Delphi type TJoinType = (jtSquare, jtRound, jtMiter);

C++ enum JoinType {Square, Round, Miter};

C#  public enum JoinType {Square, Round, Miter};

The JoinType enumerator is only needed when offsetting (inflating/shrinking). It isn't needed for polygon clipping.

When adding paths to a ClipperOffset object via the AddPaths method, the joinType parameter may be any one of these types - Square, Round or Miter.

The angle at vertex A is more acute than the one at B and a mitered offset there would exceed 'miter limit'.

See Also

Clipper.Offset, ClipperOffset, ClipperOffset.AddPaths, ClipperOffset.MiterLimit