public DCELHalfEdge2D(DCELVertex2D origin, DCELFace2D face, DCELHalfEdge2D twin, DCELHalfEdge2D next)
{
Origin = origin;
Face = face;
Twin = twin;
Next = next;
}
/// <summary>
/// Verifica se la faccia è convessa. Un poligono semplice è strettamente convesso se ogni
/// angolo interno è strettamente inferiore a 180 gradi.
/// </summary>
/// <returns>True se la faccia è convessa, false altrimenti.</returns>
public bool IsConvex()
{
DCELHalfEdge2D he = this.Edge;
DCELHalfEdge2D prev = he.Previous();
DCELVertex2D first = he.Origin;
do
{
Vector v1 = new Vector(
prev.Origin.Coordinates.X - he.Origin.Coordinates.X,
prev.Origin.Coordinates.Y - he.Origin.Coordinates.Y);
Vector v2 = new Vector(
he.Next.Origin.Coordinates.X - he.Origin.Coordinates.X,
he.Next.Origin.Coordinates.Y - he.Origin.Coordinates.Y);
double dotProduct = (v1.X * v2.X + v1.Y * v2.Y);
double norm1 = Math.Sqrt(Math.Pow(v1.X, 2) + Math.Pow(v1.Y, 2));
double norm2 = Math.Sqrt(Math.Pow(v2.X, 2) + Math.Pow(v2.Y, 2));
double angle = (Math.Acos(dotProduct / (norm1 * norm2)) * 180) / Math.PI;
if (angle > 180)
{
return(false);
}
prev = he;
he = he.Next;
}while (he.Origin != first);
//returns true if every internal angle is less than or equal to 180 degrees
return(true);
}
public bool AddVertex(DCELVertex2D vertex)
{
vertexList.Add(vertex);
vertexCount++;
return(true);
}
public bool RemoveVertex(DCELVertex2D vertex)
{
if (vertexList.Remove(vertex))
{
vertexCount--;
return(true);
}
return(false);
}
/// <summary>
/// Restituisce i lati della faccia.
/// </summary>
/// <returns>DCELHalfEdge collection.</returns>
public IEnumerable <DCELHalfEdge2D> Sides()
{
DCELHalfEdge2D he = this.Edge;
DCELVertex2D first = he.Origin;
do
{
yield return(he);
he = he.Next;
}while (he.Origin != first);
}
public static IEnumerable <DCELHalfEdge2D> LeavingEdges(DCELMesh2D mesh, DCELVertex2D vertex, QueryExecutionMode executionMode)
{
var query = mesh.HalfEdgeList.AsEnumerable();
switch (executionMode)
{
case QueryExecutionMode.Default:
query = query.Where(x => x.Origin == vertex);
break;
case QueryExecutionMode.AsParallel:
query = query.AsParallel().Where(x => x.Origin == vertex);
break;
case QueryExecutionMode.ForEachLoop:
foreach (var leavingEdge in mesh.HalfEdgeList)
{
if (leavingEdge.Origin == vertex)
{
yield return(leavingEdge);
}
}
yield break;
case QueryExecutionMode.ForLoop:
for (int i = 0; i < mesh.HalfEdgeCount; i++)
{
if (mesh.HalfEdgeList[i].Origin == vertex)
{
yield return(mesh.HalfEdgeList[i]);
}
}
yield break;
case QueryExecutionMode.ForWithAssignment:
int n = mesh.HalfEdgeCount;
for (int i = 0; i < n; i++)
{
if (mesh.HalfEdgeList[i].Origin == vertex)
{
yield return(mesh.HalfEdgeList[i]);
}
}
yield break;
}
foreach (var leavingEdge in query)
{
yield return(leavingEdge);
}
}
public bool TriangulateFace(DCELFace2D face)
{
//lista di appoggio
List <DCELHalfEdge2D> edges = face.Sides().ToList();
//sides è il numero di lati della faccia
int sides = edges.Count;
//first è il vertice a partire dal quale viene suddiviso il poligono
DCELVertex2D first = edges[0].Origin;
//se la faccia non esiste o se esiste ma ha meno di 4 lati o non è convessa restituisco false
//if (sides <= 3 || !this.Contains(face) || !face.IsConvex())
// return false;
for (int i = 0; i < sides; i++)
{
if (i == 0)
{
this.AddFace(new DCELFace2D(edges[i]));
edges[i].Face = faceList[FaceCount - 1];
i++;
edges[i].Face = faceList[FaceCount - 1];
this.AddHalfEdge(new DCELHalfEdge2D(edges[i].Next.Origin, faceList[FaceCount - 1], null, edges[0]));
edges[i].Next = edgeList[HalfEdgeCount - 1];
}
else if (i == sides - 2)
{
this.AddFace(new DCELFace2D(null));
this.AddHalfEdge(new DCELHalfEdge2D(first, faceList[FaceCount - 1], edgeList[HalfEdgeCount - 1], edges[i]));
edges[i].Face = faceList[FaceCount - 1];
i++;
edges[i].Face = faceList[FaceCount - 1];
edgeList[HalfEdgeCount - 2].Twin = edgeList[HalfEdgeCount - 1];
faceList[FaceCount - 1].Edge = edgeList[HalfEdgeCount - 1];
edges[i].Next = edgeList[HalfEdgeCount - 1];
}
else
{
this.AddFace(new DCELFace2D(null));
this.AddHalfEdge(new DCELHalfEdge2D(first, faceList[FaceCount - 1], edgeList[HalfEdgeCount - 1], edges[i]));
faceList[FaceCount - 1].Edge = edgeList[HalfEdgeCount - 1];
edges[i].Face = faceList[FaceCount - 1];
edgeList[HalfEdgeCount - 2].Twin = edgeList[HalfEdgeCount - 1];
this.AddHalfEdge(new DCELHalfEdge2D(edges[i].Next.Origin, faceList[faceCount - 1], null, edgeList[HalfEdgeCount - 1]));
edges[i].Next = edgeList[HalfEdgeCount - 1];
}
}
//ora è possibile rimuovere la faccia dalla lista
return(RemoveFace(face));
}
/// <summary>
/// Restituisce tutte le facce confinanti.
/// </summary>
/// <returns>DCELFace collection.</returns>
public IEnumerable <DCELFace2D> Neighbours()
{
DCELHalfEdge2D he = this.Edge;
DCELVertex2D first = he.Origin;
do
{
if (he.Twin != null)
{
if (!he.Twin.Face.IsInfinite())
{
yield return(he.Twin.Face);
}
}
he = he.Next;
}while (he.Origin != first);
}
public bool Contains(DCELVertex2D vertex)
{
return(vertexList.Contains(vertex));
}
