HLSL does not define roundEven(), only round(). This means that the
output may differ slightly for OpenGL vs Direct3D. However, it ensures
consistency across OpenGL drivers, as round() in GLSL can go either way.
This was breaking Metroid Prime 2: Echoes’s scanner in some rooms, such
as the one in https://fifoci.dolphin-emu.org/dff/mp2-scanner/
It was found on Ivy Bridge on Mesa, the alpha value read back from the
EFB was off-by-4 in multiple objects, which was a conversion error
because int4() is equivalent to floor() and the value wasn’t always
higher.
Improve bookkeeping around formats. Hopefully make code less confusing.
- Rename TlutFormat -> TLUTFormat to follow conventions.
- Use enum classes to prevent using a Texture format where an EFB Copy format
is expected or vice-versa.
- Use common EFBCopyFormat names regardless of depth and YUV configurations.
Currently, we use the alpha channel from the EFB even if the current
format does not include an alpha channel. Now, the alpha channel is set
to 1 if the format does not have an alpha channel, as well as truncating
to 5/6 bits per channel. This matches the EFB-to-texture behavior.
