Definitely not something for the renderer to care about directly (ie, at
most, a post-process filter setting or palette update, which is how it
actually is currently).
I think the widespread use of recalc_refdef (and force_fullscreen) was
the result of a rushed merge of the renderer and video code (I do seem
to remember sprinkling them around). This cleans the two out of the
client code.
The more advanced modes are rather broken (continuous spinning), but
they may have been for a while. The bulk of the various changes were due
to renaming viewstate's origin and angles to make their meaning more
explicit.
They've been near-identical for years, now they're only one. It proved
necessary to start merging the HUD code which for now is just a few cvar
declarations (not even init), but that should be a separate set of
commits.
