bool getConstraintPrerequisits(Fem::FemAnalysis **Analysis)
{
    Fem::FemAnalysis* ActiveAnalysis = FemGui::ActiveAnalysisObserver::instance()->getActiveObject();
    if (!ActiveAnalysis || !ActiveAnalysis->getTypeId().isDerivedFrom(Fem::FemAnalysis::getClassTypeId())){
        QMessageBox::warning(Gui::getMainWindow(), QObject::tr("No active Analysis"),
                QObject::tr("You need to create or activate a Analysis"));
        return true;
    }

    *Analysis = static_cast<Fem::FemAnalysis*>(ActiveAnalysis);

    // return with no error
    return false;

}

void CmdFemConstraintPressure::activated(int iMsg)
{
    Fem::FemAnalysis        *Analysis;

    if(getConstraintPrerequisits(&Analysis))
        return;

    std::string FeatName = getUniqueObjectName("FemConstraintPressure");

    openCommand("Make FEM constraint pressure on face");
    doCommand(Doc,"App.activeDocument().addObject(\"Fem::ConstraintPressure\",\"%s\")",FeatName.c_str());
    doCommand(Doc,"App.activeDocument().%s.Pressure = 0.0",FeatName.c_str());
    doCommand(Doc,"App.activeDocument().%s.Member = App.activeDocument().%s.Member + [App.activeDocument().%s]",
              Analysis->getNameInDocument(),Analysis->getNameInDocument(),FeatName.c_str());
    updateActive();

    doCommand(Gui,"Gui.activeDocument().setEdit('%s')",FeatName.c_str());
}

void CmdFemConstraintPulley::activated(int iMsg)
{
    Fem::FemAnalysis        *Analysis;

    if(getConstraintPrerequisits(&Analysis))
        return;

    std::string FeatName = getUniqueObjectName("FemConstraintPulley");

    openCommand("Make FEM constraint for pulley");
    doCommand(Doc,"App.activeDocument().addObject(\"Fem::ConstraintPulley\",\"%s\")",FeatName.c_str());
    doCommand(Doc,"App.activeDocument().%s.Diameter = 300.0",FeatName.c_str());
    doCommand(Doc,"App.activeDocument().%s.OtherDiameter = 100.0",FeatName.c_str());
    doCommand(Doc,"App.activeDocument().%s.CenterDistance = 500.0",FeatName.c_str());
    doCommand(Doc,"App.activeDocument().%s.Force = 100.0",FeatName.c_str());
    doCommand(Doc,"App.activeDocument().%s.TensionForce = 100.0",FeatName.c_str());
    doCommand(Doc,"App.activeDocument().%s.Member = App.activeDocument().%s.Member + [App.activeDocument().%s]",Analysis->getNameInDocument(),Analysis->getNameInDocument(),FeatName.c_str());
    updateActive();

    doCommand(Gui,"Gui.activeDocument().setEdit('%s')",FeatName.c_str());
}

void DefineNodesCallback(void * ud, SoEventCallback * n)
{
    Fem::FemAnalysis        *Analysis;

    if(getConstraintPrerequisits(&Analysis))
        return;

    // show the wait cursor because this could take quite some time
    Gui::WaitCursor wc;

    // When this callback function is invoked we must in either case leave the edit mode
    Gui::View3DInventorViewer* view  = reinterpret_cast<Gui::View3DInventorViewer*>(n->getUserData());
    view->setEditing(false);
    view->removeEventCallback(SoMouseButtonEvent::getClassTypeId(), DefineNodesCallback,ud);
    n->setHandled();

    SbBool clip_inner;
    std::vector<SbVec2f> clPoly = view->getGLPolygon(&clip_inner);
    if (clPoly.size() < 3)
        return;
    if (clPoly.front() != clPoly.back())
        clPoly.push_back(clPoly.front());

    SoCamera* cam = view->getCamera();
    SbViewVolume vv = cam->getViewVolume();
    Gui::ViewVolumeProjection proj(vv);
    Base::Polygon2D polygon;
    for (std::vector<SbVec2f>::const_iterator it = clPoly.begin(); it != clPoly.end(); ++it)
        polygon.Add(Base::Vector2D((*it)[0],(*it)[1]));


    std::vector<App::DocumentObject*> docObj = Gui::Selection().getObjectsOfType(Fem::FemMeshObject::getClassTypeId());
    if(docObj.size() !=1)
        return;

    const SMESHDS_Mesh* data = const_cast<SMESH_Mesh*>(dynamic_cast<Fem::FemMeshObject*>(docObj[0])->FemMesh.getValue().getSMesh())->GetMeshDS();

    SMDS_NodeIteratorPtr aNodeIter = data->nodesIterator();
    Base::Vector3f pt2d;
    std::set<int> IntSet;

    for (int i=0;aNodeIter->more();) {
        const SMDS_MeshNode* aNode = aNodeIter->next();
        Base::Vector3f vec(aNode->X(),aNode->Y(),aNode->Z());
        pt2d = proj(vec);
        if (polygon.Contains(Base::Vector2D(pt2d.x, pt2d.y)) == true) 
            IntSet.insert(aNode->GetID());
    }
    
    std::stringstream  set;

    set << "[";
    for(std::set<int>::const_iterator it=IntSet.begin();it!=IntSet.end();++it)
        if(it==IntSet.begin())
            set << *it ;
        else
            set << "," << *it ;
    set << "]";

    
    Gui::Command::openCommand("Place robot");
    Gui::Command::doCommand(Gui::Command::Doc,"App.ActiveDocument.addObject('Fem::FemSetNodesObject','NodeSet')");
    Gui::Command::doCommand(Gui::Command::Doc,"App.ActiveDocument.ActiveObject.Nodes = %s",set.str().c_str());
    Gui::Command::doCommand(Gui::Command::Doc,"App.activeDocument().%s.Member = App.activeDocument().%s.Member + [App.activeDocument().NodeSet]",Analysis->getNameInDocument(),Analysis->getNameInDocument());
    ////Gui::Command::updateActive();
    Gui::Command::commitCommand();

    //std::vector<Gui::ViewProvider*> views = view->getViewProvidersOfType(ViewProviderMesh::getClassTypeId());
    //if (!views.empty()) {
    //    Gui::Application::Instance->activeDocument()->openCommand("Cut");
    //    for (std::vector<Gui::ViewProvider*>::iterator it = views.begin(); it != views.end(); ++it) {
    //        ViewProviderMesh* that = static_cast<ViewProviderMesh*>(*it);
    //        if (that->getEditingMode() > -1) {
    //            that->finishEditing();
    //            that->cutMesh(clPoly, *view, clip_inner);
    //        }
    //    }

    //    Gui::Application::Instance->activeDocument()->commitCommand();

    //    view->render();
    //}
}