[vtkusers] update confusion

[Sebastien BARRE]

At 30/10/00 16:35, Sven wrote:

>I am totally confused by how update works.
>It seems when I display a slice of an image volume in a TkImageViewerWidget
>every time I go to a different slice the imaging chain executes again!

sure, as it has to seek for the slice.

>Sometimes, it doesn't execute at all and I receive a "Pixel .. not in memory
>error!

you may be out of bounds/extent.

>How can I have the chain execute one for the whole volume independent
>on what's on the screen?

if your object is named "reader", then :
         reader UpdateWholeExtent
will do the trick by reading the whole stuff in memory.
if you use vtkImageReslice to display a slice from a volume, you do not 
need that, but if you use two different vtkImageReslice (or objects) on the 
same reader, then use UpdateWholeExtent once.