fix: assign colors to SpecialLayers and ConvertProgram entities

ConvertProgram.ToGeometry() created entities without setting Color,
defaulting to Color.Empty (alpha=0). After ededc7b switched from
Pens.White to per-entity colors, these rendered fully transparent.

- Add explicit colors to all SpecialLayers (Cut=White, Rapid=Gray, etc.)
- Set entity Color from layer in ConvertProgram for lines, arcs, circles
- Add GetEntityPen fallback: treat Empty/alpha-0 as White
- Add bend line rendering and selection in EntityView/CadConverterForm
- Fix SolidWorksBendDetector MText formatting strip for bend notes

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

OpenNest.Core/Converters/ConvertProgram.cs

@@ -59,9 +59,11 @@ namespace OpenNest.Converters
             if (mode == Mode.Incremental)
                 pt += curpos;
 
+            var layer = ConvertLayer(linearMove.Layer);
             var line = new Line(curpos, pt)
             {
-                Layer = ConvertLayer(linearMove.Layer)
+                Layer = layer,
+                Color = layer.Color
             };
             geometry.Add(line);
             curpos = pt;
@@ -76,7 +78,8 @@ namespace OpenNest.Converters
 
             var line = new Line(curpos, pt)
             {
-                Layer = SpecialLayers.Rapid
+                Layer = SpecialLayers.Rapid,
+                Color = SpecialLayers.Rapid.Color
             };
             geometry.Add(line);
             curpos = pt;
@@ -103,9 +106,9 @@ namespace OpenNest.Converters
             var layer = ConvertLayer(arcMove.Layer);
 
             if (startAngle.IsEqualTo(endAngle))
-                geometry.Add(new Circle(center, radius) { Layer = layer });
+                geometry.Add(new Circle(center, radius) { Layer = layer, Color = layer.Color });
             else
-                geometry.Add(new Arc(center, radius, startAngle, endAngle, arcMove.Rotation == RotationType.CW) { Layer = layer });
+                geometry.Add(new Arc(center, radius, startAngle, endAngle, arcMove.Rotation == RotationType.CW) { Layer = layer, Color = layer.Color });
 
             curpos = endpt;
         }

OpenNest.Core/SpecialLayers.cs

@@ -1,21 +1,22 @@
-using OpenNest.Geometry;
+using System.Drawing;
+using OpenNest.Geometry;
 
 namespace OpenNest
 {
     public static class SpecialLayers
     {
-        public static readonly Layer Default = new Layer("0");
+        public static readonly Layer Default = new Layer("0") { Color = Color.White };
 
-        public static readonly Layer Cut = new Layer("CUT");
+        public static readonly Layer Cut = new Layer("CUT") { Color = Color.White };
 
-        public static readonly Layer Rapid = new Layer("RAPID");
+        public static readonly Layer Rapid = new Layer("RAPID") { Color = Color.Gray };
 
-        public static readonly Layer Display = new Layer("DISPLAY");
+        public static readonly Layer Display = new Layer("DISPLAY") { Color = Color.Cyan };
 
-        public static readonly Layer Leadin = new Layer("LEADIN");
+        public static readonly Layer Leadin = new Layer("LEADIN") { Color = Color.Yellow };
 
-        public static readonly Layer Leadout = new Layer("LEADOUT");
+        public static readonly Layer Leadout = new Layer("LEADOUT") { Color = Color.Yellow };
 
-        public static readonly Layer Scribe = new Layer("SCRIBE");
+        public static readonly Layer Scribe = new Layer("SCRIBE") { Color = Color.Magenta };
     }
 }

OpenNest.IO/Bending/SolidWorksBendDetector.cs

@@ -17,9 +17,13 @@ namespace OpenNest.IO.Bending
         public double MaxBendRadius { get; set; } = 4.0;
 
         private static readonly Regex BendNoteRegex = new Regex(
-            @"\b(?<direction>UP|DOWN|DN)\s+(?<angle>\d+(\.\d+)?)°?\s*R\s*(?<radius>\d+(\.\d+)?)\b",
+            @"(?<direction>UP|DOWN|DN)\s+(?<angle>\d+(\.\d+)?)[^A-Z\d]*R\s*(?<radius>\d+(\.\d+)?)",
             RegexOptions.Compiled | RegexOptions.IgnoreCase);
 
