fix: correct Width/Length axis mapping and add spiral center-fill

Box constructor and derived properties (Right, Top, Center, Translate, Offset)
had Width and Length swapped — Length is X axis, Width is Y axis. Corrected
across Core geometry, plate bounding box, rectangle packing, fill algorithms,
tests, and UI renderers.

Added FillSpiral with center remnant detection and recursive FillBest on
the gap between the 4 spiral quadrants. RectFill.FillBest now compares
spiral+center vs full best-fit fairly. BestCombination returns a
CombinationResult record instead of out params.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

OpenNest.Core/CutOff.cs

@@ -50,13 +50,13 @@ namespace OpenNest
             {
                 cutPosition = Position.X;
                 lineStart = StartLimit ?? bounds.Y;
-                lineEnd = EndLimit ?? (bounds.Y + bounds.Length + settings.Overtravel);
+                lineEnd = EndLimit ?? (bounds.Y + bounds.Width + settings.Overtravel);
             }
             else
             {
                 cutPosition = Position.Y;
                 lineStart = StartLimit ?? bounds.X;
-                lineEnd = EndLimit ?? (bounds.X + bounds.Width + settings.Overtravel);
+                lineEnd = EndLimit ?? (bounds.X + bounds.Length + settings.Overtravel);
             }
 
             var exclusions = new List<(double Start, double End)>();
@@ -176,13 +176,13 @@ namespace OpenNest
 
         private (double Min, double Max) AxisBounds(Box bb, double clearance) =>
             Axis == CutOffAxis.Vertical
-                ? (bb.X - clearance, bb.X + bb.Width + clearance)
+                ? (bb.X - clearance, bb.X + bb.Length + clearance)
-                : (bb.Y - clearance, bb.Y + bb.Length + clearance);
+                : (bb.Y - clearance, bb.Y + bb.Width + clearance);
 
         private (double Start, double End) CrossAxisBounds(Box bb, double clearance) =>
             Axis == CutOffAxis.Vertical
-                ? (bb.Y - clearance, bb.Y + bb.Length + clearance)
+                ? (bb.Y - clearance, bb.Y + bb.Width + clearance)
-                : (bb.X - clearance, bb.X + bb.Width + clearance);
+                : (bb.X - clearance, bb.X + bb.Length + clearance);
 
         private Program BuildProgram(List<(double Start, double End)> segments, CutOffSettings settings)
         {

OpenNest.Core/Geometry/Arc.cs

@@ -420,8 +420,8 @@ namespace OpenNest.Geometry
 
             boundingBox.X = minX;
             boundingBox.Y = minY;
-            boundingBox.Width = maxX - minX;
+            boundingBox.Length = maxX - minX;
-            boundingBox.Length = maxY - minY;
+            boundingBox.Width = maxY - minY;
         }
 
         public override Entity OffsetEntity(double distance, OffsetSide side)

OpenNest.Core/Geometry/BoundingBox.cs

@@ -12,8 +12,8 @@ namespace OpenNest.Geometry
 
             double minX = boxes[0].X;
             double minY = boxes[0].Y;
-            double maxX = boxes[0].X + boxes[0].Width;
+            double maxX = boxes[0].Right;
-            double maxY = boxes[0].Y + boxes[0].Length;
+            double maxY = boxes[0].Top;
 
             foreach (var box in boxes)
             {

OpenNest.Core/Geometry/Box.cs

@@ -14,15 +14,15 @@ namespace OpenNest.Geometry
         public Box(double x, double y, double w, double h)
         {
             Location = new Vector(x, y);
-            Width = w;
+            Length = w;
-            Length = h;
+            Width = h;
         }
 
         public Vector Location;
 
         public Vector Center
         {
-            get { return new Vector(X + Width * 0.5, Y + Length * 0.5); }
+            get { return new Vector(X + Length * 0.5, Y + Width * 0.5); }
         }
 
         public Size Size;
@@ -76,12 +76,12 @@ namespace OpenNest.Geometry
 
         public Box Translate(double x, double y)
         {
-            return new Box(X + x, Y + y, Width, Length);
+            return new Box(X + x, Y + y, Length, Width);
         }
 
         public Box Translate(Vector offset)
         {
-            return new Box(X + offset.X, Y + offset.Y, Width, Length);
+            return new Box(X + offset.X, Y + offset.Y, Length, Width);
         }
 
         public double Left
@@ -91,12 +91,12 @@ namespace OpenNest.Geometry
 
         public double Right
         {
-            get { return X + Width; }
+            get { return X + Length; }
         }
 
         public double Top
         {
-            get { return Y + Length; }
+            get { return Y + Width; }
         }
 
         public double Bottom
@@ -207,7 +207,7 @@ namespace OpenNest.Geometry
 
         public Box Offset(double d)
         {
-            return new Box(X - d, Y - d, Width + d * 2, Length + d * 2);
+            return new Box(X - d, Y - d, Length + d * 2, Width + d * 2);
         }
 
         public override string ToString()

OpenNest.Core/Geometry/BoxSplitter.cs

@@ -9,7 +9,7 @@
 
             var x = large.Left;
             var y = small.Top;
-            var w = large.Width;
+            var w = large.Length;
             var h = large.Top - y;
 
             return new Box(x, y, w, h);
@@ -23,7 +23,7 @@
             var x = large.Left;
             var y = large.Bottom;
             var w = small.Left - x;
-            var h = large.Length;
+            var h = large.Width;
 
             return new Box(x, y, w, h);
         }
@@ -35,7 +35,7 @@
 
             var x = large.Left;
             var y = large.Bottom;
-            var w = large.Width;
+            var w = large.Length;
             var h = small.Top - y;
 
             return new Box(x, y, w, h);
@@ -49,7 +49,7 @@
             var x = small.Right;
             var y = large.Bottom;
             var w = large.Right - x;
-            var h = large.Length;
+            var h = large.Width;
 
             return new Box(x, y, w, h);
         }

OpenNest.Core/Geometry/Line.cs

@@ -370,23 +370,23 @@ namespace OpenNest.Geometry
             if (StartPoint.X < EndPoint.X)
             {
                 boundingBox.X = StartPoint.X;
-                boundingBox.Width = EndPoint.X - StartPoint.X;
+                boundingBox.Length = EndPoint.X - StartPoint.X;
             }
             else
             {
                 boundingBox.X = EndPoint.X;
-                boundingBox.Width = StartPoint.X - EndPoint.X;
+                boundingBox.Length = StartPoint.X - EndPoint.X;
             }
 
             if (StartPoint.Y < EndPoint.Y)
             {
                 boundingBox.Y = StartPoint.Y;
-                boundingBox.Length = EndPoint.Y - StartPoint.Y;
+                boundingBox.Width = EndPoint.Y - StartPoint.Y;
             }
             else
             {
                 boundingBox.Y = EndPoint.Y;
-                boundingBox.Length = StartPoint.Y - EndPoint.Y;
+                boundingBox.Width = StartPoint.Y - EndPoint.Y;
             }
         }
 

OpenNest.Core/Geometry/Polygon.cs

@@ -311,8 +311,8 @@ namespace OpenNest.Geometry
 
             boundingBox.X = minX;
             boundingBox.Y = minY;
-            boundingBox.Width = maxX - minX;
+            boundingBox.Length = maxX - minX;
-            boundingBox.Length = maxY - minY;
+            boundingBox.Width = maxY - minY;
         }
 
         public override Entity OffsetEntity(double distance, OffsetSide side)

OpenNest.Core/Part.cs

@@ -277,7 +277,7 @@ namespace OpenNest
             var part = new Part(BaseDrawing, Program,
                 location + offset,
                 new Box(BoundingBox.X + offset.X, BoundingBox.Y + offset.Y,
-                    BoundingBox.Width, BoundingBox.Length));
+                    BoundingBox.Length, BoundingBox.Width));
 
             return part;
         }

OpenNest.Core/Plate.cs

@@ -424,7 +424,7 @@ namespace OpenNest
         {
             var plateBox = new Box();
 
-            // Convention: Size.Length = X axis (horizontal), Size.Width = Y axis (vertical)
+            // Width = Y axis (vertical), Length = X axis (horizontal)
             switch (Quadrant)
             {
                 case 1:
@@ -451,8 +451,8 @@ namespace OpenNest
                     return new Box();
             }
 
-            plateBox.Width = Size.Length;
+            plateBox.Width = Size.Width;
-            plateBox.Length = Size.Width;
+            plateBox.Length = Size.Length;
 
             if (!includeParts)
                 return plateBox;
@@ -468,11 +468,11 @@ namespace OpenNest
                 ? partsBox.Bottom
                 : plateBox.Bottom;
 
-            boundingBox.Width = partsBox.Right > plateBox.Right
+            boundingBox.Length = partsBox.Right > plateBox.Right
                 ? partsBox.Right - boundingBox.X
                 : plateBox.Right - boundingBox.X;
 
-            boundingBox.Length = partsBox.Top > plateBox.Top
+            boundingBox.Width = partsBox.Top > plateBox.Top
                 ? partsBox.Top - boundingBox.Y
                 : plateBox.Top - boundingBox.Y;
 
