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, OpenGL and Vulkan renderers are broken as I focused on getting
the software renderer working (which was quite tricky to get right).
This fixes a couple of issues: the segfault when warping the screen (due
to the scene rendering move invalidating the warp buffer), and warp
always having 320x200 resolution. There's still the problem of the
effect being too subtle at high resolution, but that's just a matter of
updating the tables and tweaking the code in D_WarpScreen.
Another issue is the Draw functions should probably write directly to
the main frame buffer or even one passed in as a parameter. This would
remove the need for binding the main buffer at the beginning and end of
the frame.
I'd been considering it for a while, but in the end, all the issues it
presented made me decide it wasn't worth merging and was never really
worth keeping: it was a neat proof of concept but of little actual use,
especially now everyone either has an OK GPU or would want to stick to
8-bit rendering anyway (sorry L-Havoc).
However, both it and my merge work are preserved in git history :)
16 and 32 bit rendering are disabled at the moment because there's a
weird segfault I need to fix, but the 8-bit dynamic lights are doing
weird things (for x11, too) when updating the light maps.
It turns out the dd and dib "driver" code is very specific to the
software renderer. This does not fix the segfault on changing video
mode, but I do know where the problem lies: the window is being
destroyed and recreated without recreating the buffers. I suspect a
clean solution to this will allow for window resizing in X as well.
