/// <summary>
/// Creates a Voronoi DCEL from a triangulation. Triangulation should be Delaunay
/// </summary>
/// <param name="m_Delaunay"></param>
/// <returns></returns>
public static DCEL Create(Triangulation m_Delaunay)
{
if (!Delaunay.IsValid(m_Delaunay))
{
throw new GeomException("Triangulation should be delaunay for the Voronoi diagram.");
}
var dcel = new DCEL();
// create vertices for each triangles circumcenter and store them in a dictionary
Dictionary <Triangle, DCELVertex> vertexMap = new Dictionary <Triangle, DCELVertex>();
foreach (var triangle in m_Delaunay.Triangles)
{
// degenerate triangle, just ignore
if (!triangle.Circumcenter.HasValue)
{
continue;
}
var vertex = new DCELVertex(triangle.Circumcenter.Value);
dcel.AddVertex(vertex);
vertexMap.Add(triangle, vertex);
}
// remember which edges where visited
// since each edge has a twin
var edgesVisited = new HashSet <TriangleEdge>();
foreach (var edge in m_Delaunay.Edges)
{
// either already visited twin edge or edge is outer triangle
if (edgesVisited.Contains(edge) || edge.IsOuter)
{
continue;
}
// add edge between the two adjacent triangles vertices
// vertices at circumcenter of triangle
if (edge.T != null && edge.Twin.T != null)
{
var v1 = vertexMap[edge.T];
var v2 = vertexMap[edge.Twin.T];
HalfEdge e1 = dcel.AddEdge(v1, v2);
e1.Twin.Face.owner = m_Delaunay.GetOwner(edge.Point1);
e1.Face.owner = m_Delaunay.GetOwner(edge.Point2);
edgesVisited.Add(edge);
edgesVisited.Add(edge.Twin);
}
}
return(dcel);
}