@@ -489,8 +489,8 @@ namespace OpenNest
 
             box.X += EdgeSpacing.Left;
             box.Y += EdgeSpacing.Bottom;
-            box.Width -= EdgeSpacing.Left + EdgeSpacing.Right;
+            box.Length -= EdgeSpacing.Left + EdgeSpacing.Right;
-            box.Length -= EdgeSpacing.Top + EdgeSpacing.Bottom;
+            box.Width -= EdgeSpacing.Top + EdgeSpacing.Bottom;
 
             return box;
         }

OpenNest.Core/Splitting/AutoSplitCalculator.cs

@@ -13,8 +13,8 @@ public static class AutoSplitCalculator
 
         var lines = new List<SplitLine>();
 
-        var verticalSplits = usableWidth > 0 ? (int)System.Math.Ceiling(partBounds.Width / usableWidth) - 1 : 0;
+        var verticalSplits = usableWidth > 0 ? (int)System.Math.Ceiling(partBounds.Length / usableWidth) - 1 : 0;
-        var horizontalSplits = usableHeight > 0 ? (int)System.Math.Ceiling(partBounds.Length / usableHeight) - 1 : 0;
+        var horizontalSplits = usableHeight > 0 ? (int)System.Math.Ceiling(partBounds.Width / usableHeight) - 1 : 0;
 
         if (verticalSplits < 0) verticalSplits = 0;
         if (horizontalSplits < 0) horizontalSplits = 0;
@@ -34,14 +34,14 @@ public static class AutoSplitCalculator
 
         if (verticalPieces > 1)
         {
-            var spacing = partBounds.Width / verticalPieces;
+            var spacing = partBounds.Length / verticalPieces;
             for (var i = 1; i < verticalPieces; i++)
                 lines.Add(new SplitLine(partBounds.X + spacing * i, CutOffAxis.Vertical));
         }
 
         if (horizontalPieces > 1)
         {
-            var spacing = partBounds.Length / horizontalPieces;
+            var spacing = partBounds.Width / horizontalPieces;
             for (var i = 1; i < horizontalPieces; i++)
                 lines.Add(new SplitLine(partBounds.Y + spacing * i, CutOffAxis.Horizontal));
         }

OpenNest.Engine/DefaultNestEngine.cs

@@ -203,7 +203,7 @@ namespace OpenNest
             if (newWidth >= workArea.Width && newLength >= workArea.Length)
                 return workArea;
 
-            return new Box(workArea.X, workArea.Y, newWidth, newLength);
+            return new Box(workArea.X, workArea.Y, newLength, newWidth);
         }
 
         private List<Part> RunFillPipeline(NestItem item, Box workArea,

OpenNest.Engine/Fill/BestCombination.cs

@@ -2,13 +2,15 @@
 
 namespace OpenNest
 {
+    internal record CombinationResult(bool Found, int Count1, int Count2);
+
     internal static class BestCombination
     {
-        public static bool FindFrom2(double length1, double length2, double overallLength, out int count1, out int count2)
+        public static CombinationResult FindFrom2(double length1, double length2, double overallLength)
         {
             overallLength += Tolerance.Epsilon;
-            count1 = 0;
+            var count1 = 0;
-            count2 = 0;
+            var count2 = 0;
 
             var maxCount1 = (int)System.Math.Floor(overallLength / length1);
             var bestRemnant = overallLength + 1;
@@ -30,7 +32,7 @@ namespace OpenNest
                     break;
             }
 
-            return count1 > 0 || count2 > 0;
+            return new CombinationResult(count1 > 0 || count2 > 0, count1, count2);
         }
     }
 }

OpenNest.Engine/Fill/FillExtents.cs

@@ -96,7 +96,7 @@ namespace OpenNest.Engine.Fill
             var boundary2 = new PartBoundary(part2, halfSpacing);
 
             // Position part2 to the right of part1 at bounding box width distance.
-            var startOffset = part1.BoundingBox.Width + part2.BoundingBox.Width + partSpacing;
+            var startOffset = part1.BoundingBox.Length + part2.BoundingBox.Length + partSpacing;
             part2.Offset(startOffset, 0);
             part2.UpdateBounds();
 
@@ -135,7 +135,7 @@ namespace OpenNest.Engine.Fill
 
             // Compute vertical copy distance using bounding boxes as starting point,
             // then slide down to find true geometry distance.
-            var pairHeight = pair.Bbox.Length;
+            var pairHeight = pair.Bbox.Width;
             var testOffset = new Vector(0, pairHeight);
 
             // Create test parts for slide distance measurement.
@@ -218,7 +218,7 @@ namespace OpenNest.Engine.Fill
 
         private List<Part> AdjustColumn(PartPair pair, List<Part> column, CancellationToken token)
         {
-            var originalPairWidth = pair.Bbox.Width;
+            var originalPairWidth = pair.Bbox.Length;
 
             for (var iteration = 0; iteration < MaxIterations; iteration++)
             {
@@ -294,7 +294,7 @@ namespace OpenNest.Engine.Fill
             // Check if the pair got wider.
             var newBbox = PairBbox(p1, p2);
 
-            if (newBbox.Width > originalPairWidth + Tolerance.Epsilon)
+            if (newBbox.Length > originalPairWidth + Tolerance.Epsilon)
                 return null;
 
             return AnchorToWorkArea(p1, p2);

OpenNest.Engine/Fill/FillLinear.cs

@@ -11,7 +11,7 @@ namespace OpenNest.Engine.Fill
         public FillLinear(Box workArea, double partSpacing)
         {
             PartSpacing = partSpacing;
-            WorkArea = new Box(workArea.X, workArea.Y, workArea.Width, workArea.Length);
+            WorkArea = new Box(workArea.X, workArea.Y, workArea.Length, workArea.Width);
         }
 
         public Box WorkArea { get; }
@@ -41,7 +41,7 @@ namespace OpenNest.Engine.Fill
 
         private static double GetDimension(Box box, NestDirection direction)
         {
-            return direction == NestDirection.Horizontal ? box.Width : box.Length;
+            return direction == NestDirection.Horizontal ? box.Length : box.Width;
         }
 
         private static double GetStart(Box box, NestDirection direction)

OpenNest.Engine/Fill/PairFiller.cs

@@ -175,8 +175,8 @@ namespace OpenNest.Engine.Fill
             var newTop = remaining.Max(p => p.BoundingBox.Top);
 
             return new Box(workArea.X, workArea.Y,
-                workArea.Width,
+                workArea.Length,
-                System.Math.Min(newTop - workArea.Y, workArea.Length));
+                System.Math.Min(newTop - workArea.Y, workArea.Width));
         }
 
         private List<Part> EvaluateCandidate(BestFitResult candidate, Drawing drawing,
@@ -271,8 +271,8 @@ namespace OpenNest.Engine.Fill
             var topHeight = System.Math.Max(0, workArea.Top - gridBox.Top);
             var rightWidth = System.Math.Max(0, workArea.Right - gridBox.Right);
 
-            var topArea = workArea.Width * topHeight;
+            var topArea = workArea.Length * topHeight;
-            var rightArea = rightWidth * System.Math.Min(gridBox.Top - workArea.Y, workArea.Length);
+            var rightArea = rightWidth * System.Math.Min(gridBox.Top - workArea.Y, workArea.Width);
             var remnantArea = topArea + rightArea;
 
             return (int)(remnantArea * maxUtilization / partArea) + 1;
@@ -292,7 +292,7 @@ namespace OpenNest.Engine.Fill
             var topLength = workArea.Top - topY;
             if (topLength >= minDim)
             {
-                var topBox = new Box(workArea.X, topY, workArea.Width, topLength);
+                var topBox = new Box(workArea.X, topY, workArea.Length, topLength);
                 var parts = FillRemnantBox(drawing, topBox, token);
                 if (parts != null && parts.Count > (bestRemnant?.Count ?? 0))
                     bestRemnant = parts;
@@ -303,7 +303,7 @@ namespace OpenNest.Engine.Fill
             var rightWidth = workArea.Right - rightX;
             if (rightWidth >= minDim)
             {
-                var rightBox = new Box(rightX, workArea.Y, rightWidth, workArea.Length);
+                var rightBox = new Box(rightX, workArea.Y, rightWidth, workArea.Width);
                 var parts = FillRemnantBox(drawing, rightBox, token);
                 if (parts != null && parts.Count > (bestRemnant?.Count ?? 0))
                     bestRemnant = parts;

OpenNest.Engine/Fill/PartBoundary.cs

@@ -24,7 +24,7 @@ namespace OpenNest.Engine.Fill
         public PartBoundary(Part part, double spacing)
         {
             var entities = ConvertProgram.ToGeometry(part.Program)
-                .Where(e => e.Layer != SpecialLayers.Rapid)
+                .Where(e => e.Layer == SpecialLayers.Cut)
                 .ToList();
 
             var definedShape = new ShapeProfile(entities);

OpenNest.Engine/Fill/PatternTiler.cs

@@ -13,15 +13,15 @@ namespace OpenNest.Engine.Fill
             var cellBox = cell.GetBoundingBox();
             var halfSpacing = partSpacing / 2;
 
-            var cellWidth = cellBox.Width + partSpacing;
+            var cellW = cellBox.Width + partSpacing;
-            var cellHeight = cellBox.Length + partSpacing;
+            var cellL = cellBox.Length + partSpacing;
 
-            if (cellWidth <= 0 || cellHeight <= 0)
+            if (cellW <= 0 || cellL <= 0)
                 return new List<Part>();
 
