[vtkusers] Offscreen plotting

[Jordi Gutiérrez Hermoso]

I'm on Debian. I understand VTK has to be compiled in a special way in
order for offscreen plotting to work. I want to make a bunch of images
and later stitch them together int a movie, and offscreen plotting
seems the easiest way to do so. I don't believe the VTK Debian
maintainer compiles VTK with offscreen support. How can I check, and
how can I compile it myself to do this?