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refactor(geometry): move polygon offset callers onto ClipperBridge

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Per-entity offsetting left spikes and inverted loops wherever a feature is
narrower than the spacing (1.nest), and RemoveSelfIntersections only
caught proper crossings. The callers that already flatten to polygons now
take a single Clipper region offset instead:

- PolygonHelper (BestFit) and PartBoundary use the conservative mode, which
  keeps their never-under-estimate guarantee. PartBoundary also keeps holes
  that appear when a perimeter curls back on itself.
- NestValidator offsets perimeter and cutouts in one region; Clipper drops
  collapsed cutouts, so the collapsed-or-flipped heuristic goes away.
- CutOff.IntersectPerimeter offsets through the bridge. The old
  OffsetEntity(Left) grew CW perimeters but shrank CCW ones, so with the
  plate's perimeter cache a cut-off ran through the part; slots narrower
  than twice the clearance now close up instead of leaving a gap.
- GetOffsetPartLines (3 overloads) and the AddOffset* helpers had no
  callers and are removed, as is EntityView's never-defined DRAW_OFFSET
  block.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
This commit is contained in:
aj
2026-09-23 09:21:48 -04:00
co-authored by Claude Opus 5.5
parent 12f97474b7
commit 9b9386b029
8 changed files with 180 additions and 254 deletions
Download Patch File Download Diff File Expand all files Collapse all files
OpenNest.Benchmark/NestValidator.cs
+27 -46
View File
@@ -315,6 +315,8 @@ namespace OpenNest.Benchmark
? requirement.Name
: part.BaseDrawing.Name;
private const double OutlineTolerance = 0.01;
private sealed class PartOutline
{
public Polygon Perimeter { get; init; }
@@ -324,9 +326,12 @@ namespace OpenNest.Benchmark
/// <summary>
/// Extracts a part's material as world-space polygons - the perimeter and
/// its cutouts - grown by <paramref name="inflateBy"/> (perimeter offset
/// outward, cutouts offset inward). A cutout that closes up under the
/// offset is dropped, which treats it as solid: conservative, since it
/// has no room for another part at the required spacing anyway.
/// outward, cutouts offset inward, in one Clipper region offset). A cutout
/// that closes up under the offset is dropped, which treats it as solid:
/// conservative, since it has no room for another part at the required
/// spacing anyway. The flattening is conservative too (perimeter arcs
/// circumscribed, cutout arcs inscribed), so the check never passes a
/// layout that is closer than the spacing.
/// part.Program is already rotated; only a Location offset is needed.
/// </summary>
private static PartOutline Outline(Part part, double inflateBy)
@@ -344,57 +349,33 @@ namespace OpenNest.Benchmark
if (profile.Perimeter == null)
return null;
var perimeter = profile.Perimeter;
if (inflateBy > Tolerance.Epsilon)
perimeter = perimeter.OffsetOutward(inflateBy) ?? perimeter;
var polygon = ToWorldPolygon(perimeter, part.Location);
if (polygon == null)
return null;
var holes = new List<Polygon>();
foreach (var cutout in profile.Cutouts)
{
var hole = cutout;
if (inflateBy > Tolerance.Epsilon)
{
hole = cutout.OffsetInward(inflateBy);
// An offset that collapsed or flipped inside-out leaves no usable room.
if (
hole == null
|| hole.Area() <= Tolerance.Epsilon
|| hole.Area() >= cutout.Area()
)
continue;
}
var holePolygon = ToWorldPolygon(hole, part.Location);
if (holePolygon != null)
holes.Add(holePolygon);
}
return new PartOutline { Perimeter = polygon, Holes = holes };
}
private static Polygon ToWorldPolygon(Shape shape, Vector location)
{
// Adaptive tolerance instead of Shape.ToPolygon()'s default (up to 1000
// segments per arc) - arc-heavy real parts otherwise produce thousands
// of vertices, which is needlessly slow for a spacing check.