-            // Size.Width = X-axis, Size.Length = Y-axis
+            // Width = Y axis, Length = X axis
-            var cols = (int)System.Math.Floor(plateSize.Width / cellWidth);
+            var cols = (int)System.Math.Floor(plateSize.Length / cellL);
-            var rows = (int)System.Math.Floor(plateSize.Length / cellHeight);
+            var rows = (int)System.Math.Floor(plateSize.Width / cellW);
 
             if (cols <= 0 || rows <= 0)
                 return new List<Part>();
@@ -37,7 +37,7 @@ namespace OpenNest.Engine.Fill
             {
                 for (var col = 0; col < cols; col++)
                 {
-                    var tileOffset = baseOffset + new Vector(col * cellWidth, row * cellHeight);
+                    var tileOffset = baseOffset + new Vector(col * cellL, row * cellW);
 
                     foreach (var part in cell)
                     {

OpenNest.Engine/Fill/RemnantFinder.cs

@@ -304,10 +304,10 @@ namespace OpenNest.Engine.Fill
 
             // Edge extensions (priority 1).
             if (remnant.Right > envelope.Right + eps)
-                TryAdd(results, envelope.Right, remnant.Bottom, remnant.Right - envelope.Right, remnant.Length, 1, minDim);
+                TryAdd(results, envelope.Right, remnant.Bottom, remnant.Right - envelope.Right, remnant.Width, 1, minDim);
 
             if (remnant.Left < envelope.Left - eps)
-                TryAdd(results, remnant.Left, remnant.Bottom, envelope.Left - remnant.Left, remnant.Length, 1, minDim);
+                TryAdd(results, remnant.Left, remnant.Bottom, envelope.Left - remnant.Left, remnant.Width, 1, minDim);
 
             if (remnant.Top > envelope.Top + eps)
                 TryAdd(results, innerLeft, envelope.Top, innerRight - innerLeft, remnant.Top - envelope.Top, 1, minDim);

OpenNest.Engine/Fill/StripeFiller.cs

@@ -201,8 +201,8 @@ public class StripeFiller
     private static Box MakeStripeBox(Box workArea, double perpDim, NestDirection primaryAxis)
     {
         return primaryAxis == NestDirection.Horizontal
-            ? new Box(workArea.X, workArea.Y, workArea.Width, perpDim)
+            ? new Box(workArea.X, workArea.Y, workArea.Length, perpDim)
-            : new Box(workArea.X, workArea.Y, perpDim, workArea.Length);
+            : new Box(workArea.X, workArea.Y, perpDim, workArea.Width);
     }
 
     private List<Part> FillRemnant(List<Part> gridParts, NestDirection primaryAxis)
@@ -224,7 +224,7 @@ public class StripeFiller
             var remnantLength = workArea.Top - remnantY;
             if (remnantLength < minDim)
                 return null;
-            remnantBox = new Box(workArea.X, remnantY, workArea.Width, remnantLength);
+            remnantBox = new Box(workArea.X, remnantY, workArea.Length, remnantLength);
         }
         else
         {
@@ -232,7 +232,7 @@ public class StripeFiller
             var remnantWidth = workArea.Right - remnantX;
             if (remnantWidth < minDim)
                 return null;
-            remnantBox = new Box(remnantX, workArea.Y, remnantWidth, workArea.Length);
+            remnantBox = new Box(remnantX, workArea.Y, remnantWidth, workArea.Width);
         }
 
         Debug.WriteLine($"[StripeFiller] Remnant box: {remnantBox.Width:F2}x{remnantBox.Length:F2}");
@@ -324,7 +324,7 @@ public class StripeFiller
     {
         var box = FillHelpers.BuildRotatedPattern(patternParts, 0).BoundingBox;
         var span0 = GetDimension(box, axis);
-        var perpSpan0 = axis == NestDirection.Horizontal ? box.Length : box.Width;
+        var perpSpan0 = axis == NestDirection.Horizontal ? box.Width : box.Length;
 
         if (span0 <= perpSpan0)
             return 0;
@@ -388,7 +388,7 @@ public class StripeFiller
             var rotated = FillHelpers.BuildRotatedPattern(patternParts, currentAngle);
             var pairSpan = GetDimension(rotated.BoundingBox, axis);
             var perpDim = axis == NestDirection.Horizontal
-                ? rotated.BoundingBox.Length : rotated.BoundingBox.Width;
+                ? rotated.BoundingBox.Width : rotated.BoundingBox.Length;
 
             if (pairSpan + spacing <= 0)
                 break;
@@ -472,13 +472,13 @@ public class StripeFiller
     {
         var rotated = FillHelpers.BuildRotatedPattern(patternParts, angle);
         return axis == NestDirection.Horizontal
-            ? rotated.BoundingBox.Width
+            ? rotated.BoundingBox.Length
-            : rotated.BoundingBox.Length;
+            : rotated.BoundingBox.Width;
     }
 
     private static double GetDimension(Box box, NestDirection axis)
     {
-        return axis == NestDirection.Horizontal ? box.Width : box.Length;
+        return axis == NestDirection.Horizontal ? box.Length : box.Width;
     }
 
     private static bool HasOverlappingParts(List<Part> parts) =>

OpenNest.Engine/HorizontalRemnantEngine.cs

@@ -38,7 +38,7 @@ namespace OpenNest
             var bb = item.Drawing.Program.BoundingBox();
             var cos = System.Math.Abs(System.Math.Cos(angle));
             var sin = System.Math.Abs(System.Math.Sin(angle));
-            return bb.Length * cos + bb.Width * sin;
+            return bb.Width * cos + bb.Length * sin;
         }
     }
 }

OpenNest.Engine/ML/FeatureExtractor.cs

@@ -47,7 +47,7 @@ namespace OpenNest.Engine.ML
             {
                 Area = drawing.Area,
                 Convexity = drawing.Area / (hullArea > 0 ? hullArea : 1.0),
-                AspectRatio = bb.Width / (bb.Length > 0 ? bb.Length : 1.0),
+                AspectRatio = bb.Length / (bb.Width > 0 ? bb.Width : 1.0),
                 BoundingBoxFill = drawing.Area / (bb.Area() > 0 ? bb.Area() : 1.0),
                 VertexCount = polygon.Vertices.Count,
                 Bitmask = GenerateBitmask(polygon, 32)
@@ -72,8 +72,8 @@ namespace OpenNest.Engine.ML
                 for (int x = 0; x < size; x++)
                 {
                     // Map grid coordinate (0..size) to bounding box coordinate
-                    var px = bb.Left + (x + 0.5) * (bb.Width / size);
+                    var px = bb.Left + (x + 0.5) * (bb.Length / size);
-                    var py = bb.Bottom + (y + 0.5) * (bb.Length / size);
+                    var py = bb.Bottom + (y + 0.5) * (bb.Width / size);
 
                     if (polygon.ContainsPoint(new Vector(px, py)))
                     {

OpenNest.Engine/RectanglePacking/FillBestFit.cs

@@ -29,11 +29,15 @@ namespace OpenNest.RectanglePacking
                 Bin.Items.AddRange(bin1.Items);
             else
                 Bin.Items.AddRange(bin2.Items);
-        }
+        }   
+
 
         public override void Fill(Item item, int maxCount)
         {
-            throw new NotImplementedException();
+            Fill(item);
+
+            if (Bin.Items.Count > maxCount)
+                Bin.Items.RemoveRange(maxCount, Bin.Items.Count - maxCount);
         }
 
         private Bin BestFitHorizontal(Item item) => BestFitAxis(item, horizontal: true);
@@ -44,14 +48,18 @@ namespace OpenNest.RectanglePacking
         {
             var bin = Bin.Clone() as Bin;
 
-            var primarySize = horizontal ? item.Width : item.Length;
+            var primarySize = horizontal ? item.Length : item.Width;
-            var secondarySize = horizontal ? item.Length : item.Width;
+            var secondarySize = horizontal ? item.Width : item.Length;
-            var binPrimary = horizontal ? bin.Width : Bin.Length;
+            var binPrimary = horizontal ? bin.Length : Bin.Width;
-            var binSecondary = horizontal ? bin.Length : Bin.Width;
+            var binSecondary = horizontal ? bin.Width : Bin.Length;
 
-            if (!BestCombination.FindFrom2(primarySize, secondarySize, binPrimary, out var normalPrimary, out var rotatePrimary))
+            var combo = BestCombination.FindFrom2(primarySize, secondarySize, binPrimary);
+            if (!combo.Found)
                 return bin;
 
+            var normalPrimary = combo.Count1;
+            var rotatePrimary = combo.Count2;
+
             var normalSecondary = (int)System.Math.Floor((binSecondary + Tolerance.Epsilon) / secondarySize);
             var rotateSecondary = (int)System.Math.Floor((binSecondary + Tolerance.Epsilon) / primarySize);
 
@@ -67,9 +75,9 @@ namespace OpenNest.RectanglePacking
             bin.Items.AddRange(FillGrid(item, normalRows, normalCols, int.MaxValue));
 
             if (horizontal)
-                item.Location.X += item.Width * normalPrimary;
+                item.Location.X += item.Length * normalPrimary;
             else
-                item.Location.Y += item.Length * normalPrimary;
+                item.Location.Y += item.Width * normalPrimary;
 
             item.Rotate();
 

