/// <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);
}
public void DelaunayTriangulation2()
{
var m_delaunay = Delaunay.Create(m_arrowVertices);
Assert.IsTrue(Delaunay.IsValid(m_delaunay));
var triangles = (System.Collections.ICollection)m_delaunay.Triangles;
Assert.Contains(new Triangle(m_topVertex, m_rightVertex, m_botVertex), triangles);
Assert.Contains(new Triangle(m_topVertex, m_farRightVertex, m_rightVertex), triangles);
Assert.Contains(new Triangle(m_rightVertex, m_farRightVertex, m_botVertex), triangles);
}
public void DelaunayTriangulation1()
{
var m_delaunay = Delaunay.Create(m_diamondVertices);
Assert.IsTrue(Delaunay.IsValid(m_delaunay));
Assert.AreEqual(m_diamond.Area, m_delaunay.Area, MathUtil.EPS);
var triangles = (System.Collections.ICollection)m_delaunay.Triangles;
Assert.Contains(new Triangle(m_topVertex, m_rightVertex, m_leftVertex), triangles);
Assert.Contains(new Triangle(m_leftVertex, m_rightVertex, m_botVertex), triangles);
}
public void InValidTriangulationTest()
{
var m_delaunay = new Triangulation();
var t1 = new Triangle(m_topVertex, m_rightVertex, m_botVertex);
var t2 = new Triangle(m_topVertex, m_botVertex, m_leftVertex);
t1.E2.Twin = t2.E0;
t2.E0.Twin = t1.E2;
m_delaunay.AddTriangle(t1);
m_delaunay.AddTriangle(t2);
Assert.IsFalse(Delaunay.IsValid(m_delaunay));
}
public void DelaunayAddVertexTest()
{
var m_delaunay = Delaunay.Create();
Delaunay.AddVertex(m_delaunay, m_topVertex);
Delaunay.AddVertex(m_delaunay, m_botVertex);
Delaunay.AddVertex(m_delaunay, m_leftVertex);
Delaunay.AddVertex(m_delaunay, m_farRightVertex);
Delaunay.AddVertex(m_delaunay, m_rightVertex);
m_delaunay.RemoveInitialTriangle();
Assert.IsTrue(Delaunay.IsValid(m_delaunay));
// check for triangles
var triangles = (System.Collections.ICollection)m_delaunay.Triangles;
Assert.Contains(new Triangle(m_topVertex, m_rightVertex, m_leftVertex), triangles);
Assert.Contains(new Triangle(m_leftVertex, m_rightVertex, m_botVertex), triangles);
Assert.Contains(new Triangle(m_topVertex, m_farRightVertex, m_rightVertex), triangles);
Assert.Contains(new Triangle(m_rightVertex, m_farRightVertex, m_botVertex), triangles);
}
