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fix: orient pair short side along primary axis before convergence

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The convergence loop now ensures the pair starts with its short side
parallel to the primary axis, maximizing the number of pairs that fit.
Also adds ConvergeStripeAngleShrink to try N+1 narrower pairs, and
evaluates both expand and shrink results to pick the better grid.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
This commit is contained in:
AJ Isaacs
2026-03-21 09:22:13 -04:00
parent 811d23510e
commit 3f3d95a5e4
2 changed files with 166 additions and 37 deletions
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198
OpenNest.Engine/Fill/StripeFiller.cs
View File

@@ -49,41 +49,31 @@ public class StripeFiller
var candidate = bestFits[i];
var pairParts = candidate.BuildParts(drawing);
var (angle, waste, count) = ConvergeStripeAngle(
// Try both expand (N wider pairs) and shrink (N+1 narrower pairs)
var expandResult = ConvergeStripeAngle(
pairParts, sheetSpan, spacing, _primaryAxis, _context.Token);
var shrinkResult = ConvergeStripeAngleShrink(
pairParts, sheetSpan, spacing, _primaryAxis, _context.Token);
if (count <= 0)
continue;
var rotatedPattern = FillHelpers.BuildRotatedPattern(pairParts, angle);
var perpDim = GetDimension(rotatedPattern.BoundingBox, perpAxis);
var stripeBox = MakeStripeBox(workArea, perpDim, _primaryAxis);
var stripeEngine = new FillLinear(stripeBox, spacing);
var stripeParts = stripeEngine.Fill(rotatedPattern, _primaryAxis);
if (stripeParts == null || stripeParts.Count == 0)
continue;
var stripePattern = new Pattern();
stripePattern.Parts.AddRange(stripeParts);
stripePattern.UpdateBounds();
var gridEngine = new FillLinear(workArea, spacing);
var gridParts = gridEngine.Fill(stripePattern, perpAxis);
if (gridParts == null || gridParts.Count == 0)
continue;
var allParts = new List<Part>(gridParts);
var remnantParts = FillRemnant(gridParts, drawing, angle, workArea, spacing);
if (remnantParts != null)
allParts.AddRange(remnantParts);
var score = FillScore.Compute(allParts, workArea);
if (bestParts == null || score > bestScore)
// Evaluate both convergence results
foreach (var (angle, waste, count) in new[] { expandResult, shrinkResult })
{
bestParts = allParts;
bestScore = score;
if (count <= 0)
continue;
var result = BuildGrid(pairParts, angle, workArea, spacing, perpAxis, drawing);
if (result == null || result.Count == 0)
continue;
var score = FillScore.Compute(result, workArea);
Debug.WriteLine($"[StripeFiller] {strategyName} candidate {i}: angle={Angle.ToDegrees(angle):F1}°, " +
$"pairsAcross={count}, waste={waste:F2}, grid={result.Count} parts");
if (bestParts == null || score > bestScore)
{
bestParts = result;
bestScore = score;
}
}
NestEngineBase.ReportProgress(_context.Progress, NestPhase.Custom,
@@ -94,6 +84,44 @@ public class StripeFiller
return bestParts ?? new List<Part>();
}
private List<Part> BuildGrid(List<Part> pairParts, double angle,
Box workArea, double spacing, NestDirection perpAxis, Drawing drawing)
{
var rotatedPattern = FillHelpers.BuildRotatedPattern(pairParts, angle);
var perpDim = GetDimension(rotatedPattern.BoundingBox, perpAxis);
var stripeBox = MakeStripeBox(workArea, perpDim, _primaryAxis);
var stripeEngine = new FillLinear(stripeBox, spacing);
var stripeParts = stripeEngine.Fill(rotatedPattern, _primaryAxis);
if (stripeParts == null || stripeParts.Count == 0)
return null;
Debug.WriteLine($"[StripeFiller] Stripe: {stripeParts.Count} parts, " +
$"box={stripeBox.Width:F2}x{stripeBox.Length:F2}");
var stripePattern = new Pattern();
stripePattern.Parts.AddRange(stripeParts);
stripePattern.UpdateBounds();
var gridEngine = new FillLinear(workArea, spacing);
var gridParts = gridEngine.Fill(stripePattern, perpAxis);
if (gridParts == null || gridParts.Count == 0)
return null;
Debug.WriteLine($"[StripeFiller] Grid: {gridParts.Count} parts");
var allParts = new List<Part>(gridParts);
var remnantParts = FillRemnant(gridParts, drawing, angle, workArea, spacing);
if (remnantParts != null)
{
Debug.WriteLine($"[StripeFiller] Remnant: {remnantParts.Count} parts");
allParts.AddRange(remnantParts);
}
return allParts;
}
private List<BestFitResult> GetPairCandidates()
{
List<BestFitResult> bestFits;
@@ -200,18 +228,36 @@ public class StripeFiller
return bestAngle;
}
/// <summary>
/// Returns the rotation angle that orients the pair with its short side
