/// <summary>
/// Inserts a new site into the Subdivision, connecting it to the vertices of
/// the containing triangle (or quadrilateral, if the split point falls on an
/// existing edge).
/// </summary>
/// <remarks>
/// <para>
/// This method does NOT maintain the Delaunay condition. If desired, this must
/// be checked and enforced by the caller.
/// </para>
/// <para>
/// This method does NOT check if the inserted vertex falls on an edge. This
/// must be checked by the caller, since this situation may cause erroneous
/// triangulation
/// </para>
/// </remarks>
/// <param name="v">the vertex to insert</param>
/// <returns>a new quad edge terminating in v</returns>
public QuadEdge InsertSite(Vertex v)
{
var e = Locate(v);
if ((v.Equals(e.Orig, _tolerance)) || (v.Equals(e.Dest, _tolerance)))
{
return(e); // point already in subdivision.
}
// Connect the new point to the vertices of the containing
// triangle (or quadrilateral, if the new point fell on an
// existing edge.)
var baseQE = MakeEdge(e.Orig, v);
QuadEdge.Splice(baseQE, e);
var startEdge = baseQE;
do
{
baseQE = Connect(e, baseQE.Sym);
e = baseQE.OPrev;
} while (e.LNext != startEdge);
return(startEdge);
}
private QuadEdge InitSubdiv()
{
// build initial subdivision from frame
var ea = MakeEdge(_frameVertex[0], _frameVertex[1]);
var eb = MakeEdge(_frameVertex[1], _frameVertex[2]);
QuadEdge.Splice(ea.Sym, eb);
var ec = MakeEdge(_frameVertex[2], _frameVertex[0]);
QuadEdge.Splice(eb.Sym, ec);
QuadEdge.Splice(ec.Sym, ea);
return(ea);
}
/// <summary>
/// Deletes a quadedge from the subdivision. Linked quadedges are updated to
/// reflect the deletion.
/// </summary>
/// <param name="e">the quadedge to delete</param>
public void Delete(QuadEdge e)
{
QuadEdge.Splice(e, e.OPrev);
QuadEdge.Splice(e.Sym, e.Sym.OPrev);
var eSym = e.Sym;
var eRot = e.Rot;
var eRotSym = e.Rot.Sym;
// this is inefficient on an ArrayList, but this method should be called infrequently
_quadEdges.Remove(e);
_quadEdges.Remove(eSym);
_quadEdges.Remove(eRot);
_quadEdges.Remove(eRotSym);
e.Delete();
eSym.Delete();
eRot.Delete();
eRotSym.Delete();
}