var polygon = shape.ToPolygonWithTolerance(0.01, circumscribe: true);
var region = ClipperBridge.Offset(
profile,
inflateBy > Tolerance.Epsilon ? inflateBy : 0,
OutlineTolerance,
circumscribe: true
);
if (polygon == null)
var perimeter = region.LargestOuter();
if (perimeter == null)
return null;
ToWorld(perimeter, part.Location);
foreach (var hole in region.Holes)
ToWorld(hole, part.Location);
return new PartOutline { Perimeter = perimeter, Holes = region.Holes };
}
private static void ToWorld(Polygon polygon, Vector location)
{
polygon.Offset(location);
polygon.UpdateBounds();
return polygon;
}
}
}
OpenNest.Core/CutOff.cs
+39 -12
View File
@@ -13,6 +13,8 @@ namespace OpenNest
public class CutOff
{
private const double OffsetTolerance = 0.001;
public Vector Position { get; set; }
public CutOffAxis Axis { get; set; }
public double? StartLimit { get; set; }
@@ -163,14 +165,23 @@ namespace OpenNest
double clearance
)
{
var target = OffsetOutward(perimeter, clearance) ?? perimeter;
var usedOffset = target != perimeter;
var offset = OffsetOutward(perimeter, clearance);
var usedOffset = offset != null;
var targets = offset ?? new List<Entity> { perimeter };
var cutLine = new Line(
MakePoint(cutPosition, lineStart),
MakePoint(cutPosition, lineEnd)
);
if (!target.Intersects(cutLine, out var pts) || pts.Count < 2)
var pts = new List<Vector>();
foreach (var target in targets)
{
if (target.Intersects(cutLine, out var targetPts))
pts.AddRange(targetPts);
}
if (pts.Count < 2)
return null;
var coords = pts.Select(pt => Axis == CutOffAxis.Vertical ? pt.Y : pt.X)
@@ -188,21 +199,37 @@ namespace OpenNest
return result;
}
private static Entity OffsetOutward(Entity perimeter, double clearance)
/// <summary>
/// Grows the perimeter by the clearance as one Clipper region offset, so slots
/// narrower than twice the clearance close up instead of leaving a gap the cut
/// could run into. Holes appear only where the perimeter curls back on itself.
/// </summary>
private static List<Entity> OffsetOutward(Entity perimeter, double clearance)
{
if (clearance <= 0)
return null;
try
{
var offset = perimeter.OffsetEntity(clearance, OffsetSide.Left);
offset?.UpdateBounds();
return offset;
}
catch
var offset = perimeter switch
{
Shape shape => ClipperBridge.OffsetPerimeter(
shape,
clearance,
OffsetTolerance,
circumscribe: true
),
Polygon polygon => ClipperBridge.OffsetPerimeter(
polygon,
clearance,
OffsetTolerance,
circumscribe: true
),
_ => null,
};
if (offset == null || offset.Outers.Count == 0)
return null;
}
return offset.Outers.Concat(offset.Holes).Cast<Entity>().ToList();
}
private Vector MakePoint(double cutCoord, double lineCoord) =>
OpenNest.Core/Geometry/ClipperBridge.cs
+52 -9
View File
@@ -18,6 +18,8 @@ namespace OpenNest.Geometry
private const double MiterLimit = 2.0;
private const double ConservativeJoinFactor = 0.25;
/// <summary>
/// Converts a polygon to a Clipper path, dropping the closing vertex and
/// orienting it positive (CCW) or negative (CW).
@@ -90,9 +92,9 @@ namespace OpenNest.Geometry
/// no more than <paramref name="tolerance"/> from the true arc.
/// </summary>
/// <param name="circumscribe">
/// When true, the result never under-estimates the offset: arcs are flattened
/// outside the true curve and the inflation is padded by the chord tolerance
/// and Clipper's rounding.
/// When true, the result never under-estimates the offset: perimeter arcs are
/// flattened outside the true curve, cutout arcs inside it, and the inflation is
/// padded by the round-join chord error and Clipper's rounding.
/// </param>
public static OffsetRegion Offset(
ShapeProfile profile,
@@ -105,8 +107,39 @@ namespace OpenNest.Geometry
return Offset(region, distance, tolerance, circumscribe);
}
/// <summary>
/// Offsets a single closed shape outward, ignoring any cutouts. A perimeter that
/// curls back on itself (a C shape with a narrow mouth) can gain holes.
