Add RandomSource to Configuration class (closes #19).

src/Triangle.Examples/Examples/ExamplePar.cs

@@ -48,7 +48,8 @@ namespace TriangleNet.Examples
                     var config = new Configuration()
                     {
                         Predicates = () => predicates,
-                        TrianglePool = () => pool.Restart()
+                        TrianglePool = () => pool.Restart(),
+                        RandomSource = () => Random.Shared
                     };
 
                     var triangulator = new Dwyer();
@@ -118,7 +119,8 @@ namespace TriangleNet.Examples
                     var config = new Configuration()
                     {
                         Predicates = () => predicates,
-                        TrianglePool = () => pool.Restart()
+                        TrianglePool = () => pool.Restart(),
+                        RandomSource = () => Random.Shared
                     };
 
                     var mesher = new GenericMesher(config);

src/Triangle/Configuration.cs

@@ -34,11 +34,12 @@ namespace TriangleNet
         /// Initializes a new instance of the <see cref="Configuration" /> class.
         /// </summary>
         /// <param name="predicates">Factory method for <see cref="IPredicates" />.</param>
-        /// <param name="trianglePool">Factory method for <see cref="TrianglePool" />.</param>
+        /// <param name="trianglePool">Factory method for <see cref="TriangleNet.TrianglePool" />.</param>
         public Configuration(Func<IPredicates> predicates, Func<TrianglePool> trianglePool)
         {
             Predicates = predicates;
             TrianglePool = trianglePool;
+            RandomSource = () => new Random();
         }
 
         /// <summary>
@@ -47,8 +48,13 @@ namespace TriangleNet
         public Func<IPredicates> Predicates { get; set; }
 
         /// <summary>
-        /// Gets or sets the factory method for the <see cref="TrianglePool"/>.
+        /// Gets or sets the factory method for the <see cref="TriangleNet.TrianglePool"/>.
         /// </summary>
         public Func<TrianglePool> TrianglePool { get; set; }
+
+        /// <summary>
+        /// Gets or sets the factory method for a <see cref="Random"/> source.
+        /// </summary>
+        public Func<Random> RandomSource { get; set; }
     }
 }

src/Triangle/Mesh.cs

@@ -214,7 +214,7 @@ namespace TriangleNet
 
             predicates = config.Predicates();
 
-            locator = new TriangleLocator(this, predicates);
+            locator = new TriangleLocator(this, predicates, config.RandomSource());
 
             TransferNodes(points);
         }

src/Triangle/TriangleLocator.cs

@@ -7,6 +7,7 @@
 
 namespace TriangleNet
 {
+    using System;
     using TriangleNet.Geometry;
     using TriangleNet.Topology;
 
@@ -24,35 +25,26 @@ namespace TriangleNet
     /// </remarks>
     public class TriangleLocator
     {
-        TriangleSampler sampler;
-        Mesh mesh;
-
-        IPredicates predicates;
+        private readonly TriangleSampler sampler;
+        private readonly Mesh mesh;
+        private readonly IPredicates predicates;
 
         // Pointer to a recently visited triangle. Improves point location if
         // proximate vertices are inserted sequentially.
         internal Otri recenttri;
         
-        /// <summary>
-        /// Initializes a new instance of the <see cref="TriangleLocator" /> class.
-        /// </summary>
-        /// <param name="mesh">The mesh.</param>
-        public TriangleLocator(Mesh mesh)
-            : this(mesh, RobustPredicates.Default)
-        {
-        }
-
         /// <summary>
         /// Initializes a new instance of the <see cref="TriangleLocator" /> class.
         /// </summary>
         /// <param name="mesh">The mesh.</param>
         /// <param name="predicates">The predicates.</param>
-        public TriangleLocator(Mesh mesh, IPredicates predicates)
+        /// <param name="random">The random source used in <see cref="TriangleSampler" />.</param>
+        public TriangleLocator(Mesh mesh, IPredicates predicates, Random random)
         {
             this.mesh = mesh;
             this.predicates = predicates;
 
-            sampler = new TriangleSampler(mesh);
+            sampler = new TriangleSampler(mesh, random);
         }
 
         /// <summary>

src/Triangle/TriangleSampler.cs

@@ -16,13 +16,11 @@ namespace TriangleNet
     /// </summary>
     class TriangleSampler : IEnumerable<Triangle>
     {
-        private const int RANDOM_SEED = 110503;
-
         // Empirically chosen factor.
         private const int samplefactor = 11;
 
-        private Random random;
-        private Mesh mesh;
+        private readonly Random random;
+        private readonly Mesh mesh;
 
         // Number of random samples for point location (at least 1).
         private int samples = 1;
@@ -30,11 +28,6 @@ namespace TriangleNet
         // Number of triangles in mesh.
         private int triangleCount = 0;
 
-        public TriangleSampler(Mesh mesh)
-            : this(mesh, new Random(RANDOM_SEED))
-        {
-        }
-
         public TriangleSampler(Mesh mesh, Random random)
         {
             this.mesh = mesh;
@@ -46,8 +39,8 @@ namespace TriangleNet
         /// </summary>
         public void Reset()
         {
-            this.samples = 1;
-            this.triangleCount = 0;
+            samples = 1;
+            triangleCount = 0;
         }
 
         /// <summary>