The openNURBS SDK, which is also included with the Rhino SDK, contains a ON_TextLog class that makes it very simple to write, or dump, information to a text file. The class can be very handy when trying to debug geometric objects, for most objects have the ability to dump their contents to a log file.

The following is an example of using the ON_TextLog class to dump the contents of a brep object to a text file. For more information on ON_TextLog, see opennurbs_textlog.h

C++

  CRhinoCommand::result CCommandTest::RunCommand( 
      const CRhinoCommandContext& context )
  {
    CRhinoGetObject go;
    go.SetCommandPrompt( L"Select brep" );
    go.SetGeometryFilter( 
         CRhinoGetObject::surface_object |
         CRhinoGetObject::polysrf_object );
    go.GetObjects( 1, 1 );
    if( go.CommandResult() == CRhinoCommand::success )
    {
      const ON_Brep* brep = go.Object(0).Brep();
      if( brep )
      {
        FILE* fp = ON::OpenFile( L"c:\\bug_report.txt", L"w" );
        if( fp )
        {
          ON_TextLog text_log( fp );
          text_log.Print( L"Dumping Brep...\n" );
          brep->Dump( text_log );
          ON::CloseFile( fp );
        }
      }
    }
    return CRhinoCommand::success;
  }

VB.NET (Rhino 4)

  Public Overrides Function RunCommand(ByVal context As IRhinoCommandContext) _
    As IRhinoCommand.result
    Dim go As New MRhinoGetObject()
    go.SetCommandPrompt("Select brep")
    go.SetGeometryFilter(IRhinoGetObject.GEOMETRY_TYPE_FILTER.polysrf_object _
                        Or IRhinoGetObject.GEOMETRY_TYPE_FILTER.surface_object)
    go.GetObjects(1, 1)
    If (go.CommandResult() = IRhinoCommand.result.success) Then
      Dim brep As IOnBrep = go.Object(0).Brep()
      If (brep IsNot Nothing) Then
        Dim fp As OnFileHandle = OnUtil.OpenFile("c:\\brep_info.txt", "w")
        If (fp IsNot Nothing) Then
          Dim text_log As New OnTextLog(fp)
          text_log.Print("Dumping Brep..." + vbCrLf)
          brep.Dump(text_log)
          OnUtil.CloseFile(fp)
        End If
      End If
    End If
    Return IRhinoCommand.result.success
  End Function

C# (Rhino 4)

  public override IRhinoCommand.result RunCommand(IRhinoCommandContext context)
  {
    MRhinoGetObject go = new MRhinoGetObject();
    go.SetCommandPrompt( "Select brep" );
    go.SetGeometryFilter( IRhinoGetObject.GEOMETRY_TYPE_FILTER .polysrf_object
                        | IRhinoGetObject.GEOMETRY_TYPE_FILTER.surface_object);
    go.GetObjects( 1, 1 );
    if( go.CommandResult() == IRhinoCommand.result.success )
    {
      IOnBrep brep = go.Object(0).Brep();
      if( brep != null )
      {
        OnFileHandle fp = OnUtil.OpenFile("c:\\brep_info.txt", "w" );
        if( fp != null )
        {
          OnTextLog text_log = new OnTextLog(fp);
          text_log.Print( "Dumping Brep...\n" );
          brep.Dump( ref text_log );
          OnUtil.CloseFile( fp );
        }
      }
    }
    return IRhinoCommand.result.success;
  }