public RailSegment(RailSegment source, RailPiece railPiece, bool copyCurve)
 {
     RailPiece = railPiece;
     Curve     = copyCurve ? new BezierCurve3(source.Curve) : source.Curve;
 }
 public RailSegment(BezierCurve3 curve, RailPiece railPiece)
 {
     RailPiece = railPiece;
     Curve     = curve;
 }