[vtkusers] Modifying sphere radius from actor

[Andrea Gavana]

Hi All,

    I am visualizing a bunch of spheres, and depending on some user's
choices, I need to change the radius and the colour of these spheres.
So, instead of removing and re-creating the sphere actor every time I
need to change some sphere property, I thought to use a suggestion
from Amy I found in the archives:

http://www.vtk.org/pipermail/vtkusers/2001-August/057091.html

What I do, is something like this:

sphereMapper = sphereActor.GetMapper()
print "SOURCE:", sphereMapper.GetInput().GetSource()

But this always prints "None" if I execute the attached code (in
Python, using wxVTKRenderWindow). If you run the code, simply press
any key: this activates the OnKeyDown method which tries to extract
the vtkSphereSource from its mapper. Am I missing something? Is it
possible to do what I am asking or I need to re-create every time the
sphere, mapper and actor?

Thank you for your suggestions.

Andrea.


# Begin Code

import wx
import vtk
from vtk.wx.wxVTKRenderWindow import wxVTKRenderWindow
from vtk.util.colors import red, green, blue


class wxVTKRW(wxVTKRenderWindow):

    def __init__(self, parent):

        wxVTKRenderWindow.__init__(self, parent, -1)

        self.ren = vtk.vtkRenderer()
        self.GetRenderWindow().AddRenderer(self.ren)

        centers = [(0, 0, 0), (2, 2, 2), (-3, -3, -3)]
        colours = (red, green, blue)

        for center, colour in zip(centers, colours):

            sphere = vtk.vtkSphereSource()
            sphere.SetCenter(*center)

            sphereMapper = vtk.vtkPolyDataMapper()
            sphereMapper.SetInput(sphere.GetOutput())

            sphereActor = vtk.vtkActor()
            sphereActor.SetMapper(sphereMapper)
            sphereActor.GetProperty().SetColor(colour)

            self.ren.AddActor(sphereActor)

        self.ren.ResetCamera()

        # Store the last actor
        self.lastActor = sphereActor


    def OnKeyDown(self, event):

        # Try to retrieve the sphere source
        # Here is where the problem lies: GetSource() returns None!
        sphereMapper = self.lastActor.GetMapper()
        print "SOURCE:", sphereMapper.GetInput().GetSource()


#--------------------------------------------------------------------
def wxVTKRWExample():
    """Like it says, just a simple example
    """
    # every wx app needs an app
    app = wx.PySimpleApp()

    # create the top-level frame, sizer and wxVTKRWI
    frame = wx.Frame(None, -1, "wxVTKRWI", size=(600, 500))
    frame.CenterOnScreen()

    widget = wxVTKRW(frame)

    # show the window
    frame.Show()

    app.MainLoop()


if __name__ == "__main__":

    wxVTKRWExample()

# End code



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