[vtkusers] Time support in VTK 5.X

[David C. Thompson]

> I've got a question regarding the VTK 5.X feature set. The VTK FAQ
> states that there will be "time support" as an additional feature. As we
> are mostly working with unsteady data, I'm quite interested in this one,
> so I had a look at the nightly build documentation and some source code
> in order to figure it out. However, I didn't really find much
> information on how it actually works. So I'd like to ask if there is
> some documentation around (which I might have missed) or if someone
> could give a brief explanation...
VTK 5 has low-level support for time series data. There is now a way for
readers to make information about time series available to filters
downstream. If a reader supports multiple time steps (see the Exodus
reader or the VTK XML readers), they will set the
vtkStreamingDemandDrivenPipeline::TIME_STEPS,
vtkDataObject::DATA_TIME_INDEX, and vtkDataObject::DATA_TIME information
keys when you call UpdateInformation on them. These hold a list of
available times (as doubles), the current time step (as a vtkIdType) and
the current time (as a double), respectively. You may then request a
particular time from the pipeline. See
VTK/Graphics/vtkExtractDataOverTime.cxx for an example.

	David