// PROTECTED METHODS
/// <summary>
/// Merge left and right most edges together to construct a cycling triangulation.
/// Needed for sphere for example after normal triangulation step.
/// </summary>
protected void CyclingMerge()
{
// @TODO Make sure CyclingMerge compute a valide triangulation
QuadEdge <TEdge> baseEdge = _mesh.RightMostEdge.Rnext;
QuadEdge <TEdge> lCand = baseEdge.Sym.Onext;
QuadEdge <TEdge> rCand = baseEdge.Oprev;
// Get edges CCW order from left extremum until reach right extremum
// to complete the sphere triangulation
// All edges must be stored first because pointer are updated
// during construction and will eventually leads to infinite loop ...
var toCheckEdge = rCand.LeftEdges(true).ToList();
foreach (QuadEdge <TEdge> rightEdge in toCheckEdge)
{
if (rightEdge.Destination != lCand.Destination)
{
// Connect rightEdge.Destination to baseEdge.Destination
// Construct a fan
baseEdge = QuadEdge <TEdge> .Connect(rightEdge, baseEdge.Sym);
}
else
{
break;
}
}
}
// PROTECTED METHOD
/// <summary>
/// Construct voronoi face based on Delaunay triangulation. Vertices at infinity
/// are define based on radius parameter. It should be large enough to avoid
/// some circumcenters (finite voronoi vertices) to be further on.
/// </summary>
/// <remarks>
/// Each face is yield just after their construction. Then it's neighborhood
/// is not guarantee to be constructed.
/// </remarks>
/// <param name="radius">Distance used to construct site that are at infinity.</param>
protected IEnumerable <Face <TEdge, TFace> > ExportFaces(Func <Vec3, Vec3, Vec3, Vec3> centerCalculator,
double radius)
{
// FIFO
var queue = new Queue <QuadEdge <TEdge> >();
// Start at the far left
QuadEdge <TEdge> first = _mesh.LeftMostEdge;
// @TODO Bounds
List <QuadEdge <TEdge> > bounds = new List <QuadEdge <TEdge> >();
// Visit all edge of the convex hull to compute dual vertices
// at infinity by looping in a CW order over edges with same left face.
foreach (QuadEdge <TEdge> hullEdge in first.LeftEdges(CCW:false))
{
// Construct a new face
// First infinite voronoi vertex
if (hullEdge.Rot.Destination == null)
{
hullEdge.Rot.Destination = ConstructAtInfinity(hullEdge.Sym,
radius,
centerCalculator);
}
// Add other vertices by looping over hullEdge origin in CW order (Oprev)
foreach (QuadEdge <TEdge> current in hullEdge.EdgesFrom(CCW:false))
{
if (current.Rot.Origin == null)
{
// Delaunay edge on the boundary
if (Geometry.LeftOf(current.Oprev.Destination, current))
{
current.Rot.Origin = ConstructAtInfinity(current,
radius,
centerCalculator);
}
else
{
current.Rot.Origin = centerCalculator(current.Origin,
current.Destination,
current.Oprev.Destination);
// Speed up computation of point coordinates
// All edges sharing the same origin should have same
// geometrical origin
foreach (QuadEdge <TEdge> otherDual in current.Rot.EdgesFrom())
{
otherDual.Origin = current.Rot.Origin;
}
}
}
if (current.Sym.Tag == _mesh.VisitedTagState)
{
queue.Enqueue(current.Sym);
bounds.Add(current.Sym);
}
current.Tag = !_mesh.VisitedTagState;
}
// After face construction over
yield return(new Face <TEdge, TFace>(hullEdge, true, true));
}
// Convex hull now closed --> Construct bounded voronoi faces
while (queue.Count > 0)
{
QuadEdge <TEdge> edge = queue.Dequeue();
if (edge.Tag == _mesh.VisitedTagState)
{
// Construct a new face
foreach (QuadEdge <TEdge> current in edge.EdgesFrom(CCW:false))
{
if (current.Rot.Origin == null)
{
current.Rot.Origin = centerCalculator(current.Origin,
current.Destination,
current.Oprev.Destination);
// Speed up computation of point coordinates
// All edges sharing the same origin have same
// geometrical origin
foreach (QuadEdge <TEdge> otherDual in current.Rot.EdgesFrom())
{
otherDual.Origin = current.Rot.Origin;
}
}
if (current.Sym.Tag == _mesh.VisitedTagState)
{
queue.Enqueue(current.Sym);
}
current.Tag = !_mesh.VisitedTagState;
}
// After face construction over
if (bounds.Contains(edge))
{
yield return(new Face <TEdge, TFace>(edge, true, false));
}
else
{
yield return(new Face <TEdge, TFace>(edge, false, false));
}
}
}
// Inverse flag to be able to traverse again at next call
_mesh.SwitchInternalFlag();
}