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fix: prevent GeometryOptimizer from merging semicircular arcs into invalid arc

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After splitting a drawing with a circular hole, CadConverterForm writes
the split piece to DXF and re-imports it. The circle (decomposed into
two semicircular arcs by DrawingSplitter) was being incorrectly merged
back into a single zero-sweep arc by GeometryOptimizer.TryJoinArcs
during reimport.

Root cause: TryJoinArcs mutated input arc angles in-place and didn't
guard against merging two arcs that together form a full circle. When
arc2 had startAngle=π, endAngle=0 (DXF wrap-around from 360°→0°), the
mutation produced startAngle=-π, and the merge created an arc with
startAngle=π, endAngle=π (zero sweep), losing half the hole.

Fix: use local variables instead of mutating inputs, require arcs to be
adjacent (endpoints touching) rather than just overlapping, and refuse
to merge when the combined sweep would be a full circle.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
This commit is contained in:
AJ Isaacs
2026-03-25 20:34:38 -04:00
parent 269746b8a4
commit 19001ea5be
2 changed files with 286 additions and 29 deletions
Download Patch File Download Diff File Expand all files Collapse all files

27
OpenNest.Core/Geometry/GeometryOptimizer.cs
View File

@@ -133,17 +133,30 @@ namespace OpenNest.Geometry
if (!arc1.Radius.IsEqualTo(arc2.Radius))
return false;
if (arc1.StartAngle > arc1.EndAngle)
arc1.StartAngle -= Angle.TwoPI;
var start1 = arc1.StartAngle;
var end1 = arc1.EndAngle;
var start2 = arc2.StartAngle;
var end2 = arc2.EndAngle;
if (arc2.StartAngle > arc2.EndAngle)
arc2.StartAngle -= Angle.TwoPI;
if (start1 > end1)
start1 -= Angle.TwoPI;
if (arc1.EndAngle < arc2.StartAngle || arc1.StartAngle > arc2.EndAngle)
if (start2 > end2)
start2 -= Angle.TwoPI;
// Check that arcs are adjacent (endpoints touch), not overlapping
var touch1 = end1.IsEqualTo(start2) || (end1 + Angle.TwoPI).IsEqualTo(start2);
var touch2 = end2.IsEqualTo(start1) || (end2 + Angle.TwoPI).IsEqualTo(start1);
if (!touch1 && !touch2)
return false;
var startAngle = arc1.StartAngle < arc2.StartAngle ? arc1.StartAngle : arc2.StartAngle;
var endAngle = arc1.EndAngle > arc2.EndAngle ? arc1.EndAngle : arc2.EndAngle;
var startAngle = start1 < start2 ? start1 : start2;
var endAngle = end1 > end2 ? end1 : end2;
// Don't merge if the result would be a full circle (start == end)
var sweep = endAngle - startAngle;
if (sweep >= Angle.TwoPI - Tolerance.Epsilon)
return false;
if (startAngle < 0) startAngle += Angle.TwoPI;
if (endAngle < 0) endAngle += Angle.TwoPI;