/// </summary>
public static OffsetRegion OffsetPerimeter(
Shape perimeter,
double distance,
double tolerance,
bool circumscribe = false
)
{
var polygon = perimeter.ToPolygonWithTolerance(tolerance, circumscribe);
return OffsetPerimeter(polygon, distance, tolerance, circumscribe);
}
/// <summary>
/// Offsets a closed polygon outward, whatever its winding.
/// </summary>
public static OffsetRegion OffsetPerimeter(
Polygon perimeter,
double distance,
double tolerance,
bool circumscribe = false
)
{
var region = new PathsD(1);
AddPolygon(region, perimeter, positive: true);
return Offset(region, distance, tolerance, circumscribe);
}
/// <summary>
/// Offsets an already-flattened region (outers positive, holes negative).
/// A distance of zero only unions the region, with no conservative padding.
/// </summary>
public static OffsetRegion Offset(
PathsD region,
@@ -115,13 +148,20 @@ namespace OpenNest.Geometry
bool circumscribe = false
)
{
// Round joins put their vertices on the true arc, so each chord sits inside
// it by up to the join tolerance. In conservative mode, joins use a finer
// tolerance and the inflation is padded by it (plus Clipper's rounding).
var delta = distance;
var joinTolerance = tolerance;
if (circumscribe)
delta += tolerance + 0.5 * System.Math.Pow(10, -Precision);
if (circumscribe && distance > 0)
{
joinTolerance = tolerance * ConservativeJoinFactor;
delta += joinTolerance + 0.5 * System.Math.Pow(10, -Precision);
}
var inflated =
delta == 0
delta <= 0
? Union(region)
: Clipper.InflatePaths(
region,
@@ -130,7 +170,7 @@ namespace OpenNest.Geometry
EndType.Polygon,
MiterLimit,
Precision,
tolerance
joinTolerance
);
var result = new OffsetRegion(new List<Polygon>(), new List<Polygon>());
@@ -167,9 +207,12 @@ namespace OpenNest.Geometry
bool positive
)
{
var polygon = shape.ToPolygonWithTolerance(tolerance, circumscribe);
AddPolygon(region, shape.ToPolygonWithTolerance(tolerance, circumscribe), positive);
}
if (polygon.Vertices.Count < 4)
private static void AddPolygon(PathsD region, Polygon polygon, bool positive)
{
if (polygon.Vertices.Count < 3)
return;
var path = ToPath(polygon, positive);
OpenNest.Core/PartGeometry.cs
+1 -154
View File
@@ -49,7 +49,7 @@ namespace OpenNest
/// <summary>
/// Returns the perimeter entities (Line, Arc, Circle) with spacing offset applied,
/// without tessellation. Much faster than GetOffsetPartLines for parts with many arcs.
/// without tessellation, which keeps arc-heavy parts fast in directional-distance loops.
