/// <summary>
/// Initializes a new instance of the <see cref="Face" /> class.
/// </summary>
/// <param name="generator">The generator of this face (for Voronoi diagram)</param>
/// <param name="edge">The half-edge connected to this face.</param>
public Face(Point generator, HalfEdge edge)
{
this.generator = generator;
this.edge = edge;
this.bounded = true;
if (generator != null)
{
this.id = generator.ID;
}
}
/// <summary>
/// Case 1: edge origin lies inside the domain.
/// </summary>
private void HandleCase1(HalfEdge edge, TVertex v1, TVertex v2)
{
//int mark = GetBoundaryMark(v1);
// The infinite vertex.
var v = (Point)edge.twin.origin;
// The half-edge is the bisector of v1 and v2, so the projection onto the
// boundary segment is actually its midpoint.
v.x = (v1.x + v2.x) / 2.0;
v.y = (v1.y + v2.y) / 2.0;
// Close the cell connected to edge.
var gen = factory.CreateVertex(v1.x, v1.y);
var h1 = factory.CreateHalfEdge(edge.twin.origin, edge.face);
var h2 = factory.CreateHalfEdge(gen, edge.face);
edge.next = h1;
h1.next = h2;
h2.next = edge.face.edge;
gen.leaving = h2;
// Let the face edge point to the edge leaving at generator.
edge.face.edge = h2;
base.edges.Add(h1);
base.edges.Add(h2);
int count = base.edges.Count;
h1.id = count;
h2.id = count + 1;
gen.id = offset++;
base.vertices.Add(gen);
}
public static DcelMesh ToDCEL(Mesh mesh)
{
var dcel = new DcelMesh();
var vertices = new HVertex[mesh.vertices.Count];
var faces = new Face[mesh.triangles.Count];
dcel.HalfEdges.Capacity = 2 * mesh.NumberOfEdges;
mesh.Renumber();
HVertex vertex;
foreach (var v in mesh.vertices.Values)
{
vertex = new HVertex(v.x, v.y);
vertex.id = v.id;
vertex.label = v.label;
vertices[v.id] = vertex;
}
// Maps a triangle to its 3 edges (used to set next pointers).
var map = new List<HalfEdge>[mesh.triangles.Count];
Face face;
foreach (var t in mesh.triangles)
{
face = new Face(null);
face.id = t.id;
faces[t.id] = face;
map[t.id] = new List<HalfEdge>(3);
}
Otri tri = default(Otri), neighbor = default(Otri);
TriangleNet.Geometry.Vertex org, dest;
int id, nid, count = mesh.triangles.Count;
HalfEdge edge, twin, next;
var edges = dcel.HalfEdges;
// Count half-edges (edge ids).
int k = 0;
// Maps a vertex to its leaving boundary edge.
var boundary = new Dictionary<int, HalfEdge>();
foreach (var t in mesh.triangles)
{
id = t.id;
tri.tri = t;
for (int i = 0; i < 3; i++)
{
tri.orient = i;
tri.Sym(ref neighbor);
nid = neighbor.tri.id;
if (id < nid || nid < 0)
{
face = faces[id];
// Get the endpoints of the current triangle edge.
org = tri.Org();
dest = tri.Dest();
// Create half-edges.
edge = new HalfEdge(vertices[org.id], face);
twin = new HalfEdge(vertices[dest.id], nid < 0 ? Face.Empty : faces[nid]);
map[id].Add(edge);
if (nid >= 0)
{
map[nid].Add(twin);
}
else
{
boundary.Add(dest.id, twin);
}
// Set leaving edges.
edge.origin.leaving = edge;
twin.origin.leaving = twin;
// Set twin edges.
edge.twin = twin;
twin.twin = edge;
edge.id = k++;
twin.id = k++;
edges.Add(edge);
edges.Add(twin);
}
}
}
// Set next pointers for each triangle face.
foreach (var t in map)
{
edge = t[0];
next = t[1];
if (edge.twin.origin.id == next.origin.id)
{
edge.next = next;
next.next = t[2];
t[2].next = edge;
}
else
{
edge.next = t[2];
next.next = edge;
t[2].next = next;
}
}
// Resolve boundary edges.
foreach (var e in boundary.Values)
{
e.next = boundary[e.twin.origin.id];
}
dcel.Vertices.AddRange(vertices);
dcel.Faces.AddRange(faces);
return dcel;
}
/// <summary>
/// Enumerates all half-edges of the face boundary.
/// </summary>
/// <returns></returns>
public IEnumerable<HalfEdge> EnumerateEdges()
{
var edge = this.Edge;
int first = edge.ID;
do
{
yield return edge;
edge = edge.Next;
} while (edge.ID != first);
}
/// <summary>
/// Case 2: edge origin lies outside the domain.
/// </summary>
private void HandleCase2(HalfEdge edge, TVertex v1, TVertex v2)
{
// The vertices of the infinite edge.
var p1 = (Point)edge.origin;
var p2 = (Point)edge.twin.origin;
// The two edges leaving p1, pointing into the mesh.
var e1 = edge.twin.next;
var e2 = e1.twin.next;
// Find the two intersections with boundary edge.
IntersectionHelper.IntersectSegments(v1, v2, e1.origin, e1.twin.origin, ref p2);
IntersectionHelper.IntersectSegments(v1, v2, e2.origin, e2.twin.origin, ref p1);
// The infinite edge will now lie on the boundary. Update pointers:
e1.twin.next = edge.twin;
edge.twin.next = e2;
edge.twin.face = e2.face;
e1.origin = edge.twin.origin;
edge.twin.twin = null;
edge.twin = null;
// Close the cell.
var gen = factory.CreateVertex(v1.x, v1.y);
var he = factory.CreateHalfEdge(gen, edge.face);
edge.next = he;
he.next = edge.face.edge;
// Let the face edge point to the edge leaving at generator.
edge.face.edge = he;
base.edges.Add(he);
he.id = base.edges.Count;
gen.id = offset++;
base.vertices.Add(gen);
}
/// <summary>
/// Initializes a new instance of the <see cref="Vertex" /> class.
/// </summary>
/// <param name="x">The x coordinate.</param>
/// <param name="y">The y coordinate.</param>
/// <param name="leaving">A half-edge leaving this vertex.</param>
public Vertex(double x, double y, HalfEdge leaving)
: base(x, y)
{
this.leaving = leaving;
}
/// <summary>
/// Initializes a new instance of the <see cref="Vertex" /> class.
/// </summary>
/// <param name="x">The x coordinate.</param>
/// <param name="y">The y coordinate.</param>
/// <param name="leaving">A half-edge leaving this vertex.</param>
public Vertex(float x, float y, HalfEdge leaving)
: base(x, y)
{
this.leaving = leaving;
}
/// <summary>
/// Initializes a new instance of the <see cref="Vertex" /> class.
/// </summary>
/// <param name="x">The x coordinate.</param>
/// <param name="y">The y coordinate.</param>
/// <param name="leaving">A half-edge leaving this vertex.</param>
public Vertex(double x, double y, HalfEdge leaving)
: base(x, y)
{
this.leaving = leaving;
}