288
OpenNest.Tests/Splitting/DrawingSplitterTests.cs
View File

@@ -1,30 +1,15 @@
using OpenNest.Converters;
using OpenNest.Geometry;
using OpenNest.Shapes;
namespace OpenNest.Tests.Splitting;
public class DrawingSplitterTests
{
/// <summary>
/// Helper: creates a Drawing from a rectangular perimeter.
/// </summary>
private static Drawing MakeRectangleDrawing(string name, double width, double height)
{
var entities = new List<Entity>
{
new Line(new Vector(0, 0), new Vector(width, 0)),
new Line(new Vector(width, 0), new Vector(width, height)),
new Line(new Vector(width, height), new Vector(0, height)),
new Line(new Vector(0, height), new Vector(0, 0))
};
var pgm = ConvertGeometry.ToProgram(entities);
return new Drawing(name, pgm);
}
[Fact]
public void Split_Rectangle_Vertical_ProducesTwoPieces()
{
var drawing = MakeRectangleDrawing("RECT", 100, 50);
var drawing = new RectangleShape { Name = "RECT", Length = 100, Width = 50 }.GetDrawing();
var splitLines = new List<SplitLine> { new SplitLine(50.0, CutOffAxis.Vertical) };
var parameters = new SplitParameters { Type = SplitType.Straight };
@@ -42,7 +27,7 @@ public class DrawingSplitterTests
[Fact]
public void Split_Rectangle_Horizontal_ProducesTwoPieces()
{
var drawing = MakeRectangleDrawing("RECT", 100, 60);
var drawing = new RectangleShape { Name = "RECT", Length = 100, Width = 60 }.GetDrawing();
var splitLines = new List<SplitLine> { new SplitLine(30.0, CutOffAxis.Horizontal) };
var parameters = new SplitParameters { Type = SplitType.Straight };
@@ -56,7 +41,7 @@ public class DrawingSplitterTests
[Fact]
public void Split_ThreePieces_NamesSequentially()
{
var drawing = MakeRectangleDrawing("PART", 150, 50);
var drawing = new RectangleShape { Name = "PART", Length = 150, Width = 50 }.GetDrawing();
var splitLines = new List<SplitLine>
{
new SplitLine(50.0, CutOffAxis.Vertical),
@@ -75,7 +60,7 @@ public class DrawingSplitterTests
[Fact]
public void Split_CopiesDrawingProperties()
{
var drawing = MakeRectangleDrawing("PART", 100, 50);
var drawing = new RectangleShape { Name = "PART", Length = 100, Width = 50 }.GetDrawing();
drawing.Color = System.Drawing.Color.Red;
drawing.Priority = 5;
@@ -93,7 +78,7 @@ public class DrawingSplitterTests
[Fact]
public void Split_PiecesNormalizedToOrigin()
{
var drawing = MakeRectangleDrawing("PART", 100, 50);
var drawing = new RectangleShape { Name = "PART", Length = 100, Width = 50 }.GetDrawing();
var results = DrawingSplitter.Split(drawing,
new List<SplitLine> { new SplitLine(50.0, CutOffAxis.Vertical) },
new SplitParameters());
@@ -146,7 +131,7 @@ public class DrawingSplitterTests
[Fact]
public void Split_GridSplit_ProducesFourPieces()
{
var drawing = MakeRectangleDrawing("GRID", 100, 100);
var drawing = new RectangleShape { Name = "GRID", Length = 100, Width = 100 }.GetDrawing();
var splitLines = new List<SplitLine>
{
new SplitLine(50.0, CutOffAxis.Vertical),
@@ -160,4 +145,263 @@ public class DrawingSplitterTests
Assert.Equal("GRID-3", results[2].Name);
Assert.Equal("GRID-4", results[3].Name);
}
[Fact]
public void Split_Square_Vertical_PieceWidthsSumToOriginal()
{
var drawing = new RectangleShape { Name = "SQ", Length = 100, Width = 100 }.GetDrawing();
var splitLines = new List<SplitLine> { new SplitLine(40.0, CutOffAxis.Vertical) };
var parameters = new SplitParameters { Type = SplitType.Straight };
var results = DrawingSplitter.Split(drawing, splitLines, parameters);
Assert.Equal(2, results.Count);
var bb1 = results[0].Program.BoundingBox();
var bb2 = results[1].Program.BoundingBox();
// Piece lengths should sum to original length
Assert.Equal(100.0, bb1.Width + bb2.Width, 1);
// Both pieces should have the same width as the original
Assert.Equal(100.0, bb1.Length, 1);
Assert.Equal(100.0, bb2.Length, 1);
}
[Fact]
public void Split_Square_Horizontal_PieceHeightsSumToOriginal()