/// </summary>
public static List<Entity> GetOffsetPerimeterEntities(Part part, double spacing)
{
@@ -149,75 +149,6 @@ namespace OpenNest
return result;
}
public static List<Line> GetOffsetPartLines(
Part part,
double spacing,
double chordTolerance = 0.001,
bool perimeterOnly = false
)
{
var entities = ConvertProgram.ToGeometry(part.Program);
var profile = new ShapeProfile(
entities.Where(e => e.Layer != SpecialLayers.Rapid).ToList()
);
var lines = new List<Line>();
var totalSpacing = spacing;
AddOffsetLines(
lines,
profile.Perimeter.OffsetOutward(totalSpacing),
chordTolerance,
part.Location
);
if (!perimeterOnly)
{
foreach (var cutout in profile.Cutouts)
AddOffsetLines(
lines,
cutout.OffsetInward(totalSpacing),
chordTolerance,
part.Location
);
}
return lines;
}
public static List<Line> GetOffsetPartLines(
Part part,
double spacing,
PushDirection facingDirection,
double chordTolerance = 0.001
)
{
var entities = ConvertProgram.ToGeometry(part.Program);
var profile = new ShapeProfile(
entities.Where(e => e.Layer != SpecialLayers.Rapid).ToList()
);
var lines = new List<Line>();
var totalSpacing = spacing;
AddOffsetDirectionalLines(
lines,
profile.Perimeter.OffsetOutward(totalSpacing),
chordTolerance,
part.Location,
facingDirection
);
foreach (var cutout in profile.Cutouts)
AddOffsetDirectionalLines(
lines,
cutout.OffsetInward(totalSpacing),
chordTolerance,
part.Location,
facingDirection
);
return lines;
}
public static List<Line> GetPartLines(
Part part,
Vector facingDirection,
@@ -240,40 +171,6 @@ namespace OpenNest
return lines;
}
public static List<Line> GetOffsetPartLines(
Part part,
double spacing,
Vector facingDirection,
double chordTolerance = 0.001
)
{
var entities = ConvertProgram.ToGeometry(part.Program);
var profile = new ShapeProfile(
entities.Where(e => e.Layer != SpecialLayers.Rapid).ToList()
);
var lines = new List<Line>();
var totalSpacing = spacing;
AddOffsetDirectionalLines(
lines,
profile.Perimeter.OffsetOutward(totalSpacing),
chordTolerance,
part.Location,
facingDirection
);
foreach (var cutout in profile.Cutouts)
AddOffsetDirectionalLines(
lines,
cutout.OffsetInward(totalSpacing),
chordTolerance,
part.Location,
facingDirection
);
return lines;
}
/// <summary>
/// Returns only polygon edges whose outward normal faces the specified direction vector.
/// </summary>
@@ -353,55 +250,5 @@ namespace OpenNest
return lines;
}
private static void AddOffsetLines(
List<Line> lines,
Shape offsetEntity,
double chordTolerance,
Vector location
)
{
if (offsetEntity == null)
return;
var polygon = offsetEntity.ToPolygonWithTolerance(chordTolerance);
polygon.RemoveSelfIntersections();
polygon.Offset(location);
lines.AddRange(polygon.ToLines());
}
private static void AddOffsetDirectionalLines(
List<Line> lines,
Shape offsetEntity,
double chordTolerance,
Vector location,
PushDirection facingDirection
)
{
if (offsetEntity == null)
return;
var polygon = offsetEntity.ToPolygonWithTolerance(chordTolerance);
polygon.RemoveSelfIntersections();
polygon.Offset(location);
lines.AddRange(GetDirectionalLines(polygon, facingDirection));
}
private static void AddOffsetDirectionalLines(
List<Line> lines,
Shape offsetEntity,
double chordTolerance,
Vector location,
Vector facingDirection
)
{
if (offsetEntity == null)
return;
var polygon = offsetEntity.ToPolygonWithTolerance(chordTolerance);
polygon.RemoveSelfIntersections();
polygon.Offset(location);
lines.AddRange(GetDirectionalLines(polygon, facingDirection));
}
}
}
OpenNest.Engine/BestFit/PolygonHelper.cs
+8 -9
View File
@@ -26,16 +26,15 @@ namespace OpenNest.Engine.BestFit
if (perimeter == null)
return new PolygonExtractionResult(null, Vector.Zero);
// Ensure CW winding for correct outward offset direction.
definedShape.NormalizeWinding();
// Circumscribe so the polygon never under-estimates the part (or its offset).
var polygon =
halfSpacing > 0
? ClipperBridge
.OffsetPerimeter(perimeter, halfSpacing, 0.01, circumscribe: true)
.LargestOuter()
: perimeter.ToPolygonWithTolerance(0.01, circumscribe: true);
var inflated =
halfSpacing > 0 ? (perimeter.OffsetOutward(halfSpacing) ?? perimeter) : perimeter;
// Convert to polygon with circumscribed arcs for tight nesting.
var polygon = inflated.ToPolygonWithTolerance(0.01, circumscribe: true);
if (polygon.Vertices.Count < 3)
if (polygon == null || polygon.Vertices.Count < 3)
return new PolygonExtractionResult(null, Vector.Zero);
// Normalize: move polygon to origin.
