Add examples project.

src/Triangle.Examples/Examples/Example9.cs

@@ -0,0 +1,84 @@
+
+namespace TriangleNet.Examples
+{
+    using System;
+    using System.Collections.Generic;
+    using System.Linq;
+    using TriangleNet.Geometry;
+
+    /// <summary>
+    /// Troubleshooting: finding degenerate boundary triangles.
+    /// </summary>
+    public class Example9
+    {
+        public static void Run()
+        {
+            var pts = new List<Vertex>
+            {
+                // The 4 corners of the square.
+                new Vertex(1.5, 1.0),
+                new Vertex(1.5, -1.0),
+                new Vertex(-1.5, -1.0),
+                new Vertex(-1.5, 1.0),
+
+                // The edge midpoints.
+                new Vertex(0.0, 1.0),
+                new Vertex(0.0, -1.0),
+                new Vertex(1.5, 0.0),
+                new Vertex(-1.5, 0.0)
+            };
+
+            var r = new Random(78403);
+
+            // The original rectangle.
+            var poly = Rotate(pts, 0);
+
+            for (int i = 0; i < 10; i++)
+            {
+                var mesh = poly.Triangulate();
+
+                var list = MeshValidator.GetDegenerateBoundaryTriangles(mesh);
+
+                if (list.Any())
+                {
+                    Console.WriteLine("Iteration {0}: found {1} degenerate triangle(s) of {2}.",
+                        i, list.Count(), mesh.Triangles.Count);
+
+                    foreach (var t in list)
+                    {
+                        Console.WriteLine("   [{0} {1} {2}]",
+                            t.GetVertexID(0),
+                            t.GetVertexID(1),
+                            t.GetVertexID(2));
+                    }
+                }
+
+                // Random rotation.
+                poly = Rotate(pts, Math.PI * r.NextDouble());
+            }
+        }
+
+        /// <summary>
+        /// Rotate given point set around the origin.
+        /// </summary>
+        private static IPolygon Rotate(List<Vertex> points, double radians)
+        {
+            var poly = new Polygon(points.Count);
+
+            int id = 0;
+
+            foreach (var p in points)
+            {
+                double x = p.X;
+                double y = p.Y;
+
+                double xr = Math.Cos(radians) * x - Math.Sin(radians) * y;
+                double yr = Math.Sin(radians) * x + Math.Cos(radians) * y;
+
+                poly.Points.Add(new Vertex(xr, yr) { ID = id++ });
+            }
+
+            return poly;
+        }
+    }
+}