[vtkusers] updating vtkImageData ?

[Jothybasu Selvaraj]

Can you remove

ren.AddActor( self.ia )

from the class and add it after adding the renderer?

Jothy

On Sat, Feb 11, 2012 at 9:07 AM, Anders Wallin
<anders.e.e.wallin at gmail.com>wrote:

> Here is a more realistic example of what I want to do:
> http://pastebin.com/3Wz8C8yC
>
> Now I see different behavior between:
>
> myim = MyImage(ren)  # create vtkImageActor, add it to ren
> renWin.Render()         # when Render() is called here, we don't see
> the results of modify()
> myim.modify()            # this modifies the vtkCharArray of the image
> renWin.Render()
>
> and
>
> myim = MyImage(ren)  # create vtkImageActor, add it to ren
> # without Render() here , the results of modify() are visible
> myim.modify()            # this modifies the vtkCharArray of the image
> renWin.Render()   # now we see a modified image!
>
>
> Confused.
> Anders
>
> On Fri, Feb 10, 2012 at 11:01 PM, David Doria <daviddoria at gmail.com>
> wrote:
> >>
> >> It turns out there is some subtle difference between
> >> vtkRenderer.Render() and vtkRenderWindow.Render()
> >>
> >> This example shows the behavior:
> >> http://pastebin.com/KPFpkCKU
> >> On my machine I see an unmodified image with "renWin.Render()" and a
> >> modified image with "ren.Render()"
> >> I had previously used renWin.Render() in all my vtk code, but I have
> >> always worked with polydata only.
> >
> >
> > Quoting David Gobbi from an old mailing list post that I've used ever
> since:
> >
> > "You should never, ever call renderer->Render().  That method is only
> > meant to be called by the vtkRenderWindow.  The documentation says
> > so quite clearly.  By calling it you are probably causing some timestamps
> > to be set (indicating that all actors in the renderer have rendered), but
> > you
> > aren't actually doing any rendering.  Then, when you call
> > renderWindow->Render() it sees that those timestamps have been updated
> > and thinks that there is nothing to be done."
> >
> > I'm not sure why renderWindow->Render() is not working for you in this
> case.
> > Any Python VTK experts out there?
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-- 
Jothy
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