OpenNest.Engine/Fill/PartBoundary.cs
+10 -13
View File
@@ -34,19 +34,16 @@ namespace OpenNest.Engine.Fill
if (perimeter != null)
{
var offsetEntity = perimeter.OffsetOutward(spacing);
if (offsetEntity != null)
{
// Circumscribe arcs so polygon vertices are always outside
// the true arc — guarantees the boundary never under-estimates.
var polygon = offsetEntity.ToPolygonWithTolerance(
PolygonTolerance,
circumscribe: true
);
polygon.RemoveSelfIntersections();
_polygons.Add(polygon);
}
// Conservative offset: the boundary never under-estimates the spacing.
// Holes appear only where the perimeter curls back on itself.
var offset = ClipperBridge.OffsetPerimeter(
perimeter,
spacing,
PolygonTolerance,
circumscribe: true
);
_polygons.AddRange(offset.Outers);
_polygons.AddRange(offset.Holes);
}
PrecomputeDirectionalEdges(
OpenNest.Tests/CutOffs/CutOffTests.cs
+43
View File
@@ -121,6 +121,49 @@ public class CutOffTests
Assert.Equal(4, codes.Count);
}
[Theory]
[InlineData(0.3, 19.0)] // Narrower than twice the clearance: the slot closes up.
[InlineData(4.0, 24.0)] // Wide slot: the cut runs in to 1 short of the slot's end.
public void CutOff_UpASlot_KeepsClearanceFromPart(double slotWidth, double firstEnd)
{
// 10x10 part at (20,20) with a 5-deep slot up from the bottom edge, centered
// on the cut line.
var h = slotWidth / 2;
var pgm = new Program();
pgm.Codes.Add(new RapidMove(new Vector(0, 0)));
pgm.Codes.Add(new LinearMove(new Vector(5 - h, 0)));
pgm.Codes.Add(new LinearMove(new Vector(5 - h, 5)));
pgm.Codes.Add(new LinearMove(new Vector(5 + h, 5)));
pgm.Codes.Add(new LinearMove(new Vector(5 + h, 0)));
pgm.Codes.Add(new LinearMove(new Vector(10, 0)));
pgm.Codes.Add(new LinearMove(new Vector(10, 10)));
pgm.Codes.Add(new LinearMove(new Vector(0, 10)));
pgm.Codes.Add(new LinearMove(new Vector(0, 0)));
var plate = new Plate(50, 50);
var part = Part.CreateAtOrigin(new Drawing("slot", pgm));
part.Location = new Vector(20, 20);
plate.Parts.Add(part);
var settings = new CutOffSettings { PartClearance = 1.0 };
var cutoff = new CutOff(new Vector(25, 10), CutOffAxis.Vertical);
cutoff.Regenerate(plate, settings, Plate.BuildPerimeterCache(plate));
var ys = cutoff
.Drawing.Program.Codes.OfType<Motion>()
.Select(m => m.EndPoint.Y)
.OrderBy(y => y)
.ToList();
Assert.Equal(4, ys.Count);
Assert.Equal(0, ys[0], 6);
// A closed slot leaves a shallow dent at its mouth: the cut stops 1 from the
// mouth corners, at 20 - sqrt(1 - 0.15^2) = 19.011.
Assert.InRange(ys[1], firstEnd - 0.02, firstEnd + 0.02);
Assert.InRange(ys[2], 30.999, 31.02);
Assert.Equal(50, ys[3], 6);
}
[Fact]
public void CutOff_ShortSegment_FilteredByMinLength()
{
OpenNest/Controls/EntityView.cs
-11
View File
@@ -165,17 +165,6 @@ namespace OpenNest.Controls
DrawArc(e.Graphics, SimplifierPreview, previewPen);
}
#if DRAW_OFFSET
var offsetShape = new Shape();
offsetShape.Entities.AddRange(Entities);
foreach (
var entity in ((Shape)offsetShape.OffsetEntity(0.25, OffsetSide.Left)).Entities
)
DrawEntity(e.Graphics, entity, Pens.RoyalBlue);
#endif
PaintOverlay?.Invoke(e.Graphics);
}