/// along the given axis. Returns 0 if already oriented, PI/2 if rotated.
/// </summary>
private static double OrientShortSideAlong(List<Part> patternParts, NestDirection axis)
{
var box = FillHelpers.BuildRotatedPattern(patternParts, 0).BoundingBox;
var span0 = GetDimension(box, axis);
var perpSpan0 = axis == NestDirection.Horizontal ? box.Length : box.Width;
// Short side already along axis
if (span0 <= perpSpan0)
return 0;
// Rotate 90° to put short side along axis
return Angle.HalfPI;
}
/// <summary>
/// Iteratively finds the rotation angle where N copies of the pattern
/// span the given dimension with minimal waste.
/// span the given dimension with minimal waste by expanding pair width.
/// Returns (angle, waste, pairCount).
/// </summary>
public static (double Angle, double Waste, int Count) ConvergeStripeAngle(
List<Part> patternParts, double sheetSpan, double spacing,
NestDirection axis, CancellationToken token = default)
{
var currentAngle = 0.0;
var currentAngle = OrientShortSideAlong(patternParts, axis);
var bestWaste = double.MaxValue;
var bestAngle = 0.0;
var bestAngle = currentAngle;
var bestCount = 0;
var tolerance = sheetSpan * 0.001;
@@ -251,6 +297,88 @@ public class StripeFiller
return (bestAngle, bestWaste, bestCount);
}
/// <summary>
/// Tries fitting N+1 narrower pairs by shrinking the pair width.
/// Complements ConvergeStripeAngle which only expands.
/// </summary>
public static (double Angle, double Waste, int Count) ConvergeStripeAngleShrink(
List<Part> patternParts, double sheetSpan, double spacing,
NestDirection axis, CancellationToken token = default)
{
// Orient short side along axis before computing N
var baseAngle = OrientShortSideAlong(patternParts, axis);
var naturalPattern = FillHelpers.BuildRotatedPattern(patternParts, baseAngle);
var naturalSpan = GetDimension(naturalPattern.BoundingBox, axis);
if (naturalSpan + spacing <= 0)
return (0, double.MaxValue, 0);
var naturalN = (int)System.Math.Floor((sheetSpan + spacing) / (naturalSpan + spacing));
var targetN = naturalN + 1;
// Target span for N+1 pairs
var targetSpan = (sheetSpan + spacing) / targetN - spacing;
if (targetSpan <= 0)
return (0, double.MaxValue, 0);
// Find the angle that shrinks the pair to targetSpan
var angle = FindAngleForTargetSpan(patternParts, targetSpan, axis);
// Verify the actual span at this angle
var rotated = FillHelpers.BuildRotatedPattern(patternParts, angle);
var actualSpan = GetDimension(rotated.BoundingBox, axis);
var actualN = (int)System.Math.Floor((sheetSpan + spacing) / (actualSpan + spacing));
if (actualN <= 0)
return (0, double.MaxValue, 0);
var usedSpan = actualN * (actualSpan + spacing) - spacing;
var waste = sheetSpan - usedSpan;
// Now converge from this starting point
var bestWaste = waste;
var bestAngle = angle;
var bestCount = actualN;
var tolerance = sheetSpan * 0.001;
var currentAngle = angle;
for (var iteration = 0; iteration < MaxConvergenceIterations; iteration++)
{
token.ThrowIfCancellationRequested();
if (bestWaste <= tolerance)
break;
rotated = FillHelpers.BuildRotatedPattern(patternParts, currentAngle);
var pairSpan = GetDimension(rotated.BoundingBox, axis);
var n = (int)System.Math.Floor((sheetSpan + spacing) / (pairSpan + spacing));
if (n <= 0)
break;
usedSpan = n * (pairSpan + spacing) - spacing;
var remaining = sheetSpan - usedSpan;
if (remaining < bestWaste)
{
bestWaste = remaining;
bestAngle = currentAngle;
bestCount = n;
}
if (remaining <= tolerance)
break;
var delta = remaining / n;
var newTarget = pairSpan + delta;
currentAngle = FindAngleForTargetSpan(patternParts, newTarget, axis);
}
return (bestAngle, bestWaste, bestCount);
}
private static double BisectForTarget(
List<Part> patternParts, double lo, double hi,
double targetSpan, NestDirection axis)

5
OpenNest.Tests/Strategies/StripeFillerTests.cs
View File

@@ -114,12 +114,13 @@ public class StripeFillerTests
[Fact]
public void ConvergeStripeAngle_HandlesExactFit()
{
// 10x5 pattern: short side (5) oriented along axis, so more pairs fit
var pattern = MakeRectPattern(10, 5);
var (angle, waste, count) = StripeFiller.ConvergeStripeAngle(
pattern.Parts, 100.0, 0.0, NestDirection.Horizontal);
Assert.Equal(10, count);
Assert.True(waste < 0.2, $"Expected near-zero waste, got {waste:F2}");
Assert.True(count >= 10, $"Expected at least 10 pairs, got {count}");
Assert.True(waste < 1.0, $"Expected low waste, got {waste:F2}");
}
[Fact]