The model system is rather clunky as it is focused around caching, so
unloading is more of a suggestion than anything, but it was good enough
for testing loading and unloading of IQM models in Vulkan.
This is an extremely extensive patch as it hits every cvar, and every
usage of the cvars. Cvars no longer store the value they control,
instead, they use a cexpr value object to reference the value and
specify the value's type (currently, a null type is used for strings).
Non-string cvars are passed through cexpr, allowing expressions in the
cvars' settings. Also, cvars have returned to an enhanced version of the
original (id quake) registration scheme.
As a minor benefit, relevant code having direct access to the
cvar-controlled variables is probably a slight optimization as it
removed a pointer dereference, and the variables can be located for data
locality.
The static cvar descriptors are made private as an additional safety
layer, though there's nothing stopping external modification via
Cvar_FindVar (which is needed for adding listeners).
While not used yet (partly due to working out the design), cvars can
have a validation function.
Registering a cvar allows a primary listener (and its data) to be
specified: it will always be called first when the cvar is modified. The
combination of proper listeners and direct access to the controlled
variable greatly simplifies the more complex cvar interactions as much
less null checking is required, and there's no need for one cvar's
callback to call another's.
nq-x11 is known to work at least well enough for the demos. More testing
will come.
For now, the functions check for a null hunk pointer and use the global
hunk (initialized via Memory_Init) if necessary. However, Hunk_Init is
available (and used by Memory_Init) to create a hunk from any arbitrary
memory block. So long as that block is 64-byte aligned, allocations
within the hunk will remain 64-byte aligned.
Probably not really necessary, but I think I found a small opportunity
for a buffer overflow in there while I was modifying the code, so this
is probably better anyway.
This fixes a nine year old bug that I discovered only today thanks to
the vulkan renderer. The problem was that when a model had a clear
callback, it was not getting marked as needing to be reloaded, and thus
the model would be "reused" after being trampled on by another model
loading over it.
Also, plug a potential string buffer overflow (strcpy just will not
die!).
Calculate radius for alias models as well as brush.
Culling is no longer optional on alias models (was only ever disabled for viewmodel, which is a lot of extra effort to avoid clip testing 1 thing out of hundreds).
Clip QSG2 scaled alias models with a scaled bbox.
