The entire method at use here is essentially not correct. Interpolation should be handled independently of the game timer directly based on the underlying clock, like in ZDoom.
There's interpolation bugs in the Build games that cannot be fixed if totalclock is used for it, but if we use something else we do not need a fractional totalclock.
* Changes performed in 0bd460d9e3 didn't take into account xdimenscale and viewingrangerecip like the days of old and this wasn't picked up in d80a32d379 or d80a32d379, where the applied fixes only appeared to work because they worked for me at 2560x1440p.
The math backend functions have been moved out of Build because they originally have a good license.
# Conflicts:
# source/build/src/mdsprite.cpp
# source/build/src/polymost.cpp
* Output from PrintVis() in 9dfd3ddd02 showed resulting global visibility as 0.078125.
* Following 0bd460d9e3, resulting global visibility shown as 0.041667.
* Scaling g_visibility by (8.f / 15.f) (0.533333) restores resulting global visibility to 0.078125.
This is to allow giving them a texture ID so that they can be used from ZScript which has no access to naked textures.
This also consolidates AnimTexture and VpxTexture.
There are effectively two states - the one in the backend and a local one in the drawer for the render list which is supposed to eliminate some of the more costly repeated calls.
This higher level state was cached globally, which did not work anymore because the real render state could be changed elsewhere without this code realizing it.
All this means that the render list drawer must create a new state cache for each call and also must apply its current pending render state before leaving to ensure that everything is properly reset.
The main reason here is that the scene specific part contains a projection dependent component which would be a problem when transitioning to GZDoom's code. The global viewpoint data already has a field for such a factor so now that gets used.
This also means a significant simplification of the visibility code in Polymost and the removal of several global variables.
Models are inoperable right now anyway so this would never get called, but it does a few things that would cause problems with refactoring the backend code.
