diff --git a/OpenNest.Engine/Fill/HorizontalRemnantComparer.cs b/OpenNest.Engine/Fill/HorizontalRemnantComparer.cs
new file mode 100644
index 0000000..0fba3ac
--- /dev/null
+++ b/OpenNest.Engine/Fill/HorizontalRemnantComparer.cs
@@ -0,0 +1,49 @@
+using System.Collections.Generic;
+using OpenNest.Geometry;
+using OpenNest.Math;
+
+namespace OpenNest.Engine.Fill
+{
+ ///
+ /// Ranks fill results to minimize Y-extent (preserve top-side horizontal remnant).
+ /// Tiebreak chain: count > smallest Y-extent > highest density.
+ ///
+ public class HorizontalRemnantComparer : IFillComparer
+ {
+ public bool IsBetter(List candidate, List current, Box workArea)
+ {
+ if (candidate == null || candidate.Count == 0)
+ return false;
+
+ if (current == null || current.Count == 0)
+ return true;
+
+ if (candidate.Count != current.Count)
+ return candidate.Count > current.Count;
+
+ var candExtent = YExtent(candidate);
+ var currExtent = YExtent(current);
+
+ if (!candExtent.IsEqualTo(currExtent))
+ return candExtent < currExtent;
+
+ return FillScore.Compute(candidate, workArea).Density
+ > FillScore.Compute(current, workArea).Density;
+ }
+
+ private static double YExtent(List parts)
+ {
+ var minY = double.MaxValue;
+ var maxY = double.MinValue;
+
+ foreach (var part in parts)
+ {
+ var bb = part.BoundingBox;
+ if (bb.Bottom < minY) minY = bb.Bottom;
+ if (bb.Top > maxY) maxY = bb.Top;
+ }
+
+ return maxY - minY;
+ }
+ }
+}
diff --git a/OpenNest.Engine/Fill/VerticalRemnantComparer.cs b/OpenNest.Engine/Fill/VerticalRemnantComparer.cs
new file mode 100644
index 0000000..a96f8ce
--- /dev/null
+++ b/OpenNest.Engine/Fill/VerticalRemnantComparer.cs
@@ -0,0 +1,49 @@
+using System.Collections.Generic;
+using OpenNest.Geometry;
+using OpenNest.Math;
+
+namespace OpenNest.Engine.Fill
+{
+ ///
+ /// Ranks fill results to minimize X-extent (preserve right-side vertical remnant).
+ /// Tiebreak chain: count > smallest X-extent > highest density.
+ ///
+ public class VerticalRemnantComparer : IFillComparer
+ {
+ public bool IsBetter(List candidate, List current, Box workArea)
+ {
+ if (candidate == null || candidate.Count == 0)
+ return false;
+
+ if (current == null || current.Count == 0)
+ return true;
+
+ if (candidate.Count != current.Count)
+ return candidate.Count > current.Count;
+
+ var candExtent = XExtent(candidate);
+ var currExtent = XExtent(current);
+
+ if (!candExtent.IsEqualTo(currExtent))
+ return candExtent < currExtent;
+
+ return FillScore.Compute(candidate, workArea).Density
+ > FillScore.Compute(current, workArea).Density;
+ }
+
+ private static double XExtent(List parts)
+ {
+ var minX = double.MaxValue;
+ var maxX = double.MinValue;
+
+ foreach (var part in parts)
+ {
+ var bb = part.BoundingBox;
+ if (bb.Left < minX) minX = bb.Left;
+ if (bb.Right > maxX) maxX = bb.Right;
+ }
+
+ return maxX - minX;
+ }
+ }
+}
diff --git a/OpenNest.Tests/FillComparerTests.cs b/OpenNest.Tests/FillComparerTests.cs
index da58eb8..b959020 100644
--- a/OpenNest.Tests/FillComparerTests.cs
+++ b/OpenNest.Tests/FillComparerTests.cs
@@ -63,3 +63,111 @@ public class DefaultFillComparerTests
Assert.True(comparer.IsBetter(candidate, current, workArea));
}
}
+
+public class VerticalRemnantComparerTests
+{
+ private readonly IFillComparer comparer = new VerticalRemnantComparer();
+ private readonly Box workArea = new(0, 0, 100, 100);
+
+ [Fact]
+ public void HigherCount_WinsRegardlessOfExtent()
+ {
+ var candidate = new List
+ {
+ TestHelpers.MakePartAt(0, 0, 10),
+ TestHelpers.MakePartAt(40, 0, 10),
+ TestHelpers.MakePartAt(80, 0, 10)
+ };
+ var current = new List
+ {
+ TestHelpers.MakePartAt(0, 0, 10),
+ TestHelpers.MakePartAt(12, 0, 10)
+ };
+ Assert.True(comparer.IsBetter(candidate, current, workArea));
+ }
+
+ [Fact]
+ public void SameCount_SmallerXExtent_Wins()
+ {
+ var candidate = new List
+ {
+ TestHelpers.MakePartAt(0, 0, 10),
+ TestHelpers.MakePartAt(12, 0, 10)
+ };
+ var current = new List
+ {
+ TestHelpers.MakePartAt(0, 0, 10),
+ TestHelpers.MakePartAt(50, 0, 10)
+ };
+ Assert.True(comparer.IsBetter(candidate, current, workArea));
+ }
+
+ [Fact]
+ public void SameCount_SameExtent_HigherDensityWins()
+ {
+ var candidate = new List
+ {
+ TestHelpers.MakePartAt(0, 0, 10),
+ TestHelpers.MakePartAt(40, 0, 10)
+ };
+ var current = new List
+ {
+ TestHelpers.MakePartAt(0, 0, 10),
+ TestHelpers.MakePartAt(40, 40, 10)
+ };
+ Assert.True(comparer.IsBetter(candidate, current, workArea));
+ }
+
+ [Fact]
+ public void NullCandidate_ReturnsFalse()
+ {
+ var current = new List { TestHelpers.MakePartAt(0, 0, 10) };
+ Assert.False(comparer.IsBetter(null, current, workArea));
+ }
+
+ [Fact]
+ public void NullCurrent_ReturnsTrue()
+ {
+ var candidate = new List { TestHelpers.MakePartAt(0, 0, 10) };
+ Assert.True(comparer.IsBetter(candidate, null, workArea));
+ }
+}
+
+public class HorizontalRemnantComparerTests
+{
+ private readonly IFillComparer comparer = new HorizontalRemnantComparer();
+ private readonly Box workArea = new(0, 0, 100, 100);
+
+ [Fact]
+ public void SameCount_SmallerYExtent_Wins()
+ {
+ var candidate = new List
+ {
+ TestHelpers.MakePartAt(0, 0, 10),
+ TestHelpers.MakePartAt(0, 12, 10)
+ };
+ var current = new List
+ {
+ TestHelpers.MakePartAt(0, 0, 10),
+ TestHelpers.MakePartAt(0, 50, 10)
+ };
+ Assert.True(comparer.IsBetter(candidate, current, workArea));
+ }
+
+ [Fact]
+ public void HigherCount_WinsRegardlessOfExtent()
+ {
+ var candidate = new List
+ {
+ TestHelpers.MakePartAt(0, 0, 10),
+ TestHelpers.MakePartAt(0, 40, 10),
+ TestHelpers.MakePartAt(0, 80, 10)
+ };
+ var current = new List
+ {
+ TestHelpers.MakePartAt(0, 0, 10),
+ TestHelpers.MakePartAt(0, 12, 10)
+ };
+ Assert.True(comparer.IsBetter(candidate, current, workArea));
+ }
+}