+        private static readonly Regex MTextFormatRegex = new Regex(
+            @"\\[fHCTQWASpOoLlKk][^;]*;|\\P|[{}]|%%[dDpPcC]",
+            RegexOptions.Compiled);
+
         public List<Bend> DetectBends(CadDocument document)
         {
             var bendLines = FindBendLines(document);
@@ -45,9 +49,10 @@ namespace OpenNest.IO.Bending
                 var note = FindClosestBendNote(line, bendNotes);
                 if (note != null)
                 {
-                    bend.Direction = GetBendDirection(note.Value);
+                    var noteText = StripMTextFormatting(note.Value);
-                    bend.NoteText = note.Value;
+                    bend.Direction = GetBendDirection(noteText);
-                    ParseBendNote(note.Value, bend);
+                    bend.NoteText = noteText;
+                    ParseBendNote(noteText, bend);
                 }
 
                 if (!bend.Radius.HasValue || bend.Radius.Value <= MaxBendRadius)
@@ -106,6 +111,24 @@ namespace OpenNest.IO.Bending
             }
         }
 
+        private static string StripMTextFormatting(string text)
+        {
+            if (string.IsNullOrEmpty(text))
+                return text;
+
+            // Replace known DXF special characters
+            var result = text
+                .Replace("%%d", "°").Replace("%%D", "°")
+                .Replace("%%p", "±").Replace("%%P", "±")
+                .Replace("%%c", "⌀").Replace("%%C", "⌀");
+
+            // Strip MText formatting codes and braces
+            result = MTextFormatRegex.Replace(result, " ");
+
+            // Collapse multiple spaces
+            return Regex.Replace(result.Trim(), @"\s+", " ");
+        }
+
         private MText FindClosestBendNote(ACadSharp.Entities.Line bendLine, List<MText> notes)
         {
             if (notes.Count == 0) return null;

OpenNest/Controls/EntityView.cs

@@ -1,4 +1,5 @@
-using OpenNest.Geometry;
+using OpenNest.Bending;
+using OpenNest.Geometry;
 using OpenNest.Math;
 using System.Collections.Generic;
 using System.Drawing;
@@ -10,6 +11,8 @@ namespace OpenNest.Controls
     public class EntityView : DrawControl
     {
         public List<Entity> Entities;
+        public List<Bend> Bends = new List<Bend>();
+        public int SelectedBendIndex = -1;
 
         private readonly Pen gridPen = new Pen(Color.FromArgb(70, 70, 70));
         private readonly Dictionary<int, Pen> penCache = new Dictionary<int, Pen>();
@@ -49,6 +52,8 @@ namespace OpenNest.Controls
                 DrawEntity(e.Graphics, entity, pen);
             }
 
+            DrawBendLines(e.Graphics);
+
 #if DRAW_OFFSET
 
             var offsetShape = new Shape();
@@ -106,6 +111,9 @@ namespace OpenNest.Controls
 
         private Pen GetEntityPen(Color color)
         {
+            if (color.IsEmpty || color.A == 0)
+                color = Color.White;
+
             // Clamp dark colors to ensure visibility on dark background
             var brightness = (color.R * 299 + color.G * 587 + color.B * 114) / 1000;
             if (brightness < 80)
@@ -130,6 +138,29 @@ namespace OpenNest.Controls
             penCache.Clear();
         }
 
+        private void DrawBendLines(Graphics g)
+        {
+            if (Bends == null || Bends.Count == 0)
+                return;
+
+            using var bendPen = new Pen(Color.Yellow, 1.5f)
+            {
+                DashStyle = DashStyle.Dash
+            };
+            using var selectedPen = new Pen(Color.Cyan, 2.5f)
+            {
+                DashStyle = DashStyle.Dash
+            };
+
+            for (var i = 0; i < Bends.Count; i++)
+            {
+                var bend = Bends[i];
+                var pt1 = PointWorldToGraph(bend.StartPoint);
+                var pt2 = PointWorldToGraph(bend.EndPoint);
+                g.DrawLine(i == SelectedBendIndex ? selectedPen : bendPen, pt1, pt2);
+            }
+        }
+
         protected override void Dispose(bool disposing)
         {
             if (disposing)

OpenNest/Forms/CadConverterForm.cs

@@ -134,6 +134,7 @@ namespace OpenNest.Forms
             entityView1.ClearPenCache();
             entityView1.Entities.Clear();
             entityView1.Entities.AddRange(item.Entities);
+            entityView1.Bends = item.Bends ?? new List<Bend>();
 
             item.Entities.ForEach(e => e.IsVisible = true);
             if (item.Entities.Any(e => e.Layer != null))
@@ -174,7 +175,7 @@ namespace OpenNest.Forms
 
         private void OnBendLineSelected(object sender, int index)
         {
-            // TODO: Highlight bend line in EntityView
+            entityView1.SelectedBendIndex = index;
             entityView1.Invalidate();
         }
 
@@ -184,6 +185,8 @@ namespace OpenNest.Forms
             if (item == null || index < 0 || index >= item.Bends.Count) return;
 
             item.Bends.RemoveAt(index);
+            entityView1.Bends = item.Bends;
+            entityView1.SelectedBendIndex = -1;
             filterPanel.LoadItem(item.Entities, item.Bends);
             entityView1.Invalidate();
         }