Minor cleanup and updates to DCEL entities.

* Rename 'Boundary' property of HalfEdge class to 'Label'
* Add 'Label' property to Face class and initialize to generator label
* Update Voronoi tests.

Author: wo80

src/Triangle.Tests/Voronoi/BoundedVoronoiTest.cs

@@ -11,16 +11,23 @@ public class BoundedVoronoiTest
         [Test]
         public void TestBoundedVoronoi()
         {
-            var p = Helper.SplitRectangle(-1, 1, 1, -1, 3);
+            int boundaryLabel = 3;
+
+            var p = Helper.SplitRectangle(-1, 1, 1, -1, boundaryLabel);
+
+            Assert.That(p.Regions.Count, Is.EqualTo(2));
+
+            int regionLabel1 = p.Regions[0].Label;
+            int regionLabel2 = p.Regions[1].Label;
 
             var mesher = new GenericMesher();
             var mesh = (Mesh)mesher.Triangulate(p);
 
             var voronoi = new BoundedVoronoi(mesh);
 
             // The "split rectangle" polygon has two region pointer set.
-            Assert.That(voronoi.Vertices.Count(v => v.Label == 1), Is.EqualTo(2));
-            Assert.That(voronoi.Vertices.Count(v => v.Label == 2), Is.EqualTo(2));
+            Assert.That(voronoi.Vertices.Count(v => v.Label == regionLabel1), Is.EqualTo(2));
+            Assert.That(voronoi.Vertices.Count(v => v.Label == regionLabel2), Is.EqualTo(2));
 
             // The polygon has 6 boundary segments, so the Voronoi diagram
             // should have 6 infinite edges (which are projected onto the
@@ -32,6 +39,9 @@ public void TestBoundedVoronoi()
             // All Voronoi cells should have a generator vertex.
             Assert.That(voronoi.Faces.All(f => f.Generator is not null));
 
+            // All Voronoi cells should have the same label as the dual vertex.
+            Assert.That(voronoi.Faces.All(f => f.Label == boundaryLabel));
+
             // Check DCEL topology (all Voronoi cells should be closed).
             Assert.That(voronoi.IsConsistent());
         }

src/Triangle.Tests/Voronoi/StandardVoronoiTest.cs

@@ -11,16 +11,23 @@ public class StandardVoronoiTest
         [Test]
         public void TestStandardVoronoi()
         {
-            var p = Helper.SplitRectangle(-1, 1, 1, -1, 3);
+            int boundaryLabel = 3;
+
+            var p = Helper.SplitRectangle(-1, 1, 1, -1, boundaryLabel);
+
+            Assert.That(p.Regions.Count, Is.EqualTo(2));
+
+            int regionLabel1 = p.Regions[0].Label;
+            int regionLabel2 = p.Regions[1].Label;
 
             var mesher = new GenericMesher();
             var mesh = (Mesh)mesher.Triangulate(p);
 
             var voronoi = new StandardVoronoi(mesh);
 
             // The "split rectangle" polygon has two region pointer set.
-            Assert.That(voronoi.Vertices.Count(v => v.Label == 1), Is.EqualTo(2));
-            Assert.That(voronoi.Vertices.Count(v => v.Label == 2), Is.EqualTo(2));
+            Assert.That(voronoi.Vertices.Count(v => v.Label == regionLabel1), Is.EqualTo(2));
+            Assert.That(voronoi.Vertices.Count(v => v.Label == regionLabel2), Is.EqualTo(2));
 
             // The polygon has 6 boundary segments, so the Voronoi diagram
             // should have 6 infinite edges.
@@ -30,6 +37,9 @@ public void TestStandardVoronoi()
             // All Voronoi cells should have a generator vertex.
             Assert.That(voronoi.Faces.All(f => f.Generator is not null));
 
+            // All Voronoi cells should have the same label as the dual vertex.
+            Assert.That(voronoi.Faces.All(f => f.Label == boundaryLabel));
+
             // Check DCEL topology (account for unbounded Voronoi cells).
             Assert.That(voronoi.IsConsistent(false));
         }

src/Triangle/Topology/DCEL/DcelMesh.cs

@@ -48,34 +48,22 @@ protected DcelMesh(bool initialize)
         /// <summary>
         /// Gets the vertices of the Voronoi diagram.
         /// </summary>
-        public List<Vertex> Vertices
-        {
-            get { return vertices; }
-        }
+        public List<Vertex> Vertices => vertices;
 
