Yes Andras, you are right, but all that stuff is a matter of “time to spend”.
Of course you can develop your own Actor / Mapper / Shader / … but this cannot be done without a profound and clear understanding of VTK “arcanes” and “ways” to drive the graphic subsystem.
And this can be a real time sink.
On the other hand, you can search for the easiest way to deal with “standard” VTK behaviors, and find some tricks to make things append the way you want.
Obviously, VTK has been tailored to deal with a few number (order of magnitude 10) of complex geometries.
I’m repeating myself, but displaying a huge number (1k, 10k, 100k …) of simple geometries, each having its own behavior as far as color/picking/visibility/… and achieving good perfs (30 fps +) at the same time, is rather tricky.