This fixes severe image flickering in some cutscenes of Twin Snakes. The game appears to sometimes load a previously made XFB copy as a texture before it is actually rendered to the screen, which we took as an invitation to invalidate the XFB copy.
We want this setting to invalidate the cache because it may affect the appearance of textures in the rendered scene, therefore one would expect changing it while the game is running to have the expected effect immediately.
This no longer converts from sRGB to linear for the reference mip
downsample - even if the original mipmap creation tool used an sRGB
colorspace (which isn't really guaranteed, and may even change per
game), this is a "fast" heuristic that's only an estimate anyway.
The average diff is also now stored in a u64, avoiding floating point
calculations in the per-pixel hot loop.
This should speed up the detection significantly, hopefully fixing
jank when loading in new textures.
Using 8-bit integer math here lead to precision loss for depth copies,
which broke various effects in games, e.g. lens flare in MK:DD.
It's unlikely the console implements this as a floating-point multiply
(fixed-point perhaps), but since we have the float round trip in our
EFB2RAM shaders anyway, it's not going to make things any worse. If we
do rewrite our shaders to use integer math completely, then it might be
worth switching this conversion back to integers.
However, the range of the values (format) should be known, or we should
expand all values out to 24-bits first.
Hopefully this better matches the user's view of a texture - as large changes in
colour should be weighted higher than lots of very small changes
Note: This likely invalidates the current heuristic threshold default
Also makes y_scale a dynamic parameter for EFB copies, as it doesn't
make sense to keep it as part of the uid, otherwise we're generating
redundant shaders.
Lowest hanging fruit I could find with a profiler.
Not sure this stuff actually needs to be done, but assuming it is, why
not do it quickly? 10x faster, goes from 1% CPU to 0.09%.
The option is named DisableCopyToVRAM under the Hacks section in
GFX.ini. It is intentionally not exposed to the GUI, as users should not
need to use it under normal circumstances. The main use is debugging
issues in the EFB-to-RAM shaders.
