/// <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()
{
DCELHalfEdge he = this.Edge;
DCELHalfEdge prev = he.Previous();
DCELVertex first = he.Origin;
do
{
Vector3D v1 = new Vector3D(
prev.Origin.Coordinates.X - he.Origin.Coordinates.X,
prev.Origin.Coordinates.Y - he.Origin.Coordinates.Y,
prev.Origin.Coordinates.Z - he.Origin.Coordinates.Z);
Vector3D v2 = new Vector3D(
he.Next.Origin.Coordinates.X - he.Origin.Coordinates.X,
he.Next.Origin.Coordinates.Y - he.Origin.Coordinates.Y,
he.Next.Origin.Coordinates.Z - he.Origin.Coordinates.Z);
double dotProduct = (v1.X * v2.X + v1.Y * v2.Y + v1.Z * v2.Z);
double norm1 = Math.Sqrt(Math.Pow(v1.X, 2) + Math.Pow(v1.Y, 2) + Math.Pow(v1.Z, 2));
double norm2 = Math.Sqrt(Math.Pow(v2.X, 2) + Math.Pow(v2.Y, 2) + Math.Pow(v2.Z, 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 DCELHalfEdge(DCELVertex origin, DCELFace face, DCELHalfEdge twin, DCELHalfEdge next)
{
Origin = origin;
Face = face;
Twin = twin;
Next = next;
}
public bool AddVertex(DCELVertex vertex)
{
vertexList.Add(vertex);
vertexCount++;
return(true);
}
public bool RemoveVertex(DCELVertex vertex)
{
if (vertexList.Remove(vertex))
{
vertexCount--;
return(true);
}
return(false);
}
/// <summary>
/// Restituisce i lati della faccia.
/// </summary>
/// <returns>DCELHalfEdge collection.</returns>
public IEnumerable <DCELHalfEdge> Sides()
{
DCELHalfEdge he = this.Edge;
DCELVertex first = he.Origin;
do
{
yield return(he);
he = he.Next;
}while (he.Origin != first);
}
/// <summary>
/// Restituisce tutte le facce confinanti.
/// </summary>
/// <returns>DCELFace collection.</returns>
public IEnumerable <DCELFace> Neighbours()
{
DCELHalfEdge he = this.Edge;
DCELVertex first = he.Origin;
do
{
if (!he.Twin.Face.IsInfinite())
{
yield return(he.Twin.Face);
}
he = he.Next;
}while (he.Origin != first);
}
public bool TriangulateFace(DCELFace face)
{
//lista di appoggio
List <DCELHalfEdge> 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
DCELVertex 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 DCELFace(edges[i], face.Normal));
edges[i].Face = faceList[FaceCount - 1];
i++;
edges[i].Face = faceList[FaceCount - 1];
this.AddHalfEdge(new DCELHalfEdge(edges[i].Next.Origin, faceList[FaceCount - 1], null, edges[0]));
edges[i].Next = edgeList[HalfEdgeCount - 1];
}
else if (i == sides - 2)
{
this.AddFace(new DCELFace(null, face.Normal));
this.AddHalfEdge(new DCELHalfEdge(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 DCELFace(null, face.Normal));
this.AddHalfEdge(new DCELHalfEdge(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 DCELHalfEdge(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>
///
/// </summary>
/// <param name="mesh"></param>
/// <returns></returns>
public static MeshGeometry3D GetMeshGeometry(DCELMesh mesh)
{
MeshGeometry3D mesh3d = new MeshGeometry3D();
Hashtable vIndexes = new Hashtable();
int n = 0;
mesh.Triangulate();
foreach (var point3d in mesh.VertexList)
{
mesh3d.Positions.Add(point3d.Coordinates);
mesh3d.Normals.Add(point3d.Normal);
vIndexes.Add(point3d, n++);
}
foreach (var face in mesh.FaceList)
{
DCELHalfEdge he = face.Edge;
DCELVertex first = he.Origin;
do
{
mesh3d.TriangleIndices.Add((int)vIndexes[he.Origin]);
he = he.Next;
}while (he.Origin != first);
}
/*
* foreach (var face in mesh.FaceList)
* {
* DCELHalfEdge he = face.Edge;
* DCELVertex first = he.Origin;
*
* do
* {
* mesh3d.Positions.Add(he.Origin.Coordinates);
* mesh3d.Normals.Add(he.Origin.Normal);
* mesh3d.TriangleIndices.Add(n++);
* he = he.Next;
* }
* while (he.Origin != first);
* }
*/
return(mesh3d);
}
public bool Contains(DCELVertex vertex)
{
return(vertexList.Contains(vertex));
}
