Tessellation to not reuse skipped sites again

Author: RudyTheDev

SharpVoronoiLib/Tessellation/Fortune/FortunesTessellation.cs

@@ -14,6 +14,10 @@ public List<VoronoiEdge> Run(List<VoronoiSite> sites, double minX, double minY,
 
         foreach (VoronoiSite site in sites)
         {
+            // If the site has already been marked as a duplicate before (such as prior to relaxing), skip it
+            if (site.SkippedAsDuplicate)
+                continue;
+            
             if (!siteCache.Add(site))
             {
                 site.MarkSkippedAsDuplicate();

UnitTests/LloydsAlgorithmTest.cs

@@ -39,4 +39,45 @@ public void TestRelax()
         Assert.That(sites, Has.Count.EqualTo(originalSites.Count));
         // todo: check movement
     }
+
+    [TestCase(1)]
+    [TestCase(2)] // this will tessellate in-between
+    public void TestRelaxingShouldNotUseDuplicateSites(int iterations)
+    {
+        // Arrange
+
+        List<VoronoiSite> originalSites =
+        [
+            new VoronoiSite(200, 100),
+            new VoronoiSite(100, 300),
+            new VoronoiSite(300, 400),
+            new VoronoiSite(400, 200),
+            new VoronoiSite(200, 100), // duplicate
+            new VoronoiSite(100, 300) // duplicate
+        ];
+
+        List<VoronoiSite> sites = new List<VoronoiSite>(originalSites); // copy so any changes to list don't affect the source list 
+
+        VoronoiPlane plane = new VoronoiPlane(0, 0, 600, 600);
+
+        plane.SetSites(sites);
+
+        plane.Tessellate();
+        
+        Assert.That(originalSites[0].SkippedAsDuplicate, Is.False);
+        Assert.That(originalSites[1].SkippedAsDuplicate, Is.False);
+        Assert.That(originalSites[2].SkippedAsDuplicate, Is.False);
+        Assert.That(originalSites[3].SkippedAsDuplicate, Is.False);
+        Assert.That(originalSites[4].SkippedAsDuplicate, Is.True);
+        Assert.That(originalSites[5].SkippedAsDuplicate, Is.True);
+
+        // Act
+
+        plane.Relax(iterations);
+
+        // Assert
+
+        Assert.That(originalSites[4].SkippedAsDuplicate, Is.True);
+        Assert.That(originalSites[5].SkippedAsDuplicate, Is.True);
+    }
 }