Sub ConvexHull()
  Dim pMxDoc As IMxDocument
  Dim pMap As IMap
  Dim pFeatureLayer As IFeatureLayer
  Dim pInFeatureClass As IFeatureClass
  Dim pOutFeatureClass As IFeatureClass
  Dim sMessage As String
  Set pMxDoc = ThisDocument
  Set pMap = pMxDoc.FocusMap
  Set pFeatureLayer = pMxDoc.SelectedLayer
  Set pInFeatureClass = pFeatureLayer.FeatureClass
  '=======================================================================
  Dim ET As New ETGW_Core
  Dim sOutFileName As String
  sOutFileName = "c:\00\test_pgdb.mdb\convex_hull"
  Set pOutFeatureClass = ET.ConvexHull(pInFeatureClass, sOutFileName, sMessage)
  '========================================================================
  If Not pOutFeatureClass Is Nothing Then
    Set pFeatureLayer = New FeatureLayer
    Set pFeatureLayer.FeatureClass = pOutFeatureClass
    pFeatureLayer.Name = pOutFeatureClass.AliasName
    pMap.AddLayer pFeatureLayer
  Else
    MsgBox sMessage
  End If
End Sub