[vtkusers] RequestInformation, RequestData and vtk filter, help needed

[Markus R]

Hi,

I am trying to write a filter in vtk (also to be imported in ParaView later). But I find the documentation not so good. I have a good idea what I need to do, but the functions RequestData, RequestInformation, RequestUpdateExtent, and a few others are confusing me. It seems to me these functions are automatically called for when you apply a filter in the pipeline, but in what order? And what code should they contain?

I have looked at the already many existing filters for vtk (and also paraview) and sometimes they use RequestInformation, but not always. RequestData seems always be implemented. Well, I am indeed lost without documentation what these functions really should do, what code they should contain, and when I should use them.

What I basically want to do for my filter is to take an unstructured grid as input, then perform my algorithm, and have as output an image. Could someone kind explain a few lines about the functions mentioned above, or link me to any documentation that explains their use and purpose? 

Regards, Markus

_________________________________________________________________
Express yourself instantly with MSN Messenger! Download today it's FREE!
http://messenger.msn.click-url.com/go/onm00200471ave/direct/01/