/// <summary>
/// Initializes this Edge's two DirectedEdges, and for each DirectedEdge: sets the
/// Edge, sets the symmetric DirectedEdge, and adds this Edge to its from-Node.
/// </summary>
/// <param name="de0"></param>
/// <param name="de1"></param>
public void SetDirectedEdges(DirectedEdge de0, DirectedEdge de1)
{
dirEdge = new DirectedEdge[] { de0, de1, };
de0.Edge = this;
de1.Edge = this;
de0.Sym = de1;
de1.Sym = de0;
de0.FromNode.AddOutEdge(de0);
de1.FromNode.AddOutEdge(de1);
}
/// <summary>
///
/// </summary>
/// <param name="de"></param>
/// <param name="pos"></param>
/// <param name="list"></param>
/// <param name="expectedClosed"></param>
/// <returns></returns>
private LinkedListNode<DirectedEdge> AddReverseSubpath(DirectedEdge de, LinkedListNode<DirectedEdge> pos,
LinkedList<DirectedEdge> list, bool expectedClosed)
{
// trace an unvisited path *backwards* from this de
Node endNode = de.ToNode;
Node fromNode = null;
while (true)
{
if (pos == null)
pos = list.AddLast(de.Sym);
else pos = list.AddAfter(pos, de.Sym);
de.Edge.Visited = true;
fromNode = de.FromNode;
DirectedEdge unvisitedOutDE = FindUnvisitedBestOrientedDE(fromNode);
// this must terminate, since we are continually marking edges as visited
if (unvisitedOutDE == null)
break;
de = unvisitedOutDE.Sym;
}
if (expectedClosed)
{
// the path should end at the toNode of this de, otherwise we have an error
Assert.IsTrue(fromNode == endNode, "path not contiguous");
}
return pos;
}
/// <summary>
/// Drops a member of this DirectedEdgeStar.
/// </summary>
/// <param name="de"></param>
public void Remove(DirectedEdge de)
{
outEdges.Remove(de);
}
/// <summary>
/// Adds a new member to this DirectedEdgeStar.
/// </summary>
/// <param name="de"></param>
public void Add(DirectedEdge de)
{
outEdges.Add(de);
sorted = false;
}
/// <summary>
/// Returns the DirectedEdge on the left-hand side of the given DirectedEdge (which
/// must be a member of this DirectedEdgeStar).
/// </summary>
/// <param name="dirEdge"></param>
/// <returns></returns>
public DirectedEdge GetNextEdge(DirectedEdge dirEdge)
{
int i = GetIndex(dirEdge);
return (DirectedEdge)outEdges[GetIndex(i + 1)];
}
/// <summary>
/// Returns the zero-based index of the given DirectedEdge, after sorting in ascending order
/// by angle with the positive x-axis.
/// </summary>
/// <param name="dirEdge"></param>
/// <returns></returns>
public int GetIndex(DirectedEdge dirEdge)
{
SortEdges();
for (int i = 0; i < outEdges.Count; i++)
{
DirectedEdge de = (DirectedEdge)outEdges[i];
if (de == dirEdge)
return i;
}
return -1;
}
/// <summary>
/// Adds an outgoing DirectedEdge to this Node.
/// </summary>
/// <param name="de"></param>
public void AddOutEdge(DirectedEdge de)
{
deStar.Add(de);
}
/// <summary>
/// Removes this directed edge from its containing graph.
/// </summary>
internal void Remove()
{
this.sym = null;
this.parentEdge = null;
}
/// <summary>
/// Drops a member of this DirectedEdgeStar.
/// </summary>
/// <param name="de"></param>
public void Remove(DirectedEdge de)
{
outEdges.Remove(de);
}
/// <summary>
/// Adds a new member to this DirectedEdgeStar.
/// </summary>
/// <param name="de"></param>
public void Add(DirectedEdge de)
{
outEdges.Add(de);
sorted = false;
}
/// <summary>
/// Returns the DirectedEdge on the left-hand side of the given DirectedEdge (which
/// must be a member of this DirectedEdgeStar).
/// </summary>
/// <param name="dirEdge"></param>
/// <returns></returns>
public DirectedEdge GetNextEdge(DirectedEdge dirEdge)
{
int i = GetIndex(dirEdge);
return((DirectedEdge)outEdges[GetIndex(i + 1)]);
}
/// <summary>
/// Constructs an Edge initialized with the given DirectedEdges, and for each
/// DirectedEdge: sets the Edge, sets the symmetric DirectedEdge, and adds
/// this Edge to its from-Node.
/// </summary>
/// <param name="de0"></param>
/// <param name="de1"></param>
public Edge(DirectedEdge de0, DirectedEdge de1)
{
SetDirectedEdges(de0, de1);
}
/// <summary>
/// Adds the Edge to this PlanarGraph; only subclasses can add DirectedEdges,
/// to ensure the edges added are of the right class.
/// </summary>
/// <param name="dirEdge"></param>
protected void Add(DirectedEdge dirEdge)
{
dirEdges.Add(dirEdge);
}
/// <summary>
/// Adds an outgoing DirectedEdge to this Node.
/// </summary>
/// <param name="de"></param>
public void AddOutEdge(DirectedEdge de)
{
deStar.Add(de);
}
/// <summary>
/// Removes DirectedEdge from its from-Node and from this PlanarGraph. Note:
/// This method does not remove the Nodes associated with the DirectedEdge,
/// even if the removal of the DirectedEdge reduces the degree of a Node to
/// zero.
/// </summary>
/// <param name="de"></param>
public void Remove(DirectedEdge de)
{
DirectedEdge sym = de.Sym;
if (sym != null)
sym.Sym = null;
de.FromNode.OutEdges.Remove(de);
de.Remove();
dirEdges.Remove(de);
}
/// <summary>
/// Adds a DirectedEdge which is known to form part of this ring.
/// </summary>
/// <param name="de">The DirectedEdge to add.</param>
public void Add(DirectedEdge de)
{
deList.Add(de);
}
/// <summary>
/// Adds the Edge to this PlanarGraph; only subclasses can add DirectedEdges,
/// to ensure the edges added are of the right class.
/// </summary>
/// <param name="dirEdge"></param>
protected void Add(DirectedEdge dirEdge)
{
dirEdges.Add(dirEdge);
}
/// <summary>
/// Returns 1 if this DirectedEdge has a greater angle with the
/// positive x-axis than b", 0 if the DirectedEdges are collinear, and -1 otherwise.
/// Using the obvious algorithm of simply computing the angle is not robust,
/// since the angle calculation is susceptible to roundoff. A robust algorithm
/// is:
/// first compare the quadrants. If the quadrants are different, it it
/// trivial to determine which vector is "greater".
/// if the vectors lie in the same quadrant, the robust
/// <c>RobustCGAlgorithms.ComputeOrientation(Coordinate, Coordinate, Coordinate)</c>
/// function can be used to decide the relative orientation of the vectors.
/// </summary>
/// <param name="obj"></param>
/// <returns></returns>
public int CompareTo(Object obj)
{
DirectedEdge de = (DirectedEdge)obj;
return(CompareDirection(de));
}
