Code unscale the texture to ease the conversion. Quality is awful (same as before)
but I'm not sure we can support an upscaled texture
Maybe the quality loss is due to the reduction without mipmap
Maybe the best solution will be to add an hack to extract the blue channel
(with texture swizzle), and uses a "full page/screen" spirte instead.
(it would be faster too)
Note: won't be compatible with MSAA (but gl doesn't support it anyway)
// In theory new textures contain invalidated data. Still in theory a new target
// must contains the content of the GS memory.
// In practice, TC will wrongly invalidate some RT. For example due to write on the alpha
// channel but colors is still valid. Unfortunately TC doesn't support the upload of data
// in target.
//
// Cleaning the code here will likely break several games. However it might reduce
// the noise in draw call debugging. It is the main reason to enable it on debug build.
//
// From a performance point of view, it might cost a little on big upscaling
// but normally few RT are miss so it must remain reasonable.
Game can directly uploads a background or the full image in
"CTRC" buffer. Previous code was a full black screen.
It will also avoid various black screen issue in gs dump.
hidden option: preload_frame_with_gs_data
Note: impact on upscaling was not tested and it's likely broken
Improve the rendering in MGS3 (even if the game is still broken
due to others TC issues)
// Typical bug (MGS3 blue cloud):
// 1/ RT used as 32 bits => alpha channel written
// 2/ RT used as 24 bits => no update of alpha channel
// 3/ Lookup of texture that used alpha channel as index, HasSharedBits will return false
// because of the previous draw call format
//
// Solution: consider the RT as 32 bits if the alpha was used in the past
It avoid various upscaling glitches on GS post-processing effect
// 1/ Palette is used to interpret the alpha channel of the RT as an index.
// Star Ocean 3 uses it to emulate a stencil buffer.
// 2/ Z formats are a bad idea to interpolate (discontinuties).
// 3/ 16 bits buffer is used to move data from a channel to another.
//
// I keep linear filtering for standard color even if I'm not sure that it is
// working correctly.
// Indeed, texture is reduced so you need to read all covered pixels (9 in 3x)
// to correctly interpolate the value. Linear interpolation is likely acceptable
// only in 2x scaling
//
// Src texture will still be bilinear interpolated so I'm really not sure
// that we need to do it here too.
//
// Future note: instead to do
// RT 2048x2048 -> T 1024x1024 -> RT 2048x2048
// We can maybe sample directly a bigger texture
// RT 2048x2048 -> T 2048x2048 -> RT 2048x2048
// Pro: better quality. Copy instead of StretchRect (must be faster)
// Cons: consume more memory
//
// In distant future: investigate to reuse the RT directly without any
// copy. Likely a speed boost and memory usage reduction.
It seems to impacts lots of games that still have issue (VP2, MTG3, PoP)
The PSMT32 format is read a PSMT8. I think we need to convert it as PSMT8H (i.e.
unpack it to have only an alpha channel)
GS doesn't supports texture shuffle/swizzle so it is emulated in a
complex way.
The idea is to read/write the 32 bits color format as a 16 bit format.
This way, RG (16 lsb bits) or BA (16 msb bits) can be read or written with
square texture that targets pixels 1-8 or pixels 8-16.
However shuffle is limited. For example you can copy the green channel
to either the alpha channel or another green channel.
Note: Partial masking of channel is not yet implemented
V2: improve logging
V3: better support of green channel in shader
V4: improve detection of destination (issue due to rounding)
When the RT is used as an input texture, we need to rescale it.
Previous behavior was to always uses a linear filtering (more smooth).
Unfortunately it broke some games that expected an exact value like Star Ocean 3
This commit will disable the linear filtering in normal filtering mode (filter = 0
or filter = 2)
This way, shadow of Star Ocean 3 will appear correctly in upscaling (not
100% perfect but can't do better)
Note: SO3 only requires a nearest sampling of the alpha channel but
I don't know the behavior for others games.
Gregory Hainaut