OpenNest.Engine/RectanglePacking/FillEngine.cs

@@ -27,8 +27,8 @@ namespace OpenNest.RectanglePacking
             {
                 for (var j = 0; j < innerCount; j++)
                 {
-                    var x = (columnMajor ? i : j) * item.Width + item.X;
+                    var x = (columnMajor ? i : j) * item.Length + item.X;
-                    var y = (columnMajor ? j : i) * item.Length + item.Y;
+                    var y = (columnMajor ? j : i) * item.Width + item.Y;
 
                     var clone = item.Clone() as Item;
                     clone.Location = new Vector(x, y);

OpenNest.Engine/RectanglePacking/FillNoRotation.cs

@@ -14,16 +14,16 @@ namespace OpenNest.RectanglePacking
 
         public override void Fill(Item item)
         {
-            var ycount = (int)System.Math.Floor((Bin.Length + Tolerance.Epsilon) / item.Length);
+            var ycount = (int)System.Math.Floor((Bin.Width + Tolerance.Epsilon) / item.Width);
-            var xcount = (int)System.Math.Floor((Bin.Width + Tolerance.Epsilon) / item.Width);
+            var xcount = (int)System.Math.Floor((Bin.Length + Tolerance.Epsilon) / item.Length);
 
             for (int i = 0; i < xcount; i++)
             {
-                var x = item.Width * i + Bin.X;
+                var x = item.Length * i + Bin.X;
 
                 for (int j = 0; j < ycount; j++)
                 {
-                    var y = item.Length * j + Bin.Y;
+                    var y = item.Width * j + Bin.Y;
 
                     var addedItem = item.Clone() as Item;
                     addedItem.Location = new Vector(x, y);
@@ -35,8 +35,8 @@ namespace OpenNest.RectanglePacking
 
         public override void Fill(Item item, int maxCount)
         {
-            var ycount = (int)System.Math.Floor((Bin.Length + Tolerance.Epsilon) / item.Length);
+            var ycount = (int)System.Math.Floor((Bin.Width + Tolerance.Epsilon) / item.Width);
-            var xcount = (int)System.Math.Floor((Bin.Width + Tolerance.Epsilon) / item.Width);
+            var xcount = (int)System.Math.Floor((Bin.Length + Tolerance.Epsilon) / item.Length);
             var count = ycount * xcount;
 
             if (count <= maxCount)

OpenNest.Engine/RectanglePacking/FillSpiral.cs

@@ -0,0 +1,83 @@
+using OpenNest.Geometry;
+using OpenNest.Math;
+
+namespace OpenNest.RectanglePacking
+{
+    internal class FillSpiral : FillEngine
+    {
+        public Box CenterRemnant { get; private set; }
+
+        public FillSpiral(Bin bin)
+            : base(bin)
+        {
+        }
+
+        public override void Fill(Item item)
+        {
+            Fill(item, int.MaxValue);
+        }
+
+        public override void Fill(Item item, int maxCount)
+        {
+            if (item == null) return;
+
+            // Width = Y axis, Length = X axis
+            var comboY = BestCombination.FindFrom2(item.Width, item.Length, Bin.Width);
+            var comboX = BestCombination.FindFrom2(item.Length, item.Width, Bin.Length);
+
+            if (!comboY.Found || !comboX.Found)
+                return;
+
+            var q14size = new Size(
+                item.Width * comboY.Count1,
+                item.Length * comboX.Count1);
+            var q23size = new Size(
+                item.Length * comboY.Count2,
+                item.Width * comboX.Count2);
+
+            if ((q14size.Width > q23size.Width && q14size.Length > q23size.Length) ||
+                (q23size.Width > q14size.Width && q23size.Length > q14size.Length))
+                return; // cant do an efficient spiral fill
+
+            // Q1: normal orientation at bin origin
+            item.Location = Bin.Location;
+            var q1 = FillGrid(item, comboY.Count1, comboX.Count1, maxCount);
+            Bin.Items.AddRange(q1);
+
+            // Q2: rotated, above Q1
+            item.Rotate();
+            item.Location = new Vector(Bin.X, Bin.Y + q14size.Width);
+            var q2 = FillGrid(item, comboY.Count2, comboX.Count2, maxCount - Bin.Items.Count);
+            Bin.Items.AddRange(q2);
+
+            // Q3: rotated, right of Q1
+            item.Location = new Vector(Bin.X + q14size.Length, Bin.Y);
+            var q3 = FillGrid(item, comboY.Count2, comboX.Count2, maxCount - Bin.Items.Count);
+            Bin.Items.AddRange(q3);
+
+            // Q4: normal orientation, diagonal from Q1
+            item.Rotate();
+            item.Location = new Vector(
+                Bin.X + q23size.Length,
+                Bin.Y + q23size.Width);
+            var q4 = FillGrid(item, comboY.Count1, comboX.Count1, maxCount);
+            Bin.Items.AddRange(q4);
+
+            // Compute center remnant — the rectangular gap between the 4 quadrants
+            // Only valid when all 4 quadrants have items; otherwise the "center"
+            // overlaps an occupied quadrant and recursion never terminates.
+            var centerW = System.Math.Abs(q14size.Length - q23size.Length);
+            var centerH = System.Math.Abs(q14size.Width - q23size.Width);
+
+            if (comboY.Count1 > 0 && comboY.Count2 > 0 && comboX.Count1 > 0 && comboX.Count2 > 0
+                && centerW > Tolerance.Epsilon && centerH > Tolerance.Epsilon)
+            {
+                CenterRemnant = new Box(
+                    Bin.X + System.Math.Min(q14size.Length, q23size.Length),
+                    Bin.Y + System.Math.Min(q14size.Width, q23size.Width),
+                    centerW,
+                    centerH);
+            }
+        }
+    }
+}

OpenNest.Engine/RectanglePacking/Item.cs

@@ -37,8 +37,8 @@ namespace OpenNest.RectanglePacking
 
             double minX = items[0].X;
             double minY = items[0].Y;
-            double maxX = items[0].X + items[0].Width;
+            double maxX = items[0].Right;
-            double maxY = items[0].Y + items[0].Length;
+            double maxY = items[0].Top;
 
             foreach (var box in items)
             {

OpenNest.Engine/RectanglePacking/PackFirstFitDecreasing.cs

@@ -16,11 +16,11 @@ namespace OpenNest.RectanglePacking
 
         public override void Pack(List<Item> items)
         {
-            items = items.OrderBy(i => -i.Length).ToList();
+            items = items.OrderBy(i => -i.Width).ToList();
 
             foreach (var item in items)
             {
-                if (item.Length > Bin.Length)
+                if (item.Width > Bin.Width)
                     continue;
 
                 var level = FindLevel(item);
@@ -36,10 +36,10 @@ namespace OpenNest.RectanglePacking
         {
             foreach (var level in levels)
             {
-                if (level.Height < item.Length)
+                if (level.Height < item.Width)
                     continue;
 
-                if (level.RemainingWidth < item.Width)
+                if (level.RemainingLength < item.Length)
                     continue;
 
                 return level;
@@ -58,12 +58,12 @@ namespace OpenNest.RectanglePacking
 
             var remaining = Bin.Top - y;
 
-            if (remaining < item.Length)
+            if (remaining < item.Width)
                 return null;
 
             var level = new Level(Bin);
             level.Y = y;
-            level.Height = item.Length;
+            level.Height = item.Width;
 
             levels.Add(level);
 
@@ -93,9 +93,9 @@ namespace OpenNest.RectanglePacking
                 set { NextItemLocation.Y = value; }
             }
 
-            public double Width
+            public double LevelLength
             {
-                get { return Parent.Width; }
+                get { return Parent.Length; }
             }
 
             public double Height { get; set; }
@@ -105,9 +105,9 @@ namespace OpenNest.RectanglePacking
                 get { return Y + Height; }
             }
 
-            public double RemainingWidth
+            public double RemainingLength
             {
-                get { return X + Width - NextItemLocation.X; }
+                get { return X + LevelLength - NextItemLocation.X; }
             }
 
             public void AddItem(Item item)
@@ -115,7 +115,7 @@ namespace OpenNest.RectanglePacking
                 item.Location = NextItemLocation;
                 Parent.Items.Add(item);
 
-                NextItemLocation = new Vector(NextItemLocation.X + item.Width, NextItemLocation.Y);
+                NextItemLocation = new Vector(NextItemLocation.X + item.Length, NextItemLocation.Y);
             }
         }
     }

OpenNest.Engine/RectanglePacking/RectFill.cs

@@ -0,0 +1,44 @@
+using OpenNest.Geometry;
+
+namespace OpenNest.RectanglePacking
+{
+    internal static class RectFill
+    {
+        public static void FillBest(Bin bin, Item item, int maxCount = int.MaxValue)
+        {
+            var spiralBin = bin.Clone() as Bin;
+            var spiral = new FillSpiral(spiralBin);
+            spiral.Fill(item, maxCount);
+
+            // Recursively fill the center remnant of the spiral
+            if (spiralBin.Items.Count > 0 && spiral.CenterRemnant != null)
+            {
+                var center = spiral.CenterRemnant;
+                var fitsNormal = item.Length <= center.Length && item.Width <= center.Width;
+                var fitsRotated = item.Width <= center.Length && item.Length <= center.Width;
+
+                if (fitsNormal || fitsRotated)
+                {
+                    var remaining = maxCount - spiralBin.Items.Count;
+                    FillBest(center.Location, center.Size, spiralBin, item, remaining);
+                }
+            }
+
+            var bestFitBin = bin.Clone() as Bin;
+            new FillBestFit(bestFitBin).Fill(item, maxCount);
+
+            var winner = spiralBin.Items.Count >= bestFitBin.Items.Count ? spiralBin : bestFitBin;
+            bin.Items.AddRange(winner.Items);
+        }
+
+        public static void FillBest(Vector location, Size size, Bin target, Item item, int maxCount)
+        {
+            if (size.Width <= 0 || size.Length <= 0 || maxCount <= 0)
+                return;
+
+            var bin = new Bin { Location = location, Size = size };
+            FillBest(bin, item, maxCount);
+            target.Items.AddRange(bin.Items);
+        }
+    }
+}

