[vtkusers] VTK centering vtkChartXY on polydata (Python)

[mafiaskafia]

I'm trying to implement a gridline behind a vtkPolydata Object that
represents a 2D mesh, so it's easier for the end-user to see it's
dimensions. I managed to implement a gridline using vtkChartXY, but i
couldn't figure out how i could set the origin of the gridline to be on the
center of the vtkPolyData object, and also how i could make the gridline
appear before the Object and not after like this:

<http://vtk.1045678.n5.nabble.com/file/t342418/halppp.png> 

This is the code i used to make the gridline:

        def openGL_Design(self):
        
            self.chart = vtk.vtkChartXY()
            self.plot = vtk.vtkPlotPoints()
            self.chart.AddPlot(self.plot)
        
            self.view = vtk.vtkContextActor()
            self.view.GetScene().AddItem(self.chart)
        
            #Create a Window interactor using the central frame object from
Qt
            self.vtkDesign = QVTKRenderWindowInteractor(self.centralFrame)
            self.vl = Qt.QVBoxLayout()
            self.vl.setContentsMargins(0, 0, 0, 0)
            self.vl.setSpacing(0)              
            self.vl.addWidget(self.vtkDesign)

            #Create a renderer and add it to the window
            self.renDesign = vtk.vtkRenderer()
            self.vtkDesign.GetRenderWindow().AddRenderer(self.renDesign)
            self.renDesign.SetBackground(.85, .85, .85) 
            self.irenDesign =
self.vtkDesign.GetRenderWindow().GetInteractor()
        
        
            #Set a dummy actor so i don't end up with repeated meshes
            self.MeshActor = vtk.vtkActor()
            self.centroidActor = vtk.vtkActor()
            self.renDesign.AddActor(self.view)
            self.renDesign.AddActor(self.MeshActor)
            self.renDesign.AddActor(self.centroidActor)
        
            self.centralFrame.setLayout(self.vl)
    
            self.show()
            self.irenDesign.Initialize()
            self.irenDesign.Start()

And this is the code i used to make the "Mesh Actor"

    def addVisual_Mesh(self):
        
        self.renDesign.RemoveActor(self.MeshActor) #Removes the old actor
        
        def mkVtkIdList(it):
            vil = vtk.vtkIdList()
            for i in it:
                vil.InsertNextId(int(i))
            return vil
        
        colors = vtk.vtkNamedColors() 
    
        #Array of vectors containing the coordinates of each point
        nodes = self.Results.nodes
    
        #Array of tuples containing the nodes correspondent of each element
        elements = self.Results.elements
    
        #Make the building blocks of polyData attributes
        Mesh = vtk.vtkPolyData()
        Points = vtk.vtkPoints()
        Cells = vtk.vtkCellArray()  
    
        #Load the point and cell's attributes
        for i in range(self.Results.numNodes):
            Points.InsertPoint(i, nodes[i])
        
        for i in range(self.Results.numElements):
            Cells.InsertNextCell(mkVtkIdList(elements[i]))
        
        #Assign pieces to vtkPolyData
        Mesh.SetPoints(Points)
        Mesh.SetPolys(Cells)
       
        #Mapping the whole thing
        MeshMapper = vtk.vtkPolyDataMapper()
        if vtk.VTK_MAJOR_VERSION <= 5:
            MeshMapper.SetInput(Mesh)
        else:
            MeshMapper.SetInputData(Mesh)
            
        #Create an actor
        self.MeshActor = vtk.vtkActor() 
        self.MeshActor.SetMapper(MeshMapper)
        #self.MeshActor.GetProperty().EdgeVisibilityOn()
        self.MeshActor.GetProperty().SetColor(colors.GetColor3d("Red"))
       
#self.MeshActor.GetProperty().SetEdgeColor(colors.GetColor3d("Black"))
        
        self.renDesign.AddActor(self.MeshActor)
        
        #Camera Stuff
        camera = vtk.vtkCamera()
        camera.SetPosition(1,1,1000000)
        camera.SetFocalPoint(0,0,0)
            
        self.renDesign.SetActiveCamera(camera)
        self.renDesign.ResetCamera()
        
        self.vtkDesign.SetInteractorStyle(self.Interactor2D())

I would be very appreciated if anyone could help me out! Thanks in advance!



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