         /// <summary>
         /// Gets the list of half-edges specify the Voronoi diagram topology.
         /// </summary>
-        public List<HalfEdge> HalfEdges
-        {
-            get { return edges; }
-        }
+        public List<HalfEdge> HalfEdges => edges;
 
         /// <summary>
         /// Gets the faces of the Voronoi diagram.
         /// </summary>
-        public List<Face> Faces
-        {
-            get { return faces; }
-        }
+        public List<Face> Faces => faces;
 
         /// <summary>
         /// Gets the collection of edges of the Voronoi diagram.
         /// </summary>
-        public IEnumerable<IEdge> Edges
-        {
-            get { return EnumerateEdges(); }
-        }
+        public IEnumerable<IEdge> Edges => EnumerateEdges();
 
         /// <summary>
         /// Check if the DCEL is consistent.
@@ -234,7 +222,7 @@ public void ResolveBoundaryEdges()
             var map = new Dictionary<int, HalfEdge>();
 
             // TODO: parallel?
-            foreach (var edge in this.edges)
+            foreach (var edge in edges)
             {
                 if (edge.twin == null)
                 {
@@ -252,7 +240,7 @@ public void ResolveBoundaryEdges()
                 edge.id = j++;
                 edge.next = map[edge.twin.origin.id];
 
-                this.edges.Add(edge);
+                edges.Add(edge);
             }
         }
 

src/Triangle/Topology/DCEL/Face.cs

@@ -10,7 +10,7 @@ namespace TriangleNet.Topology.DCEL
     using TriangleNet.Geometry;
 
     /// <summary>
-    /// A face of the DCEL datastructure.
+    /// A face of the DCEL data structure.
     /// </summary>
     public class Face
     {
@@ -30,7 +30,7 @@ static Face()
         #endregion
 
         internal int id;
-        internal int mark;
+        internal int label;
 
         // If the face is a Voronoi cell, this is the point that generates the cell.
         internal Point generator;
@@ -53,6 +53,18 @@ public int ID
             set { id = value; }
         }
 
+        /// <summary>
+        /// Gets or sets a general-purpose label.
+        /// </summary>
+        /// <remarks>
+        /// For Voronoi diagrams, this will be the same as the <see cref="Generator"/> label.
+        /// </remarks>
+        public int Label
+        {
+            get { return label; }
+            set { label = value; }
+        }
+
         /// <summary>
         /// Gets or sets a half-edge connected to the face.
         /// </summary>
@@ -95,6 +107,7 @@ public Face(Point generator, HalfEdge edge)
             if (generator != null)
             {
                 id = generator.ID;
+                label = generator.Label;
             }
         }
 

src/Triangle/Topology/DCEL/HalfEdge.cs

@@ -7,12 +7,12 @@
 namespace TriangleNet.Topology.DCEL
 {
     /// <summary>
-    /// A half-edge of the DCEL datastructure.
+    /// A half-edge of the DCEL data structure.
     /// </summary>
     public class HalfEdge
     {
         internal int id;
-        internal int mark;
+        internal int label;
 
         internal Vertex origin;
         internal Face face;
@@ -29,12 +29,15 @@ public int ID
         }
 
         /// <summary>
-        /// Gets or sets a boundary marker.
+        /// Gets or sets a general-purpose label.
         /// </summary>
-        public int Boundary
+        /// <remarks>
+        /// Can be used to identify boundary segments.
+        /// </remarks>
+        public int Label
         {
-            get { return mark; }
-            set { mark = value; }
+            get { return label; }
+            set { label = value; }
         }
 
         /// <summary>

src/Triangle/Voronoi/StandardVoronoi.cs

@@ -37,7 +37,7 @@ public StandardVoronoi(Mesh mesh, Rectangle box)
         /// Initializes a new instance of the <see cref="StandardVoronoi" /> class.
         /// </summary>
         /// <param name="mesh">The mesh.</param>
-        /// <param name="box">The bounding box used for clipping (not implemented.)</param>
+        /// <param name="box">The bounding box used for clipping (not implemented).</param>
         /// <param name="factory"></param>
         /// <param name="predicates"></param>
         public StandardVoronoi(Mesh mesh, Rectangle box, IVoronoiFactory factory, IPredicates predicates)