OpenNest.Engine/Strategies/RectBestFitStrategy.cs

@@ -14,8 +14,7 @@ namespace OpenNest.Engine.Strategies
             var binItem = BinConverter.ToItem(context.Item, context.Plate.PartSpacing);
             var bin = BinConverter.CreateBin(context.WorkArea, context.Plate.PartSpacing);
 
-            var engine = new FillBestFit(bin);
+            RectFill.FillBest(bin, binItem);
-            engine.Fill(binItem);
 
             return BinConverter.ToParts(bin, new List<NestItem> { context.Item });
         }

OpenNest.Engine/VerticalRemnantEngine.cs

@@ -36,7 +36,7 @@ namespace OpenNest
             var bb = item.Drawing.Program.BoundingBox();
             var cos = System.Math.Abs(System.Math.Cos(angle));
             var sin = System.Math.Abs(System.Math.Sin(angle));
-            return bb.Width * cos + bb.Length * sin;
+            return bb.Length * cos + bb.Width * sin;
         }
     }
 }

OpenNest.Tests/Engine/NestProgressTests.cs

@@ -49,7 +49,7 @@ public class NestProgressTests
         var parts = new List<Part>
         {
             TestHelpers.MakePartAt(0, 0, 5),
-            TestHelpers.MakePartAt(10, 0, 5),
+            TestHelpers.MakePartAt(0, 10, 5),
         };
         var progress = new NestProgress { BestParts = parts };
         Assert.Equal(15, progress.NestedWidth, precision: 4);
@@ -61,7 +61,7 @@ public class NestProgressTests
         var parts = new List<Part>
         {
             TestHelpers.MakePartAt(0, 0, 5),
-            TestHelpers.MakePartAt(0, 10, 5),
+            TestHelpers.MakePartAt(10, 0, 5),
         };
         var progress = new NestProgress { BestParts = parts };
         Assert.Equal(15, progress.NestedLength, precision: 4);

OpenNest.Tests/Fill/BestCombinationTests.cs

@@ -6,61 +6,61 @@ public class BestCombinationTests
     public void BothFit_FindsZeroRemnant()
     {
         // 100 = 0*30 + 5*20 (algorithm iterates from countLength1=0, finds zero remnant first)
-        var result = BestCombination.FindFrom2(30, 20, 100, out var c1, out var c2);
+        var result = BestCombination.FindFrom2(30, 20, 100);
 
-        Assert.True(result);
+        Assert.True(result.Found);
-        Assert.Equal(0.0, 100.0 - (c1 * 30.0 + c2 * 20.0), 5);
+        Assert.Equal(0.0, 100.0 - (result.Count1 * 30.0 + result.Count2 * 20.0), 5);
     }
 
     [Fact]
     public void OnlyLength1Fits_ReturnsMaxCount1()
     {
-        var result = BestCombination.FindFrom2(10, 200, 50, out var c1, out var c2);
+        var result = BestCombination.FindFrom2(10, 200, 50);
 
-        Assert.True(result);
+        Assert.True(result.Found);
-        Assert.Equal(5, c1);
+        Assert.Equal(5, result.Count1);
-        Assert.Equal(0, c2);
+        Assert.Equal(0, result.Count2);
     }
 
     [Fact]
     public void OnlyLength2Fits_ReturnsMaxCount2()
     {
-        var result = BestCombination.FindFrom2(200, 10, 50, out var c1, out var c2);
+        var result = BestCombination.FindFrom2(200, 10, 50);
 
-        Assert.True(result);
+        Assert.True(result.Found);
-        Assert.Equal(0, c1);
+        Assert.Equal(0, result.Count1);
-        Assert.Equal(5, c2);
+        Assert.Equal(5, result.Count2);
     }
 
     [Fact]
     public void NeitherFits_ReturnsFalse()
     {
-        var result = BestCombination.FindFrom2(100, 200, 50, out var c1, out var c2);
+        var result = BestCombination.FindFrom2(100, 200, 50);
 
-        Assert.False(result);
+        Assert.False(result.Found);
-        Assert.Equal(0, c1);
+        Assert.Equal(0, result.Count1);
-        Assert.Equal(0, c2);
+        Assert.Equal(0, result.Count2);
     }
 
     [Fact]
     public void Length1FillsExactly_ZeroRemnant()
     {
-        var result = BestCombination.FindFrom2(25, 10, 100, out var c1, out var c2);
+        var result = BestCombination.FindFrom2(25, 10, 100);
 
-        Assert.True(result);
+        Assert.True(result.Found);
-        Assert.Equal(0.0, 100.0 - (c1 * 25.0 + c2 * 10.0), 5);
+        Assert.Equal(0.0, 100.0 - (result.Count1 * 25.0 + result.Count2 * 10.0), 5);
     }
 
     [Fact]
     public void MixMinimizesRemnant()
     {
         // 7 and 3 into 20: best is 2*7 + 2*3 = 20 (zero remnant)
-        var result = BestCombination.FindFrom2(7, 3, 20, out var c1, out var c2);
+        var result = BestCombination.FindFrom2(7, 3, 20);
 
-        Assert.True(result);
+        Assert.True(result.Found);
-        Assert.Equal(2, c1);
+        Assert.Equal(2, result.Count1);
-        Assert.Equal(2, c2);
+        Assert.Equal(2, result.Count2);
-        Assert.True(c1 * 7 + c2 * 3 <= 20);
+        Assert.True(result.Count1 * 7 + result.Count2 * 3 <= 20);
     }
 
     [Fact]
@@ -68,28 +68,28 @@ public class BestCombinationTests
     {
         // 6 and 5 into 17:
         //   all length1: 2*6=12, remnant=5 -> actually 2*6+1*5=17 perfect
-        var result = BestCombination.FindFrom2(6, 5, 17, out var c1, out var c2);
+        var result = BestCombination.FindFrom2(6, 5, 17);
 
-        Assert.True(result);
+        Assert.True(result.Found);
-        Assert.Equal(0.0, 17.0 - (c1 * 6.0 + c2 * 5.0), 5);
+        Assert.Equal(0.0, 17.0 - (result.Count1 * 6.0 + result.Count2 * 5.0), 5);
     }
 
     [Fact]
     public void EqualLengths_FillsWithLength1()
     {
-        var result = BestCombination.FindFrom2(10, 10, 50, out var c1, out var c2);
+        var result = BestCombination.FindFrom2(10, 10, 50);
 
-        Assert.True(result);
+        Assert.True(result.Found);
-        Assert.Equal(5, c1 + c2);
+        Assert.Equal(5, result.Count1 + result.Count2);
     }
 
     [Fact]
     public void SmallLengths_LargeOverall()
     {
-        var result = BestCombination.FindFrom2(3, 7, 100, out var c1, out var c2);
+        var result = BestCombination.FindFrom2(3, 7, 100);
 
-        Assert.True(result);
+        Assert.True(result.Found);
-        var used = c1 * 3.0 + c2 * 7.0;
+        var used = result.Count1 * 3.0 + result.Count2 * 7.0;
         Assert.True(used <= 100);
         Assert.True(100 - used < 3); // remnant less than smallest piece
     }
@@ -100,41 +100,41 @@ public class BestCombinationTests
         // length1=9, length2=5, overall=10:
         //   length1 alone: 1*9=9 remnant=1
         //   length2 alone: 2*5=10 remnant=0
-        var result = BestCombination.FindFrom2(9, 5, 10, out var c1, out var c2);
+        var result = BestCombination.FindFrom2(9, 5, 10);
 
-        Assert.True(result);
+        Assert.True(result.Found);
-        Assert.Equal(0, c1);
+        Assert.Equal(0, result.Count1);
-        Assert.Equal(2, c2);
+        Assert.Equal(2, result.Count2);
     }
 
     [Fact]
     public void FractionalLengths_WorkCorrectly()
     {
-        var result = BestCombination.FindFrom2(2.5, 3.5, 12, out var c1, out var c2);
+        var result = BestCombination.FindFrom2(2.5, 3.5, 12);
 
-        Assert.True(result);
+        Assert.True(result.Found);
-        var used = c1 * 2.5 + c2 * 3.5;
+        var used = result.Count1 * 2.5 + result.Count2 * 3.5;
         Assert.True(used <= 12.0 + 0.001);
     }
 
     [Fact]
     public void OverallExactlyOneOfEach()
     {
-        var result = BestCombination.FindFrom2(40, 60, 100, out var c1, out var c2);
+        var result = BestCombination.FindFrom2(40, 60, 100);
 
-        Assert.True(result);
+        Assert.True(result.Found);
-        Assert.Equal(1, c1);
+        Assert.Equal(1, result.Count1);
-        Assert.Equal(1, c2);
+        Assert.Equal(1, result.Count2);
     }
 
