Add arc at polyline vertex

theswamp

Extension methods

• 1. static class Extensions

  2. {

  3. /// <summary>

  4. /// Adds an arc (fillet), if able, at each polyline vertex.

  5. /// </summary>

  6. /// <param name="pline">The instance to which the method applies.</param>

  7. /// <param name="radius">The arc radius.</param>

  8. public static void FilletAll(this Polyline pline, double radius)

  9. {

  10. int j = pline.Closed ? 0 : 1;

  11. for (int i = j; i < pline.NumberOfVertices - j; i++)

  12. {

  13. i += pline.FilletAt(i, radius);

  14. }

  15. }

  17. /// <summary>

  18. /// Adds an arc (fillet) at the specified vertex.

  19. /// </summary>

  20. /// <param name="pline">The instance to which the method applies.</param>

  21. /// <param name="index">The index of the verex.</param>

  22. /// <param name="radius">The arc radius.</param>

  23. /// <returns>1 if the operation succeeded, 0 if it failed.</returns>

  24. public static int FilletAt(this Polyline pline, int index, double radius)

  25. {

  26. int prev = index == 0 && pline.Closed ? pline.NumberOfVertices - 1 : index - 1;

  27. if (pline.GetSegmentType(prev) != SegmentType.Line ||

  28. pline.GetSegmentType(index) != SegmentType.Line)

  29. {

  30. return 0;

  31. }

  32. LineSegment2d seg1 = pline.GetLineSegment2dAt(prev);

  33. LineSegment2d seg2 = pline.GetLineSegment2dAt(index);

  34. Vector2d vec1 = seg1.StartPoint - seg1.EndPoint;

  35. Vector2d vec2 = seg2.EndPoint - seg2.StartPoint;

  36. double angle = vec1.GetAngleTo(vec2) / 2.0;

  37. double dist = radius / Math.Tan(angle);

  38. if (dist > seg1.Length || dist > seg2.Length)

  39. {

  40. return 0;

  41. }

  42. Point2d pt1 = seg1.EndPoint + vec1.GetNormal() * dist;

  43. Point2d pt2 = seg2.StartPoint + vec2.GetNormal() * dist;

  44. double bulge = Math.Tan((Math.PI / 2.0 - angle) / 2.0);

  45. if (Clockwise(seg1.StartPoint, seg1.EndPoint, seg2.EndPoint))

  46. {

  47. bulge = -bulge;

  48. }

  49. pline.AddVertexAt(index, pt1, bulge, 0.0, 0.0);

  50. pline.SetPointAt(index + 1, pt2);

  51. return 1;

  52. }

  54. /// <summary>

  55. /// Evaluates if the points are clockwise.

  56. /// </summary>

  57. /// <param name="p1">First point.</param>

  58. /// <param name="p2">Second point</param>

  59. /// <param name="p3">Third point</param>

  60. /// <returns>True if points are clockwise, False otherwise.</returns>

  61. private static bool Clockwise(Point2d p1, Point2d p2, Point2d p3)

  62. {

  63. return ((p2.X - p1.X) * (p3.Y - p1.Y) - (p2.Y - p1.Y) * (p3.X - p1.X)) < 1e-8;

  64. }

  65. }

Testing command

• 1. public class CommandMethods

  2. {

  3. [CommandMethod("Test", CommandFlags.Modal)]

  4. public void Test()

  5. {

  6. Document doc = AcAp.DocumentManager.MdiActiveDocument;

  7. Database db = doc.Database;

  8. Editor ed = doc.Editor;

  10. PromptDistanceOptions pdo = new PromptDistanceOptions("\nFillet radius: ");

  11. pdo.AllowZero = false;

  12. pdo.AllowNegative = false;

  13. PromptDoubleResult pdr = ed.GetDistance(pdo);

  14. if (pdr.Status != PromptStatus.OK)

  15. return;

  16. double radius = pdr.Value;

  18. PromptEntityOptions peo = new PromptEntityOptions("\nSelect a polyline: ");

  19. peo.SetRejectMessage("Not a polyline.");

  20. peo.AddAllowedClass(typeof(Polyline), true);

  21. PromptEntityResult per = ed.GetEntity(peo);

  22. if (per.Status != PromptStatus.OK)

  23. return;

  25. using (Transaction tr = db.TransactionManager.StartTransaction())

  26. {

  27. Polyline pline = (Polyline)tr.GetObject(per.ObjectId, OpenMode.ForWrite);

  28. pline.FilletAll(radius);

  29. tr.Commit();

  30. }

  31. }

  32. }