{
var drawing = new RectangleShape { Name = "SQ", Length = 100, Width = 100 }.GetDrawing();
var splitLines = new List<SplitLine> { new SplitLine(60.0, CutOffAxis.Horizontal) };
var parameters = new SplitParameters { Type = SplitType.Straight };
var results = DrawingSplitter.Split(drawing, splitLines, parameters);
Assert.Equal(2, results.Count);
var bb1 = results[0].Program.BoundingBox();
var bb2 = results[1].Program.BoundingBox();
// Piece widths should sum to original width
Assert.Equal(100.0, bb1.Length + bb2.Length, 1);
// Both pieces should have the same length as the original
Assert.Equal(100.0, bb1.Width, 1);
Assert.Equal(100.0, bb2.Width, 1);
}
[Fact]
public void Split_Square_Vertical_AreaPreserved()
{
var drawing = new RectangleShape { Name = "SQ", Length = 100, Width = 100 }.GetDrawing();
var originalArea = drawing.Area;
var splitLines = new List<SplitLine> { new SplitLine(50.0, CutOffAxis.Vertical) };
var parameters = new SplitParameters { Type = SplitType.Straight };
var results = DrawingSplitter.Split(drawing, splitLines, parameters);
var totalArea = results.Sum(d => d.Area);
Assert.Equal(originalArea, totalArea, 1);
}
[Fact]
public void Split_Square_Vertical_PiecesAreClosedPerimeters()
{
var drawing = new RectangleShape { Name = "SQ", Length = 100, Width = 100 }.GetDrawing();
var splitLines = new List<SplitLine> { new SplitLine(50.0, CutOffAxis.Vertical) };
var parameters = new SplitParameters { Type = SplitType.Straight };
var results = DrawingSplitter.Split(drawing, splitLines, parameters);
foreach (var piece in results)
{
var entities = ConvertProgram.ToGeometry(piece.Program)
.Where(e => e.Layer != SpecialLayers.Rapid).ToList();
Assert.True(entities.Count >= 4, $"{piece.Name} should have at least 4 entities for a rectangle");
// First entity start should connect to last entity end (closed shape)
var firstStart = GetStartPoint(entities[0]);
var lastEnd = GetEndPoint(entities[^1]);
var closingGap = firstStart.DistanceTo(lastEnd);
Assert.True(closingGap < 0.01,
$"{piece.Name} is not closed: gap of {closingGap:F6} between last end and first start");
// Consecutive entities should connect
for (var i = 0; i < entities.Count - 1; i++)
{
var end = GetEndPoint(entities[i]);
var start = GetStartPoint(entities[i + 1]);
var gap = end.DistanceTo(start);
Assert.True(gap < 0.01,
$"Gap of {gap:F6} between entities {i} and {i + 1} in {piece.Name}");
}
}
}
[Fact]
public void Split_Square_Horizontal_PiecesAreClosedPerimeters()
{
var drawing = new RectangleShape { Name = "SQ", Length = 100, Width = 100 }.GetDrawing();
var splitLines = new List<SplitLine> { new SplitLine(50.0, CutOffAxis.Horizontal) };
var parameters = new SplitParameters { Type = SplitType.Straight };
var results = DrawingSplitter.Split(drawing, splitLines, parameters);
foreach (var piece in results)
{
var entities = ConvertProgram.ToGeometry(piece.Program)
.Where(e => e.Layer != SpecialLayers.Rapid).ToList();
Assert.True(entities.Count >= 4, $"{piece.Name} should have at least 4 entities for a rectangle");
var firstStart = GetStartPoint(entities[0]);
var lastEnd = GetEndPoint(entities[^1]);
var closingGap = firstStart.DistanceTo(lastEnd);
Assert.True(closingGap < 0.01,
$"{piece.Name} is not closed: gap of {closingGap:F6} between last end and first start");
for (var i = 0; i < entities.Count - 1; i++)
{
var end = GetEndPoint(entities[i]);
var start = GetStartPoint(entities[i + 1]);
var gap = end.DistanceTo(start);
Assert.True(gap < 0.01,
$"Gap of {gap:F6} between entities {i} and {i + 1} in {piece.Name}");
}
}
}
[Fact]
public void Split_Square_AsymmetricSplit_PieceDimensionsMatchSplitPosition()
{
var drawing = new RectangleShape { Name = "SQ", Length = 100, Width = 100 }.GetDrawing();
var splitLines = new List<SplitLine> { new SplitLine(30.0, CutOffAxis.Vertical) };
