The following sample code demonstrates how to determine a selected object's layer name using the Rhino SDK.

C++

  CRhinoCommand::result CCommandTest::RunCommand( const CRhinoCommandContext& context )
  {
    CRhinoGetObject go;
    go.SetCommandPrompt( L"Select object" );
    go.GetObjects( 1, 1 );
    if( go.CommandResult() != CRhinoCommand::success )
      return go.CommandResult();


    const CRhinoObjRef& objref = go.Object(0);
    const CRhinoObject* object = objref.Object();
    if( !object )
      return CRhinoCommand::failure;


    const CRhinoObjectAttributes& attributes = object->Attributes();
    int layer_index = attributes.m_layer_index;


    const CRhinoLayerTable& layer_table = context.m_doc.m_layer_table;
    const CRhinoLayer& layer = layer_table[layer_index];
    ON_wString layer_name = layer.LayerName();
    RhinoApp().Print( L"The selected object's layer is \"%s\"\n", layer_name );


    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 object")
    go.GetObjects(1, 1)
    If (go.CommandResult() <> IRhinoCommand.result.success) Then
      Return go.CommandResult()
    End If


    Dim objref As IRhinoObjRef = go.Object(0)
    Dim obj As IRhinoObject = objref.Object()
    If (obj Is Nothing) Then Return IRhinoCommand.result.failure


    Dim attributes As IRhinoObjectAttributes = obj.Attributes()
    Dim layer_index As Integer = attributes.m_layer_index


    Dim layer_table As IRhinoLayerTable = context.m_doc.m_layer_table
    Dim layer As IRhinoLayer = layer_table(layer_index)
    Dim layer_name As String = layer.LayerName()
    Dim msg As String = _
        String.Format("The selected object's layer is '{0}'" + vbCrLf, layer_name)
    RhUtil.RhinoApp.Print(msg)
    Return IRhinoCommand.result.success
  End Function

C# (Rhino 4)

  public override IRhinoCommand.result RunCommand(IRhinoCommandContext context)
  {
    MRhinoGetObject go = new MRhinoGetObject();
    go.SetCommandPrompt("Select object");
    go.GetObjects(1, 1);
    if(go.CommandResult() != IRhinoCommand.result.success)
      return go.CommandResult();


    IRhinoObjRef objref = go.Object(0);
    IRhinoObject obj = objref.Object();
    if(obj == null)
      return IRhinoCommand.result.failure;


    IRhinoObjectAttributes attributes = obj.Attributes();
    int layer_index = attributes.m_layer_index;


    IRhinoLayerTable layer_table = context.m_doc.m_layer_table;
    IRhinoLayer layer = layer_table[layer_index];
    string layer_name = layer.LayerName();
    string msg = string.Format("The selected object's layer is '{0}'\n", layer_name);
    RhUtil.RhinoApp().Print(msg);
    return IRhinoCommand.result.success;
  }