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feat: add EllipseConverter arc fitting with normal-constrained G1 continuity

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Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
This commit is contained in:
AJ Isaacs
2026-03-27 15:01:55 -04:00
parent c40941ed35
commit 4a5ed1b9c0
2 changed files with 316 additions and 0 deletions
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OpenNest.Tests/EllipseConverterTests.cs
+171
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@@ -78,4 +78,175 @@ public class EllipseConverterTests
var center = EllipseConverter.IntersectNormals(p1, n1, p2, n2);
Assert.False(center.IsValid());
}
[Fact]
public void Convert_Circle_ProducesOneOrTwoArcs()
{
var result = EllipseConverter.Convert(
new Vector(0, 0), semiMajor: 10, semiMinor: 10, rotation: 0,
startParam: 0, endParam: Angle.TwoPI, tolerance: 0.001);
Assert.All(result, e => Assert.IsType<Arc>(e));
Assert.InRange(result.Count, 1, 4);
}
[Fact]
public void Convert_ModerateEllipse_AllArcsWithinTolerance()
{
var a = 10.0;
var b = 7.0;
var tolerance = 0.001;
var result = EllipseConverter.Convert(
new Vector(0, 0), a, b, rotation: 0,
startParam: 0, endParam: Angle.TwoPI, tolerance: tolerance);
Assert.True(result.Count >= 4, $"Expected at least 4 arcs, got {result.Count}");
Assert.All(result, e => Assert.IsType<Arc>(e));
foreach (var entity in result)
{
var arc = (Arc)entity;
var maxDev = MaxDeviationFromEllipse(arc, new Vector(0, 0), a, b, 0, 50);
Assert.True(maxDev <= tolerance,
$"Arc at center ({arc.Center.X:F4},{arc.Center.Y:F4}) r={arc.Radius:F4} " +
$"deviates {maxDev:F6} from ellipse (tolerance={tolerance})");
}
}
[Fact]
public void Convert_HighlyEccentricEllipse_ProducesMoreArcs()
{
var a = 20.0;
var b = 3.0;
var tolerance = 0.001;
var result = EllipseConverter.Convert(
new Vector(0, 0), a, b, rotation: 0,
startParam: 0, endParam: Angle.TwoPI, tolerance: tolerance);
Assert.True(result.Count >= 8, $"Expected at least 8 arcs for eccentric ellipse, got {result.Count}");
Assert.All(result, e => Assert.IsType<Arc>(e));
foreach (var entity in result)
{
var arc = (Arc)entity;
var maxDev = MaxDeviationFromEllipse(arc, new Vector(0, 0), a, b, 0, 50);
Assert.True(maxDev <= tolerance,
$"Deviation {maxDev:F6} exceeds tolerance {tolerance}");
}
}
[Fact]
public void Convert_PartialEllipse_CoversArcOnly()
{
var a = 10.0;
var b = 5.0;
var tolerance = 0.001;
var result = EllipseConverter.Convert(
new Vector(0, 0), a, b, rotation: 0,
startParam: 0, endParam: System.Math.PI / 2, tolerance: tolerance);
Assert.NotEmpty(result);
Assert.All(result, e => Assert.IsType<Arc>(e));
var firstArc = (Arc)result[0];
var sp = firstArc.StartPoint();
Assert.InRange(sp.X, a - 0.01, a + 0.01);
Assert.InRange(sp.Y, -0.01, 0.01);
var lastArc = (Arc)result[^1];
var ep = lastArc.EndPoint();
Assert.InRange(ep.X, -0.01, 0.01);
Assert.InRange(ep.Y, b - 0.01, b + 0.01);
}
[Fact]
public void Convert_EndpointContinuity_ArcsConnect()
{
var result = EllipseConverter.Convert(
new Vector(5, 10), semiMajor: 15, semiMinor: 8, rotation: 0.5,
startParam: 0, endParam: Angle.TwoPI, tolerance: 0.001);
for (var i = 0; i < result.Count - 1; i++)
{
var current = (Arc)result[i];
var next = (Arc)result[i + 1];
var gap = current.EndPoint().DistanceTo(next.StartPoint());
Assert.True(gap < 0.001,
$"Gap of {gap:F6} between arc {i} and arc {i + 1}");
}
var lastArc = (Arc)result[^1];
var firstArc = (Arc)result[0];
var closingGap = lastArc.EndPoint().DistanceTo(firstArc.StartPoint());
Assert.True(closingGap < 0.001,
$"Closing gap of {closingGap:F6}");
}
[Fact]
public void Convert_WithRotationAndOffset_ProducesValidArcs()
{
var center = new Vector(50, -30);
var rotation = System.Math.PI / 3;
var a = 12.0;
var b = 6.0;
var tolerance = 0.001;
var result = EllipseConverter.Convert(center, a, b, rotation,
startParam: 0, endParam: Angle.TwoPI, tolerance: tolerance);
Assert.NotEmpty(result);
foreach (var entity in result)
{
var arc = (Arc)entity;
var maxDev = MaxDeviationFromEllipse(arc, center, a, b, rotation, 50);
Assert.True(maxDev <= tolerance,
$"Deviation {maxDev:F6} exceeds tolerance {tolerance}");
}
}
private static double MaxDeviationFromEllipse(Arc arc, Vector ellipseCenter,
double semiMajor, double semiMinor, double rotation, int samples)
{
var maxDev = 0.0;
var sweep = arc.SweepAngle();
var startAngle = arc.StartAngle;
if (arc.IsReversed)
startAngle = arc.EndAngle;
for (var i = 0; i <= samples; i++)
{
var frac = (double)i / samples;
var angle = startAngle + frac * sweep;
var px = arc.Center.X + arc.Radius * System.Math.Cos(angle);
var py = arc.Center.Y + arc.Radius * System.Math.Sin(angle);
var arcPoint = new Vector(px, py);
// Coarse search over 1000 samples
var bestT = 0.0;
var minDist = double.MaxValue;
for (var j = 0; j <= 1000; j++)
{
var t = (double)j / 1000 * Angle.TwoPI;
var ep2 = EllipseConverter.EvaluatePoint(semiMajor, semiMinor, rotation, ellipseCenter, t);
var dist = arcPoint.DistanceTo(ep2);
if (dist < minDist) { minDist = dist; bestT = t; }
}
// Refine with local bisection around bestT
var lo = bestT - Angle.TwoPI / 1000;
var hi = bestT + Angle.TwoPI / 1000;
for (var r = 0; r < 20; r++)
{
var t1 = lo + (hi - lo) / 3;
var t2 = lo + 2 * (hi - lo) / 3;
var d1 = arcPoint.DistanceTo(EllipseConverter.EvaluatePoint(semiMajor, semiMinor, rotation, ellipseCenter, t1));
var d2 = arcPoint.DistanceTo(EllipseConverter.EvaluatePoint(semiMajor, semiMinor, rotation, ellipseCenter, t2));
if (d1 < d2) hi = t2; else lo = t1;
}
var bestDist = arcPoint.DistanceTo(EllipseConverter.EvaluatePoint(semiMajor, semiMinor, rotation, ellipseCenter, (lo + hi) / 2));
if (bestDist > maxDev) maxDev = bestDist;
}
return maxDev;
}
}