     [Fact]
     public void OverallSmallerThanEither_ReturnsFalse()
     {
-        var result = BestCombination.FindFrom2(10, 20, 5, out var c1, out var c2);
+        var result = BestCombination.FindFrom2(10, 20, 5);
 
-        Assert.False(result);
+        Assert.False(result.Found);
-        Assert.Equal(0, c1);
+        Assert.Equal(0, result.Count1);
-        Assert.Equal(0, c2);
+        Assert.Equal(0, result.Count2);
     }
 
     [Fact]
@@ -142,9 +142,9 @@ public class BestCombinationTests
     {
         // 4 and 6 into 24: 0*4+4*6=24 or 3*4+2*6=24 or 6*4+0*6=24
         // Algorithm iterates from 0 length1 upward, finds zero remnant and breaks
-        var result = BestCombination.FindFrom2(4, 6, 24, out var c1, out var c2);
+        var result = BestCombination.FindFrom2(4, 6, 24);
 
-        Assert.True(result);
+        Assert.True(result.Found);
-        Assert.Equal(0.0, 24.0 - (c1 * 4.0 + c2 * 6.0), 5);
+        Assert.Equal(0.0, 24.0 - (result.Count1 * 4.0 + result.Count2 * 6.0), 5);
     }
 }

OpenNest.Tests/Fill/PatternTilerTests.cs

@@ -30,8 +30,8 @@ public class PatternTilerTests
 
         foreach (var part in result)
         {
-            Assert.True(part.BoundingBox.Right <= plateSize.Width + 0.001);
+            Assert.True(part.BoundingBox.Right <= plateSize.Length + 0.001);
-            Assert.True(part.BoundingBox.Top <= plateSize.Length + 0.001);
+            Assert.True(part.BoundingBox.Top <= plateSize.Width + 0.001);
             Assert.True(part.BoundingBox.Left >= -0.001);
             Assert.True(part.BoundingBox.Bottom >= -0.001);
         }
@@ -87,8 +87,8 @@ public class PatternTilerTests
 
         var maxRight = result.Max(p => p.BoundingBox.Right);
         var maxTop = result.Max(p => p.BoundingBox.Top);
-        Assert.True(maxRight <= 50.001);
+        Assert.True(maxRight <= 10.001);
-        Assert.True(maxTop <= 10.001);
+        Assert.True(maxTop <= 50.001);
     }
 
     [Fact]

OpenNest.Tests/Fill/RemnantFinderTests.cs

@@ -108,8 +108,8 @@ public class RemnantFinderTests
         var remnants = finder.FindRemnants();
 
         var gap = remnants.FirstOrDefault(r =>
-            r.Width >= 19.9 && r.Width <= 20.1 &&
+            r.Length >= 19.9 && r.Length <= 20.1 &&
-            r.Length >= 99.9);
+            r.Width >= 99.9);
         Assert.NotNull(gap);
     }
 
@@ -146,8 +146,8 @@ public class RemnantFinderTests
 
         // Should find the 80x100 strip on the left
         var left = remnants.FirstOrDefault(r =>
-            r.Width >= 79.9 && r.Width <= 80.1 &&
+            r.Length >= 79.9 && r.Length <= 80.1 &&
-            r.Length >= 99.9);
+            r.Width >= 99.9);
         Assert.NotNull(left);
     }
 
@@ -186,7 +186,7 @@ public class RemnantFinderTests
         var remnants = finder.FindRemnants();
 
         var gap = remnants.FirstOrDefault(r =>
-            r.Width >= 19.9 && r.Width <= 20.1);
+            r.Length >= 19.9 && r.Length <= 20.1);
         Assert.NotNull(gap);
     }
 
@@ -202,7 +202,7 @@ public class RemnantFinderTests
         var remnants = finder.FindRemnants();
 
         var gap = remnants.FirstOrDefault(r =>
-            r.Width >= 19.9 && r.Width <= 20.1);
+            r.Length >= 19.9 && r.Length <= 20.1);
         Assert.NotNull(gap);
     }
 
@@ -280,9 +280,9 @@ public class RemnantFinderTests
         finder.AddObstacle(new Box(0, 47, 21, 6));
         var remnants = finder.FindRemnants();
 
-        var above = remnants.FirstOrDefault(r => r.Bottom >= 53 - 0.1 && r.Width > 50);
+        var above = remnants.FirstOrDefault(r => r.Bottom >= 53 - 0.1 && r.Length > 50);
-        var below = remnants.FirstOrDefault(r => r.Top <= 47 + 0.1 && r.Width > 50);
+        var below = remnants.FirstOrDefault(r => r.Top <= 47 + 0.1 && r.Length > 50);
-        var right = remnants.FirstOrDefault(r => r.Left >= 21 - 0.1 && r.Length > 50);
+        var right = remnants.FirstOrDefault(r => r.Left >= 21 - 0.1 && r.Width > 50);
 
         Assert.NotNull(above);
         Assert.NotNull(below);
@@ -312,10 +312,10 @@ public class RemnantFinderTests
         var topGap = tiered.FirstOrDefault(t =>
             t.Box.Bottom > 50 && t.Box.Bottom < 55 &&
             t.Box.Left < 1 &&
-            t.Box.Width > 100 &&
+            t.Box.Length > 100 &&
-            t.Box.Length > 5);
+            t.Box.Width > 5);
 
-        Assert.True(topGap.Box.Width > 0, "Expected remnant above main grid");
+        Assert.True(topGap.Box.Length > 0, "Expected remnant above main grid");
     }
 
     [Fact]
@@ -361,11 +361,11 @@ public class RemnantFinderTests
 
         // The gap at x < 106 from y=53.14 to y=59.8 should be found.
         Assert.True(remnants.Count > 0, "Should find gap above main grid");
-        var topRemnant = remnants.FirstOrDefault(r => r.Length >= 5.375 && r.Width > 50);
+        var topRemnant = remnants.FirstOrDefault(r => r.Width >= 5.375 && r.Length > 50);
         Assert.NotNull(topRemnant);
 
         // Verify dimensions are close to the expected ~104 x 6.6 gap.
-        Assert.True(topRemnant.Width > 100, $"Expected width > 100, got {topRemnant.Width:F1}");
+        Assert.True(topRemnant.Length > 100, $"Expected length > 100, got {topRemnant.Length:F1}");
-        Assert.True(topRemnant.Length > 6, $"Expected length > 6, got {topRemnant.Length:F1}");
+        Assert.True(topRemnant.Width > 6, $"Expected width > 6, got {topRemnant.Width:F1}");
     }
 }

OpenNest.Tests/Geometry/PolygonHelperTests.cs

@@ -123,7 +123,7 @@ public class PolygonHelperTests
         var rotated = PolygonHelper.RotatePolygon(polygon, Angle.HalfPI);
         rotated.UpdateBounds();
 
-        Assert.True(System.Math.Abs(rotated.BoundingBox.Width - 10) < 0.1);
+        Assert.True(System.Math.Abs(rotated.BoundingBox.Length - 10) < 0.1);
-        Assert.True(System.Math.Abs(rotated.BoundingBox.Length - 20) < 0.1);
+        Assert.True(System.Math.Abs(rotated.BoundingBox.Width - 20) < 0.1);
     }
 }

OpenNest.Tests/Shapes/IsoscelesTriangleShapeTests.cs

@@ -11,8 +11,8 @@ public class IsoscelesTriangleShapeTests
         var drawing = shape.GetDrawing();
 
         var bbox = drawing.Program.BoundingBox();
-        Assert.Equal(10, bbox.Width, 0.01);
+        Assert.Equal(10, bbox.Length, 0.01);
-        Assert.Equal(8, bbox.Length, 0.01);
+        Assert.Equal(8, bbox.Width, 0.01);
     }
 
     [Fact]

OpenNest.Tests/Shapes/LShapeTests.cs

@@ -11,8 +11,8 @@ public class LShapeTests
         var drawing = shape.GetDrawing();
 
         var bbox = drawing.Program.BoundingBox();
-        Assert.Equal(10, bbox.Width, 0.01);
+        Assert.Equal(10, bbox.Length, 0.01);
-        Assert.Equal(20, bbox.Length, 0.01);
+        Assert.Equal(20, bbox.Width, 0.01);
     }
 
     [Fact]

OpenNest.Tests/Shapes/RectangleShapeTests.cs

@@ -11,8 +11,8 @@ public class RectangleShapeTests
         var drawing = shape.GetDrawing();
 
         var bbox = drawing.Program.BoundingBox();
-        Assert.Equal(10, bbox.Width, 0.01);
+        Assert.Equal(10, bbox.Length, 0.01);
-        Assert.Equal(5, bbox.Length, 0.01);
+        Assert.Equal(5, bbox.Width, 0.01);
     }
 
     [Fact]

OpenNest.Tests/Shapes/RightTriangleShapeTests.cs

@@ -11,8 +11,8 @@ public class RightTriangleShapeTests
         var drawing = shape.GetDrawing();
 
         var bbox = drawing.Program.BoundingBox();
-        Assert.Equal(12, bbox.Width, 0.01);
+        Assert.Equal(12, bbox.Length, 0.01);
-        Assert.Equal(8, bbox.Length, 0.01);
+        Assert.Equal(8, bbox.Width, 0.01);
     }
 
     [Fact]