var parameters = new SplitParameters { Type = SplitType.Straight };
var results = DrawingSplitter.Split(drawing, splitLines, parameters);
Assert.Equal(2, results.Count);
var bb1 = results[0].Program.BoundingBox();
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(70.0, bb2.Width, 1);
}
[Fact]
public void Split_CircleHole_NotOnSplitLine_PreservedInCorrectPiece()
{
// Rectangle 100x50 with a circle hole at (20, 25) radius 3
// Split vertically at x=50 — hole is entirely in the left piece
var perimeterEntities = new List<Entity>
{
new Line(new Vector(0, 0), new Vector(100, 0)),
new Line(new Vector(100, 0), new Vector(100, 50)),
new Line(new Vector(100, 50), new Vector(0, 50)),
new Line(new Vector(0, 50), new Vector(0, 0))
};
var hole = new Circle(new Vector(20, 25), 3);
var allEntities = new List<Entity>();
allEntities.AddRange(perimeterEntities);
allEntities.Add(hole);
var pgm = ConvertGeometry.ToProgram(allEntities);
var drawing = new Drawing("CIRC", pgm);
var results = DrawingSplitter.Split(drawing,
new List<SplitLine> { new SplitLine(50.0, CutOffAxis.Vertical) },
new SplitParameters());
Assert.Equal(2, results.Count);
// Left piece should have the hole — verify by checking it has arc entities
var leftEntities = ConvertProgram.ToGeometry(results[0].Program)
.Where(e => e.Layer != SpecialLayers.Rapid).ToList();
var leftArcs = leftEntities.OfType<Arc>().ToList();
// Decomposed circle = 2 arcs. Both should be present.
Assert.True(leftArcs.Count >= 2,
$"Left piece should have at least 2 arcs (full circle), but has {leftArcs.Count}");
// Right piece should have no arcs (hole is on the left)
var rightEntities = ConvertProgram.ToGeometry(results[1].Program)
.Where(e => e.Layer != SpecialLayers.Rapid).ToList();
var rightArcs = rightEntities.OfType<Arc>().ToList();
Assert.Equal(0, rightArcs.Count);
}
[Fact]
public void Split_DxfRoundTrip_CircleHolePreserved()
{
// Two semicircular arcs (decomposed circle) must survive DXF write→reimport.
// Regression: GeometryOptimizer.TryJoinArcs merged them into a single arc
// because it incorrectly handled the wrap-around case (π→2π written as π→0°).
var perimeterEntities = new List<Entity>
{
new Line(new Vector(0, 0), new Vector(100, 0)),
new Line(new Vector(100, 0), new Vector(100, 50)),
new Line(new Vector(100, 50), new Vector(0, 50)),
new Line(new Vector(0, 50), new Vector(0, 0))
};
var hole = new Circle(new Vector(20, 25), 3);
var allEntities = new List<Entity>();
allEntities.AddRange(perimeterEntities);
allEntities.Add(hole);
var pgm = ConvertGeometry.ToProgram(allEntities);
var drawing = new Drawing("CIRC", pgm);
drawing.Bends = new List<OpenNest.Bending.Bend>();
// Split — the circle gets decomposed into two arcs
var results = DrawingSplitter.Split(drawing,
new List<SplitLine> { new SplitLine(50.0, CutOffAxis.Vertical) },
new SplitParameters());
Assert.Equal(2, results.Count);
// Write left piece to DXF and re-import
var tempPath = System.IO.Path.Combine(System.IO.Path.GetTempPath(), "split_roundtrip_test.dxf");
try
{
var writer = new OpenNest.IO.SplitDxfWriter();
writer.Write(tempPath, results[0]);
var reimporter = new OpenNest.IO.DxfImporter();
var reimportResult = reimporter.Import(tempPath);
var afterArcs = reimportResult.Entities.OfType<Arc>().Count();
var afterCircles = reimportResult.Entities.OfType<Circle>().Count();
Assert.True(afterArcs + afterCircles * 2 >= 2,
$"After DXF round-trip: {afterArcs} arcs, {afterCircles} circles (expected 2+ for full hole)");
}
finally
{
if (System.IO.File.Exists(tempPath))
System.IO.File.Delete(tempPath);
}
}
private static Vector GetStartPoint(Entity entity)
{
return entity switch
{
Line l => l.StartPoint,
Arc a => a.StartPoint(),
_ => new Vector(0, 0)
};
}
private static Vector GetEndPoint(Entity entity)
{
return entity switch
{
Line l => l.EndPoint,
Arc a => a.EndPoint(),
_ => new Vector(0, 0)
};
}
}