEdges, the next pointer for an incoming dirEdge is set to the next outgoing edge.
///
/// DirEdges are only linked. If:
/// <ul>
/// <li>They belong to an area (i.e. they have sides)
/// <li>They are marked as being in the result.
/// </ul>
/// Edges are linked in CCW order (the order they are stored.) This means that rings have
/// their face on the Right ( in other words, the topological location of the face is given
/// by the RHS label of the DirectedEdge)
///
/// PRECONDITION: No pair of dirEdges are both marked as being in the result.
/// </summary>
public void LinkResultDirectedEdges()
{
// make sure edges are copied to resultAreaEdges list
GetResultAreaEdges();
// find first area edge (if any) to start linking at
DirectedEdge firstOut = null;
DirectedEdge incoming = null;
int state = ScanningForIncoming;
// link edges in CCW order
for (int i = 0; i < _resultAreaEdgeList.Count; i++)
{
DirectedEdge nextOut = (DirectedEdge)_resultAreaEdgeList[i];
DirectedEdge nextIn = nextOut.Sym;
// skip de's that we're not interested in
if (nextOut.Label.IsArea())
{
// record first outgoing edge, in order to link the last incoming edge
if (firstOut == null && nextOut.InResult)
{
firstOut = nextOut;
}
// assert: sym.isInResult() == false, since pairs of dirEdges should have been removed already
switch (state)
{
case ScanningForIncoming:
if (!nextIn.InResult)
{
continue;
}
incoming = nextIn;
state = LinkingToOutGoing;
break;
case LinkingToOutGoing:
if (!nextOut.InResult)
{
continue;
}
incoming.Next = nextOut;
state = ScanningForIncoming;
break;
} // switch ( state )
} // if ( nextOut.Label.IsArea() )
} // for (int i = 0; i < _resultAreaEdgeList.Count; i++)
//Trace.WriteLine( ToString() );
if (state == LinkingToOutGoing)
{
if (firstOut == null)
{
throw new TopologyException("No outgoing dirEdge found.");
}
if (!firstOut.InResult)
{
throw new TopologyException("Unable to link last incoming dirEdge.");
}
incoming.Next = firstOut;
}
} // public void LinkResultDirectedEdges()