OpenNest.Tests/Shapes/RoundedRectangleShapeTests.cs

@@ -11,8 +11,8 @@ public class RoundedRectangleShapeTests
         var drawing = shape.GetDrawing();
 
         var bbox = drawing.Program.BoundingBox();
-        Assert.Equal(20, bbox.Width, 0.1);
+        Assert.Equal(20, bbox.Length, 0.1);
-        Assert.Equal(10, bbox.Length, 0.1);
+        Assert.Equal(10, bbox.Width, 0.1);
     }
 
     [Fact]

OpenNest.Tests/Shapes/TShapeTests.cs

@@ -11,8 +11,8 @@ public class TShapeTests
         var drawing = shape.GetDrawing();
 
         var bbox = drawing.Program.BoundingBox();
-        Assert.Equal(12, bbox.Width, 0.01);
+        Assert.Equal(12, bbox.Length, 0.01);
-        Assert.Equal(18, bbox.Length, 0.01);
+        Assert.Equal(18, bbox.Width, 0.01);
     }
 
     [Fact]

OpenNest.Tests/Shapes/TrapezoidShapeTests.cs

@@ -11,8 +11,8 @@ public class TrapezoidShapeTests
         var drawing = shape.GetDrawing();
 
         var bbox = drawing.Program.BoundingBox();
-        Assert.Equal(20, bbox.Width, 0.01);
+        Assert.Equal(20, bbox.Length, 0.01);
-        Assert.Equal(8, bbox.Length, 0.01);
+        Assert.Equal(8, bbox.Width, 0.01);
     }
 
     [Fact]

OpenNest.Tests/Splitting/DrawingSplitterTests.cs

@@ -161,11 +161,11 @@ public class DrawingSplitterTests
         var bb2 = results[1].Program.BoundingBox();
 
         // Piece lengths should sum to original length
-        Assert.Equal(100.0, bb1.Width + bb2.Width, 1);
+        Assert.Equal(100.0, bb1.Length + bb2.Length, 1);
 
         // Both pieces should have the same width as the original
-        Assert.Equal(100.0, bb1.Length, 1);
+        Assert.Equal(100.0, bb1.Width, 1);
-        Assert.Equal(100.0, bb2.Length, 1);
+        Assert.Equal(100.0, bb2.Width, 1);
     }
 
     [Fact]
@@ -183,11 +183,11 @@ public class DrawingSplitterTests
         var bb2 = results[1].Program.BoundingBox();
 
         // Piece widths should sum to original width
-        Assert.Equal(100.0, bb1.Length + bb2.Length, 1);
+        Assert.Equal(100.0, bb1.Width + bb2.Width, 1);
 
         // Both pieces should have the same length as the original
-        Assert.Equal(100.0, bb1.Width, 1);
+        Assert.Equal(100.0, bb1.Length, 1);
-        Assert.Equal(100.0, bb2.Width, 1);
+        Assert.Equal(100.0, bb2.Length, 1);
     }
 
     [Fact]
@@ -287,8 +287,8 @@ public class DrawingSplitterTests
         var bb2 = results[1].Program.BoundingBox();
 
         // Left piece should be 30 long, right piece should be 70 long
-        Assert.Equal(30.0, bb1.Width, 1);
+        Assert.Equal(30.0, bb1.Length, 1);
-        Assert.Equal(70.0, bb2.Width, 1);
+        Assert.Equal(70.0, bb2.Length, 1);
     }
 
     [Fact]

OpenNest.Tests/Strategies/StripeFillerTests.cs

@@ -37,8 +37,8 @@ public class StripeFillerTests
         Drawing drawing, double spacing)
     {
         var bb = drawing.Program.BoundingBox();
-        var w = bb.Width;
+        var w = bb.Length;
-        var h = bb.Length;
+        var h = bb.Width;
 
         var candidate = new PairCandidate
         {
@@ -85,7 +85,7 @@ public class StripeFillerTests
             pattern.Parts, 22.0, NestDirection.Horizontal);
 
         var rotated = FillHelpers.BuildRotatedPattern(pattern.Parts, angle);
-        var span = rotated.BoundingBox.Width;
+        var span = rotated.BoundingBox.Length;
         Assert.True(System.Math.Abs(span - 22.0) < 0.5,
             $"Expected span ~22, got {span:F2} at {OpenNest.Math.Angle.ToDegrees(angle):F1}°");
     }

OpenNest/Actions/ActionClone.cs

@@ -198,9 +198,9 @@ namespace OpenNest.Actions
                 Box cutoffBox;
 
                 if (cutoff.Axis == CutOffAxis.Vertical)
-                    cutoffBox = new Box(cutoff.Position.X, plateBounds.Y, 0, plateBounds.Length);
+                    cutoffBox = new Box(cutoff.Position.X, plateBounds.Y, 0, plateBounds.Width);
                 else
-                    cutoffBox = new Box(plateBounds.X, cutoff.Position.Y, plateBounds.Width, 0);
+                    cutoffBox = new Box(plateBounds.X, cutoff.Position.Y, plateBounds.Length, 0);
 
                 boxes.Add(cutoffBox.Offset(plate.PartSpacing));
             }

OpenNest/Actions/ActionSelectArea.cs

@@ -92,8 +92,8 @@ namespace OpenNest.Actions
 
             var location = plateView.PointWorldToGraph(SelectedArea.Location);
             var size = new SizeF(
-                plateView.LengthWorldToGui(SelectedArea.Width),
+                plateView.LengthWorldToGui(SelectedArea.Length),
-                plateView.LengthWorldToGui(SelectedArea.Length));
+                plateView.LengthWorldToGui(SelectedArea.Width));
 
             var rect = new System.Drawing.RectangleF(location.X, location.Y - size.Height, size.Width, size.Height);
 
@@ -176,9 +176,9 @@ namespace OpenNest.Actions
                 Box cutoffBox;
 
                 if (cutoff.Axis == CutOffAxis.Vertical)
-                    cutoffBox = new Box(cutoff.Position.X, plateBounds.Y, 0, plateBounds.Length);
+                    cutoffBox = new Box(cutoff.Position.X, plateBounds.Y, 0, plateBounds.Width);
                 else
-                    cutoffBox = new Box(plateBounds.X, cutoff.Position.Y, plateBounds.Width, 0);
+                    cutoffBox = new Box(plateBounds.X, cutoff.Position.Y, plateBounds.Length, 0);
 
                 boxes.Add(cutoffBox.Offset(plateView.Plate.PartSpacing));
             }

OpenNest/Controls/DrawControl.cs

@@ -206,7 +206,7 @@ namespace OpenNest.Controls
 
         public virtual void ZoomToArea(Box box, bool redraw = true)
         {
-            ZoomToArea(box.X, box.Y, box.Width, box.Length, redraw);
+            ZoomToArea(box.X, box.Y, box.Length, box.Width, redraw);
         }
 
         public virtual void ZoomToArea(double x, double y, double width, double height, bool redraw = true)

OpenNest/Controls/PlateRenderer.cs

@@ -190,8 +190,8 @@ namespace OpenNest.Controls
             var rect = new RectangleF
             {
                 Location = view.PointWorldToGraph(workArea.Location),
-                Width = view.LengthWorldToGui(workArea.Width),
+                Width = view.LengthWorldToGui(workArea.Length),
-                Height = view.LengthWorldToGui(workArea.Length)
+                Height = view.LengthWorldToGui(workArea.Width)
             };
             rect.Y -= rect.Height;
 
@@ -226,8 +226,8 @@ namespace OpenNest.Controls
             {
                 var box = remnants[i];
                 var loc = view.PointWorldToGraph(box.Location);
-                var w = view.LengthWorldToGui(box.Width);
+                var w = view.LengthWorldToGui(box.Length);
-                var h = view.LengthWorldToGui(box.Length);
+                var h = view.LengthWorldToGui(box.Width);
                 var rect = new RectangleF(loc.X, loc.Y - h, w, h);
 
                 var priority = view.DebugRemnantPriorities != null && i < view.DebugRemnantPriorities.Count
@@ -355,7 +355,7 @@ namespace OpenNest.Controls
                     var location = part.Location;
                     var pt1 = view.PointWorldToGraph(location);
                     var pt2 = view.PointWorldToGraph(new Vector(
-                        location.X + box.Width, location.Y + box.Length));
+                        location.X + box.Length, location.Y + box.Width));
                     using var warnPen = new Pen(Color.FromArgb(180, 255, 140, 0), 2f);
                     g.DrawRectangle(warnPen, pt1.X, pt2.Y,
                         System.Math.Abs(pt2.X - pt1.X), System.Math.Abs(pt2.Y - pt1.Y));
@@ -542,8 +542,8 @@ namespace OpenNest.Controls
             var rect = new RectangleF
             {
                 Location = view.PointWorldToGraph(box.Location),
-                Width = view.LengthWorldToGui(box.Width),
+                Width = view.LengthWorldToGui(box.Length),
-                Height = view.LengthWorldToGui(box.Length)
+                Height = view.LengthWorldToGui(box.Width)
             };
 
             g.DrawRectangle(view.ColorScheme.BoundingBoxPen, rect.X, rect.Y - rect.Height, rect.Width, rect.Height);

OpenNest/Forms/EditNestInfoForm.cs

@@ -173,13 +173,13 @@ namespace OpenNest.Forms
                 return;
             }
 
