feat: add option to round lead-in angles for circle holes

Snaps lead-in angles on ArcCircle contours to a configurable
increment (default 5°), reducing unique hole variations from
infinite to 72 max. Rounding happens upstream in EmitContour
so the PlateView and post output stay in sync.

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

OpenNest.Core/CNC/CuttingStrategy/ContourCuttingStrategy.cs

@@ -255,7 +255,23 @@ namespace OpenNest.CNC.CuttingStrategy
             var leadOut = SelectLeadOut(contourType);
 
             if (contourType == ContourType.ArcCircle && entity is Circle circle)
+            {
+                if (Parameters.RoundLeadInAngles && Parameters.LeadInAngleIncrement > 0)
+                {
+                    var increment = Angle.ToRadians(Parameters.LeadInAngleIncrement);
+                    normal = System.Math.Round(normal / increment) * increment;
+                    normal = Angle.NormalizeRad(normal);
+
+                    // Recompute contour start point on the circle at the rounded angle.
+                    // For ArcCircle, normal points inward (toward center), so outward = normal - PI.
+                    var outwardAngle = normal - System.Math.PI;
+                    point = new Vector(
+                        circle.Center.X + circle.Radius * System.Math.Cos(outwardAngle),
+                        circle.Center.Y + circle.Radius * System.Math.Sin(outwardAngle));
+                }
+
                 leadIn = ClampLeadInForCircle(leadIn, circle, point, normal);
+            }
 
             program.Codes.AddRange(leadIn.Generate(point, normal, winding));
 

OpenNest.Core/CNC/CuttingStrategy/CuttingParameters.cs

@@ -23,6 +23,9 @@ namespace OpenNest.CNC.CuttingStrategy
 
         public double PierceClearance { get; set; } = 0.0625;
 
+        public bool RoundLeadInAngles { get; set; }
+        public double LeadInAngleIncrement { get; set; } = 5.0;
+
         public double AutoTabMinSize { get; set; }
         public double AutoTabMaxSize { get; set; }
 

OpenNest/Controls/CuttingPanel.cs

@@ -28,6 +28,9 @@ namespace OpenNest.Controls
         private readonly NumericUpDown nudAutoTabMax;
         private readonly NumericUpDown nudPierceClearance;
 
+        private readonly CheckBox chkRoundLeadInAngles;
+        private readonly NumericUpDown nudLeadInAngleIncrement;
+
         private readonly Button btnAutoAssign;
 
         private bool suppressEvents;
@@ -162,7 +165,7 @@ namespace OpenNest.Controls
             {
                 HeaderText = "Pierce",
                 Dock = DockStyle.Top,
-                ExpandedHeight = 60,
+                ExpandedHeight = 90,
                 IsExpanded = true
             };
 
@@ -176,6 +179,34 @@ namespace OpenNest.Controls
             nudPierceClearance = CreateNumeric(130, 3, 0.0625, 0.0625);
             piercePanel.ContentPanel.Controls.Add(nudPierceClearance);
 
+            chkRoundLeadInAngles = new CheckBox
+            {
+                Text = "Round Lead-In Angles",
+                Location = new Point(12, 32),
+                AutoSize = true
+            };
+            chkRoundLeadInAngles.CheckedChanged += (s, e) =>
+            {
+                nudLeadInAngleIncrement.Enabled = chkRoundLeadInAngles.Checked;
+                OnParametersChanged();
+            };
+            piercePanel.ContentPanel.Controls.Add(chkRoundLeadInAngles);
+
+            piercePanel.ContentPanel.Controls.Add(new Label
+            {
+                Text = "Increment:",
+                Location = new Point(175, 34),
+                AutoSize = true
+            });
+
+            nudLeadInAngleIncrement = CreateNumeric(245, 31, 5, 1);
+            nudLeadInAngleIncrement.DecimalPlaces = 0;
+            nudLeadInAngleIncrement.Minimum = 1;
+            nudLeadInAngleIncrement.Maximum = 90;
+            nudLeadInAngleIncrement.Enabled = false;
+            nudLeadInAngleIncrement.ValueChanged += (s, e) => OnParametersChanged();
+            piercePanel.ContentPanel.Controls.Add(nudLeadInAngleIncrement);
+
             // Auto-Assign button — wrapped in a panel for Dock.Top with padding
             btnAutoAssign = new Button
             {
@@ -218,6 +249,8 @@ namespace OpenNest.Controls
                 TabsEnabled = chkTabsEnabled.Checked,
                 TabConfig = new NormalTab { Size = (double)nudTabWidth.Value },
                 PierceClearance = (double)nudPierceClearance.Value,
+                RoundLeadInAngles = chkRoundLeadInAngles.Checked,
+                LeadInAngleIncrement = (double)nudLeadInAngleIncrement.Value,
                 AutoTabMinSize = (double)nudAutoTabMin.Value,
                 AutoTabMaxSize = (double)nudAutoTabMax.Value
             };
@@ -238,6 +271,9 @@ namespace OpenNest.Controls
             if (p.TabConfig != null)
                 nudTabWidth.Value = (decimal)p.TabConfig.Size;
             nudPierceClearance.Value = (decimal)p.PierceClearance;
+            chkRoundLeadInAngles.Checked = p.RoundLeadInAngles;
+            nudLeadInAngleIncrement.Value = (decimal)p.LeadInAngleIncrement;
+            nudLeadInAngleIncrement.Enabled = p.RoundLeadInAngles;
             nudAutoTabMin.Value = (decimal)p.AutoTabMinSize;
             nudAutoTabMax.Value = (decimal)p.AutoTabMaxSize;
 

OpenNest/Forms/CuttingParametersSerializer.cs

@@ -24,6 +24,8 @@ namespace OpenNest.Forms
                 TabsEnabled = p.TabsEnabled,
                 TabWidth = p.TabConfig?.Size ?? 0.25,
                 PierceClearance = p.PierceClearance,
+                RoundLeadInAngles = p.RoundLeadInAngles,
+                LeadInAngleIncrement = p.LeadInAngleIncrement,
                 AutoTabMinSize = p.AutoTabMinSize,
                 AutoTabMaxSize = p.AutoTabMaxSize
             };
@@ -47,6 +49,8 @@ namespace OpenNest.Forms
                 TabsEnabled = dto.TabsEnabled,
                 TabConfig = new NormalTab { Size = dto.TabWidth },
                 PierceClearance = dto.PierceClearance,
+                RoundLeadInAngles = dto.RoundLeadInAngles,
+                LeadInAngleIncrement = dto.LeadInAngleIncrement > 0 ? dto.LeadInAngleIncrement : 5.0,
                 AutoTabMinSize = dto.AutoTabMinSize,
                 AutoTabMaxSize = dto.AutoTabMaxSize
             };
@@ -111,6 +115,8 @@ namespace OpenNest.Forms
             public bool TabsEnabled { get; set; }
             public double TabWidth { get; set; }
             public double PierceClearance { get; set; }
+            public bool RoundLeadInAngles { get; set; }
+            public double LeadInAngleIncrement { get; set; }
             public double AutoTabMinSize { get; set; }
             public double AutoTabMaxSize { get; set; }
         }