C++

  CRhinoCommand::result CCommandTest::RunCommand(
          const CRhinoCommandContext& context )
  {
    CRhinoCommand::result rc = CRhinoCommand::cancel;


    // Get the active view object
    CRhinoView* view = ::RhinoApp().ActiveView();
    if( view )
    {
      // Get reference to the view's viewport object
      CRhinoViewport& vp = view->Viewport();
      // Create plane object based on viewport parameters
      ON_Plane plane( vp.Target(), vp.VP().CameraX(), vp.VP().CameraY() );
      // Copy viewport's cplane object
      ON_3dmConstructionPlane cplane = vp.ConstructionPlane();
      // Set the cplane's plane object
      cplane.m_plane = plane;
      // Push the new cplane onto the cplane stack
      view->Viewport().PushConstructionPlane( cplane );
      // Redraw the view
      view->Redraw();
      rc = CRhinoCommand::success;
    }
    return rc;
  }

VB.NET (Rhino 4)

  Public Overrides Function RunCommand(ByVal context As IRhinoCommandContext) _
    As IRhinoCommand.result


    Dim rc As IRhinoCommand.result = IRhinoCommand.result.cancel
    ' Get the active view object
    Dim view As MRhinoView = RhUtil.RhinoApp.ActiveView
    If (view IsNot Nothing) Then
      ' Get reference to the view's viewport object
      Dim vp As MRhinoViewport = view.ActiveViewport()
      ' Create plane object based on viewport parameters
      Dim plane As New OnPlane(vp.Target(), vp.VP().CameraX(), vp.VP.CameraY())
      ' Copy viewport's cplane object
      Dim cplane As New On3dmConstructionPlane(vp.ConstructionPlane())
      ' Set the cplane's plane object
      cplane.m_plane = plane
      ' Push the new cplane onto the cplane stack
      view.ActiveViewport().PushConstructionPlane(cplane)
      ' Redraw the view
      view.Redraw()
      rc = IRhinoCommand.result.success
    End If
    Return rc
  End Function

C# (Rhino 4)

  public override IRhinoCommand.result RunCommand(IRhinoCommandContext context)
  {
    IRhinoCommand.result rc = IRhinoCommand.result.cancel;
    // Get the active view object
    MRhinoView view = RhUtil.RhinoApp().ActiveView();
    if( view != null )
    {
      // Get reference to the view's viewport object
      MRhinoViewport vp = view.ActiveViewport();
      // Create plane object based on viewport parameters
      OnPlane plane = new OnPlane( vp.Target(), vp.VP().CameraX(), vp.VP().CameraY() );
      // Copy viewport's cplane object
      On3dmConstructionPlane cplane = new On3dmConstructionPlane(vp.ConstructionPlane());
      // Set the cplane's plane object
      cplane.m_plane = plane;
      // Push the new cplane onto the cplane stack
      view.ActiveViewport().PushConstructionPlane( cplane );
      // Redraw the view
      view.Redraw();
      rc = IRhinoCommand.result.success;
    }
    return rc;
  }