-            if (LeftSpacing + RightSpacing >= size.Width)
+            if (LeftSpacing + RightSpacing >= size.Length)
             {
                 applyButton.Enabled = false;
                 return;
             }
 
-            if (TopSpacing + BottomSpacing >= size.Length)
+            if (TopSpacing + BottomSpacing >= size.Width)
             {
                 applyButton.Enabled = false;
                 return;

OpenNest/Forms/EditPlateForm.cs

@@ -131,13 +131,13 @@ namespace OpenNest.Forms
                 return;
             }
 
-            if (LeftSpacing + RightSpacing >= size.Width)
+            if (LeftSpacing + RightSpacing >= size.Length)
             {
                 applyButton.Enabled = false;
                 return;
             }
 
-            if (TopSpacing + BottomSpacing >= size.Length)
+            if (TopSpacing + BottomSpacing >= size.Width)
             {
                 applyButton.Enabled = false;
                 return;

OpenNest/Forms/OptionsForm.Designer.cs

@@ -42,6 +42,7 @@
             this.saveButton = new System.Windows.Forms.Button();
             this.cancelButton = new System.Windows.Forms.Button();
             this.bottomPanel1 = new OpenNest.Controls.BottomPanel();
+            this.strategyGrid = new System.Windows.Forms.DataGridView();
             this.strategyGroupBox = new System.Windows.Forms.GroupBox();
             ((System.ComponentModel.ISupportInitialize)(this.numericUpDown1)).BeginInit();
             this.tableLayoutPanel1.SuspendLayout();
@@ -212,8 +213,24 @@
             this.bottomPanel1.Size = new System.Drawing.Size(708, 50);
             this.bottomPanel1.TabIndex = 1;
             //
+            // strategyGrid
+            //
+            this.strategyGrid.AllowUserToAddRows = false;
+            this.strategyGrid.AllowUserToDeleteRows = false;
+            this.strategyGrid.AllowUserToResizeRows = false;
+            this.strategyGrid.BackgroundColor = System.Drawing.SystemColors.Window;
+            this.strategyGrid.BorderStyle = System.Windows.Forms.BorderStyle.None;
+            this.strategyGrid.ColumnHeadersHeightSizeMode = System.Windows.Forms.DataGridViewColumnHeadersHeightSizeMode.AutoSize;
+            this.strategyGrid.Dock = System.Windows.Forms.DockStyle.Fill;
+            this.strategyGrid.Location = new System.Drawing.Point(3, 18);
+            this.strategyGrid.Name = "strategyGrid";
+            this.strategyGrid.RowHeadersVisible = false;
+            this.strategyGrid.SelectionMode = System.Windows.Forms.DataGridViewSelectionMode.FullRowSelect;
+            this.strategyGrid.TabIndex = 0;
+            //
             // strategyGroupBox
             //
+            this.strategyGroupBox.Controls.Add(this.strategyGrid);
             this.strategyGroupBox.Location = new System.Drawing.Point(12, 178);
             this.strategyGroupBox.Name = "strategyGroupBox";
             this.strategyGroupBox.Size = new System.Drawing.Size(684, 180);
@@ -263,6 +280,7 @@
         private System.Windows.Forms.TextBox textBox1;
         private System.Windows.Forms.Label label3;
         private System.Windows.Forms.Button button1;
+        private System.Windows.Forms.DataGridView strategyGrid;
         private System.Windows.Forms.GroupBox strategyGroupBox;
     }
 }

OpenNest/Forms/OptionsForm.cs

@@ -1,4 +1,4 @@
-using OpenNest.Engine.Strategies;
+using OpenNest.Engine.Strategies;
 using OpenNest.Properties;
 using System;
 using System.Collections.Generic;
@@ -9,12 +9,10 @@ namespace OpenNest.Forms
 {
     public partial class OptionsForm : Form
     {
-        private readonly List<CheckBox> _strategyCheckBoxes = new();
-
         public OptionsForm()
         {
             InitializeComponent();
-            BuildStrategyCheckBoxes();
+            BuildStrategyGrid();
         }
 
         protected override void OnLoad(EventArgs e)
@@ -23,23 +21,44 @@ namespace OpenNest.Forms
             LoadSettings();
         }
 
-        private void BuildStrategyCheckBoxes()
+        private void BuildStrategyGrid()
         {
-            var strategies = FillStrategyRegistry.AllStrategies;
+            strategyGrid.AutoGenerateColumns = false;
-            var y = 20;
 
-            foreach (var strategy in strategies)
+            strategyGrid.Columns.Add(new DataGridViewCheckBoxColumn
             {
-                var cb = new CheckBox
+                Name = "Enabled",
-                {
+                HeaderText = "",
-                    Text = strategy.Name,
+                Width = 30,
-                    Tag = strategy.Name,
+            });
-                    AutoSize = true,
+
-                    Location = new System.Drawing.Point(10, y),
+            strategyGrid.Columns.Add(new DataGridViewTextBoxColumn
-                };
+            {
-                strategyGroupBox.Controls.Add(cb);
+                Name = "Name",
-                _strategyCheckBoxes.Add(cb);
+                HeaderText = "Strategy",
-                y += 24;
+                ReadOnly = true,
+                AutoSizeMode = DataGridViewAutoSizeColumnMode.Fill,
+            });
+
+            strategyGrid.Columns.Add(new DataGridViewTextBoxColumn
+            {
+                Name = "Phase",
+                HeaderText = "Phase",
+                ReadOnly = true,
+                Width = 100,
+            });
+
+            strategyGrid.Columns.Add(new DataGridViewTextBoxColumn
+            {
+                Name = "Order",
+                HeaderText = "Order",
+                ReadOnly = true,
+                Width = 55,
+            });
+
+            foreach (var strategy in FillStrategyRegistry.AllStrategies)
+            {
+                strategyGrid.Rows.Add(true, strategy.Name, strategy.Phase, strategy.Order);
             }
         }
 
@@ -51,8 +70,8 @@ namespace OpenNest.Forms
             numericUpDown2.Value = (decimal)Settings.Default.ImportSplinePrecision;
 
             var disabledNames = ParseDisabledStrategies(Settings.Default.DisabledStrategies);
-            foreach (var cb in _strategyCheckBoxes)
+            foreach (DataGridViewRow row in strategyGrid.Rows)
-                cb.Checked = !disabledNames.Contains((string)cb.Tag);
+                row.Cells["Enabled"].Value = !disabledNames.Contains((string)row.Cells["Name"].Value);
         }
 
         private void SaveSettings()
@@ -62,9 +81,12 @@ namespace OpenNest.Forms
             Settings.Default.AutoSizePlateFactor = (double)numericUpDown1.Value;
             Settings.Default.ImportSplinePrecision = (int)numericUpDown2.Value;
 
-            var disabledNames = _strategyCheckBoxes
+            var disabledNames = new List<string>();
-                .Where(cb => !cb.Checked)
+            foreach (DataGridViewRow row in strategyGrid.Rows)
-                .Select(cb => (string)cb.Tag);
+            {
+                if (row.Cells["Enabled"].Value is false)
+                    disabledNames.Add((string)row.Cells["Name"].Value);
+            }
             Settings.Default.DisabledStrategies = string.Join(",", disabledNames);
 
             Settings.Default.Save();

OpenNest/Forms/SimplifierViewerForm.cs

@@ -112,8 +112,8 @@ public partial class SimplifierViewerForm : Form
         var padded = new Box(
             candidate.BoundingBox.X - tol * 2,
             candidate.BoundingBox.Y - tol * 2,
-            candidate.BoundingBox.Width + tol * 4,
+            candidate.BoundingBox.Length + tol * 4,
-            candidate.BoundingBox.Length + tol * 4);
+            candidate.BoundingBox.Width + tol * 4);
         entityView.ZoomToArea(padded);
     }
 

OpenNest/Forms/SplitDrawingForm.cs

@@ -78,7 +78,7 @@ public partial class SplitDrawingForm : Form
                 var usable = plateW - 2 * spacing - overhang;
                 if (usable > 0)
                 {
-                    var splits = (int)System.Math.Ceiling(_drawingBounds.Width / usable) - 1;
+                    var splits = (int)System.Math.Ceiling(_drawingBounds.Length / usable) - 1;
                     for (var i = 1; i <= splits; i++)
                         _splitLines.Add(new SplitLine(_drawingBounds.X + usable * i, CutOffAxis.Vertical));
                 }
@@ -88,7 +88,7 @@ public partial class SplitDrawingForm : Form
                 var usable = plateH - 2 * spacing - overhang;
                 if (usable > 0)
                 {
-                    var splits = (int)System.Math.Ceiling(_drawingBounds.Length / usable) - 1;
+                    var splits = (int)System.Math.Ceiling(_drawingBounds.Width / usable) - 1;
                     for (var i = 1; i <= splits; i++)
                         _splitLines.Add(new SplitLine(_drawingBounds.Y + usable * i, CutOffAxis.Horizontal));
                 }

OpenNest/LayoutPart.cs

@@ -128,7 +128,7 @@ namespace OpenNest
             if (shapes.Count == 0)
             {
                 var bbox = BasePart.BaseDrawing.Program.BoundingBox();
-                return new Vector(bbox.Location.X + bbox.Width / 2, bbox.Location.Y + bbox.Length / 2);
+                return new Vector(bbox.Location.X + bbox.Length / 2, bbox.Location.Y + bbox.Width / 2);
             }
 
             var profile = new ShapeProfile(nonRapid);