BuildingCoder.CmdRoomNeighbours.GetRoomNeighbourAt C# (CSharp) Method

        Room GetRoomNeighbourAt( 
            BoundarySegment bs,
            Room r)
        {
            Document doc = r.Document;

              //Wall w = bs.Element as Wall;// 2015
              Wall w = doc.GetElement( bs.ElementId ) as Wall;// 2016

              double wallThickness = w.Width;

              double wallLength = ( w.Location as
            LocationCurve ).Curve.Length;

              Transform derivatives = bs.GetCurve()
            .ComputeDerivatives(  0.5, true );

              XYZ midPoint = derivatives.Origin;

              Debug.Assert(
            midPoint.IsAlmostEqualTo(
              bs.GetCurve().Evaluate( 0.5, true ) ),
            "expected same result from Evaluate and derivatives" );

              XYZ tangent = derivatives.BasisX.Normalize();

              XYZ normal = new XYZ( tangent.Y,
            tangent.X * ( -1 ), tangent.Z );

              XYZ p = midPoint + wallThickness * normal;

              Room otherRoom = doc.GetRoomAtPoint( p );

              if( null != otherRoom )
              {
            if( otherRoom.Id == r.Id )
            {
              normal = new XYZ( tangent.Y * ( -1 ),
            tangent.X, tangent.Z );

              p = midPoint + wallThickness * normal;

              otherRoom = doc.GetRoomAtPoint( p );

              Debug.Assert( null == otherRoom
              || otherRoom.Id != r.Id,
            "expected different room on other side" );
            }
              }
              return otherRoom;
        }