Untitled

  public static Point3d PolylineCentroid(ZwSoft.ZwCAD.DatabaseServices.Polyline polyline)
  {
      double area = 0;
      double cx = 0;
      double cy = 0;
      int numVertices = polyline.NumberOfVertices;
      for (int i = 0; i < numVertices; i++)
      {
          Point2d p1 = polyline.GetPoint2dAt(i);
          Point2d p2 = polyline.GetPoint2dAt((i + 1) % numVertices);

          // Determinante para cálculo da área e dos centroides
          double determinant = (p1.X * p2.Y) - (p2.X * p1.Y);
          area += determinant;
          cx += (p1.X + p2.X) * determinant;
          cy += (p1.Y + p2.Y) * determinant;
      }
      area *= 0.5;
      cx = (cx / (6 * area));
      cy = (cy / (6 * area));
      return new Point3d(cx, cy, 0);
  }