Added Convex Hull (chatgpt) - added DelayAsync to ChatGpt generated content

DelauneyTriangulation/ViewModels/MainWindowViewModel.cs

@@ -227,12 +227,14 @@ public partial class MainWindowViewModel : ViewModelBase
         return $"{Q(ax)},{Q(ay)}|{Q(bx)},{Q(by)}";
     }
 
-    void DrawCircles(IEnumerable<Geometries.Triangle> triangles, Geometries.Point superA, Geometries.Point superB,
+    async Task DrawCircles(CancellationToken ct, IEnumerable<Geometries.Triangle> triangles, Geometries.Point superA, Geometries.Point superB,
         Geometries.Point superC)
     {
         Circles.Clear();
         foreach (var t in triangles)
         {
+            ct.ThrowIfCancellationRequested();
+
             if (UsesVertex(t, superA) || UsesVertex(t, superB) || UsesVertex(t, superC)) continue;
             try
             {
@@ -242,7 +244,10 @@ public partial class MainWindowViewModel : ViewModelBase
 
                 var cc = new Geometries.Circle(a, b, c);
                 if (double.IsFinite(cc.X) && double.IsFinite(cc.Y) && double.IsFinite(cc.R) && cc.R > 0)
+                {
                     Circles.Add(cc);
+                    await DelayAsync(ct);
+                }
             }
             catch (ArgumentException)
             {
@@ -250,13 +255,15 @@ public partial class MainWindowViewModel : ViewModelBase
         }
     }
 
-    void BuildVoronoi(Geometries.Point sa, Geometries.Point sb, Geometries.Point sc)
+    async Task BuildVoronoi(CancellationToken ct, Geometries.Point sa, Geometries.Point sb, Geometries.Point sc)
     {
         VoronoiDiagram.Clear();
 
         var center = new Dictionary<Geometries.Triangle, (double x, double y)>();
         foreach (var t in Triangles)
         {
+            ct.ThrowIfCancellationRequested();
+
             if (UsesVertex(t, sa) || UsesVertex(t, sb) || UsesVertex(t, sc)) continue;
             try
             {
@@ -274,6 +281,8 @@ public partial class MainWindowViewModel : ViewModelBase
         var map = new Dictionary<string, (Geometries.Edge edge, List<Geometries.Triangle> tris)>();
         foreach (var t in Triangles)
         {
+            ct.ThrowIfCancellationRequested();
+
             if (UsesVertex(t, sa) || UsesVertex(t, sb) || UsesVertex(t, sc)) continue;
             foreach (var e in ExtractTriangleEdges(t))
             {
@@ -287,11 +296,16 @@ public partial class MainWindowViewModel : ViewModelBase
         var far = 10 * Math.Max(Width, Height);
         foreach (var kv in map.Values)
         {
+            ct.ThrowIfCancellationRequested();
+
             var e = kv.edge;
             var tris = kv.tris;
 
             if (tris.Count == 2 && center.TryGetValue(tris[0], out var c0) && center.TryGetValue(tris[1], out var c1))
+            {
                 VoronoiDiagram.Add(new Geometries.Edge(c0.x, c0.y, c1.x, c1.y));
+                await DelayAsync(ct);
+            }
 
             else if (tris.Count == 1 && center.TryGetValue(tris[0], out var c))
             {
@@ -320,10 +334,57 @@ public partial class MainWindowViewModel : ViewModelBase
                 }
 
                 VoronoiDiagram.Add(new Geometries.Edge(c.x, c.y, c.x + nx * far, c.y + ny * far));
+                await DelayAsync(ct);
             }
         }
     }
 
+    static double Cross(Geometries.Point o, Geometries.Point a, Geometries.Point b) =>
+        (a.X - o.X) * (b.Y - o.Y) - (a.Y - o.Y) * (b.X - o.X);
+
+    List<Geometries.Point> ComputeConvexHull(IList<Geometries.Point> pts)
+    {
+        if (pts.Count <= 1) return pts.ToList();
+
+        var p = pts.OrderBy(x => x.X).ThenBy(x => x.Y).ToList();
+
+        var lower = new List<Geometries.Point>();
+        foreach (var pt in p)
+        {
+            while (lower.Count >= 2 && Cross(lower[^2], lower[^1], pt) <= 0) lower.RemoveAt(lower.Count - 1);
+            lower.Add(pt);
+        }
+
+        var upper = new List<Geometries.Point>();
+        for (int i = p.Count - 1; i >= 0; i--)
+        {
+            var pt = p[i];
+            while (upper.Count >= 2 && Cross(upper[^2], upper[^1], pt) <= 0) upper.RemoveAt(upper.Count - 1);
+            upper.Add(pt);
+        }
+
+        lower.RemoveAt(lower.Count - 1);
+        upper.RemoveAt(upper.Count - 1);
+        return lower.Concat(upper).ToList();
+    }
+
+    async Task DrawConvexHull(CancellationToken ct)
+    {
+        Edges.Clear();
+        var hull = ComputeConvexHull(Points);
+        if (hull.Count < 2) return;
+
+        for (int i = 0; i < hull.Count; i++)
+        {
+            ct.ThrowIfCancellationRequested();
+
+            var a = hull[i];
+            var b = hull[(i + 1) % hull.Count];
+            Edges.Add(new Geometries.Edge(a.X, a.Y, b.X, b.Y));
+            await DelayAsync(ct);
+        }
+    }
+
     async Task BowyerWatson(CancellationToken ct)
     {
         Triangles.Clear();
@@ -351,8 +412,7 @@ public partial class MainWindowViewModel : ViewModelBase
                 }
             }
 
-            DrawCircles(bad, sa, sb, sc);
+            await DrawCircles(ct, bad, sa, sb, sc);
-            await DelayAsync(ct);
 
             var edgeCount = new Dictionary<string, Geometries.Edge>();
             var counter = new Dictionary<string, int>();
@@ -391,11 +451,9 @@ public partial class MainWindowViewModel : ViewModelBase
         var toRemove = Triangles.Where(t => UsesVertex(t, sa) || UsesVertex(t, sb) || UsesVertex(t, sc)).ToList();
         foreach (var t in toRemove) Triangles.Remove(t);
 
-        DrawCircles(Triangles, sa, sb, sc);
+        await DrawCircles(ct, Triangles, sa, sb, sc);
-        await DelayAsync(ct);
+        await BuildVoronoi(ct, sa, sb, sc);
-
+        await DrawConvexHull(ct);
-        BuildVoronoi(sa, sb, sc);
-        await DelayAsync(ct);
     }
 
     async Task DelaunayTriangulateAsync(CancellationToken ct)