How to get a polyline from region

[reithinger]

Hi, 

I have a Problem.

I have a Region and i want to get a polyline from all the Region

The Red Line is the Region and the Green Line is the polyline that i have...

This isn't what a want.

I make this

// Regionen vereinigen und äußere Kontur als Polyline erzeugen
using (var reg = MergeRegions(regions, AcDataService.BooleanOperationType.BoolUnite))
{
   if (reg != null)
   {
      var brep = new AcBounds.Brep(reg);
      var points = new List<Point2d>();
      var face = brep.Faces.First();
      foreach (var loop in face.Loops)
      {
         if (loop.LoopType == AcBounds.LoopType.LoopExterior)
         {
            foreach (var vertex in loop.Vertices)
            {
               points.Add(new Point2d(vertex.Point.X, vertex.Point.Y));
            }
            break;
         }
      }
      // Polyline aus Punkten erzeugen
      myRegionPolyline = CreatePolyline(points);
   }
}
myRegionPolyline.ColorIndex = 3; // Set color index for the polyline
curSpace.AppendEntity(myRegionPolyline);
tr.AddNewlyCreatedDBObject(myRegionPolyline, true);

I make a Merge von Region with Unite and that i use the Brep, but something isn't correct.

What is my mystake ?

Thanks Fabrice

[_gile · Accepted solution]

Hi,

You can use the Region.GetCurves() extension method from GeometryExtensions library.

/// <summary>
/// Gets the curves constituting the boundaries of the region.
/// </summary>
/// <param name="region">The instance to which this method applies.</param>
/// <param name="tolerance">Tolerance used in curve end points comparison.</param>
/// <returns>Curve collection.</returns>
/// <exception cref="System.ArgumentNullException">ArgumentException is thrown if <paramref name="region"/> is null.</exception>
public static IEnumerable<Curve> GetCurves(this Region region, Tolerance tolerance = default)
{
    Assert.IsNotNull(region, nameof(region));

    if (tolerance.Equals(default(Tolerance)))
        tolerance = Tolerance.Global;

    using (var brep = new Brep(region))
    {
        foreach (var loop in brep.Faces.SelectMany(face => face.Loops))
        {
            var curves3d = loop.GetNativeCurves().ToArray();
            if (curves3d.Length == 1)
            {
                yield return Curve.CreateFromGeCurve(curves3d[0]);
            }
            else if (curves3d.TryConvertToCompositeCurve(out CompositeCurve3d compositeCurve, tolerance, c => c is LineSegment3d || c is CircularArc3d))
            {
                yield return (Polyline)Curve.CreateFromGeCurve(compositeCurve);
            }
            else
            {
                foreach (Curve3d curve3d in curves3d)
                {
                    yield return Curve.CreateFromGeCurve(curve3d);
                }
            }
        }
    }
}

[reithinger]

Hi _Gile,

thanks for your help.

Do you know why my code not really do ?

Thanks Fabrice

[_gile]

---

@reithinger  a écrit :

Do you know why my code not really do ?

---

Because your code uses the vertices (points) of the loop, instead of the edges (curves). The points do not contains the informations required to create the arc segments.

[reithinger]

Ok,

I Understand.

Thanks for your reply.

It works.

Thanks Fabrice