GS/DX12/VK: Shader based sprite round/clamp/align for upscaling. (WIP)

[TJnotJT]

Status: Currently a WIP for testing so bug reports are appreciated.

Description of Changes

• Add shader based sprite round/clamp/align for upscaling
• Committed on top of GS: Accurate UV rounding for axis-aligned prims. #14078.
• Currently disables other sprite upscaling fixes to make testing easier.
• Not implemented yet for DX11/OGL, which might not work correctly in this build.

Rationale behind Changes

• Helps to prevent visual glitches in upscaling such as UI/font lines and misalignments.
• Helps things fixed by GS: Accurate UV rounding for axis-aligned prims. #14078 with upscaling also.

Details/Config

Implements the following sprite adjustments:

• Alignment: aligns sprite to native coordinates.
• Rounding: downscales texture coordinates to native resolution, does rounding, and then upscales again. May make some textures look blockier.
• Clamping: clamp texture coordinates to maximum range used at native resolution. May clip some texture if they are also clipped at native.

Adds the following INI settings:

[EmuCore/GS]
AccurateUVRounding = 1
SpriteAlign = 2

• AccurateUVRounding:
  • 0 (off)
  • 1 (on)
  • Default in this build is 1.
• SpriteAlign:
  • 0 (off)
  • 1 (align)
  • 2 (align + clamp)
  • Default in this build is 2.

Limitations

• AccurateUVRounding = 1 may cause some texture to lose resolution. Can sometimes be improved with AccurateUVRounding = 0 and keeping SpriteAlign = 2 to prevent lines.
• SpriteAlign = 2 (clamp+align) can sometimes cause seams. Can sometimes be improved with SpriteAlign = 1 (align only).
• Anything that is broken at native will likely be broken with this PR (e.g. fonts that appear clipped at native such Armored Core HUD).
• May have seams in games that do copies with small sprites split over multiple draws (e.g. Tekken Tag Tournament and Mobile Suit Gundam).
• May have misaligned UI element if the game uses a mix of right triangles and other geometry (e.g. Gran Turismo 4).
• Todo: Does not yet handle right triangles that rotate textures 90 degrees (e.g. Everybody's Tennis UI).
• Todo: Bilinear filtering with upscaling is currently broken. This causes bugs in games that use bilinear for antialiasing like Dragon Quest VIII and Jak and Daxter TPL.
• Todo: Mainly tested on 2x upscaling, results may differ on higher upscales.

Suggested Testing Steps

Use DX12 or VK with 2x or higher upscaling. The following settings are enabled by default:

[EmuCore/GS]
AccurateUVRounding = 1 # on
SpriteAlign = 2 # align+clamp

The following may be better in some cases at reducing lines while keeping good UI quality:

[EmuCore/GS]
AccurateUVRounding = 0 # off
SpriteAlign = 2 # align+clamp

The followin may be better in some caes (e.g. some Tekken games) where there are seams in the frame:

[EmuCore/GS]
AccurateUVRounding = 1 # on
SpriteAlign = 1 # align

Did you use AI to help find, test, or implement this issue or feature?

To ask questions about GLSL/HLSL and other topics. Also see the answer here: #14078.

Comparisons (fixes)

bge.gs.xz (needs autoflush enabled)

Master 2x

PR 2x

---

Yu-Gi-Oh! The Duelists of the Roses_SLUS-20515_20250511091941.gs.xz (font lines)

Master 2x

PR 2x (some font clipping as with native)

---

Dynasty_Warriors_5_-_Xtreme_Legends_floor.gs.xz (lines in UI and floor)

Master 2x

PR 2x

---

Street Fighter III - 3rd Strike_SLPM-65621_20220827100351.gs.xz (lines)

Master 2x

PR 2x

---

Psychonauts_SLUS-21120_20240704234653.gs.xz (bloom on signs)

Master 2x

PR 2x

---

Armored.core.2.Arena.text.gs.xz (font lines)

Master 2x

PR 2x

---

Astro Boy_SLUS-20867_20260131162220.gs (UI lines)

Master 2x

PR 2x

Astro Boy_SLUS-20867_20260131162220.zip

---

Disney G-Force_SLUS-21891_20260131161732.gs (font lines)

Master 2x

PR 2x

Disney G-Force_SLUS-21891_20260131161732.zip

---

hack_Infection_3x.gs (font lines)

Master 2x

PR 2x (some blocky font like native)

hack_Infection_3x.zip

Comparisons (breaks)

Dragon Quest VIII - Journey of the Cursed King_SLES-53974_20240619012551.gs.xz (broken bilinear antialias, see face)

Master 2x

PR 2x

---

Jak_and_Daxter_-_The_Precursor_Legacy_SCES-50361.gs.xz (broken bilinear antialias, fuzzy)

Master 2x

PR 2x

---

Pac-Man_World_2_SLUS-20224_20220816132032.gs.xz (blocky UI/balls; a bit better with rounding disabled)

Master 2x

PR 2x

PR 2x (AccurateUVRounding = 0, SpriteAlign = 2)

---

Armored_Core_2_SLUS-20014_20240407012352.gs.xz (fixes lines but lowers UI quality to native; a bit better with rounding disabled)

Master 2x

PR 2x

PR 2x (AccurateUVRounding = 0, SpriteAlign = 2)

[Felipefpl]

Hi, Good to see Street Fighter 3 fixed. Thanks for that. 👍 Do you know if this fixes the black lines of HP/MP bars of Shining Force EXA? This is a bug that happens only when we upscale the game.

[TJnotJT]

Do you know if this fixes the black lines of HP/MP bars of Shining Force EXA? This is a bug that happens only when we upscale the game.

Yes, that screen is fixed at 2x (edit: there's a line next to "S" in the bottom-right that's also in SW so will need to be checked on a PS2):

However, it causes a line in another UI (also in master/PR SW) so it needs to be checked on a PS2:

Master 1x:

PR 1x (see above the "Piece"):

Edit: Looks like both lines occur on a PS2 also:

Shining Force EXA_SLUS-21567_20240617191607.gs.xz.zip
Shining Force EXA_SLUS-21567_20240617191638.gs.xz.zip

[Felipefpl]

@TJnotJT - NICE! Thanks for the info. :)

[matitone71]

Fixes all the arcade Tekken games on Tekken 5:
(Screenshots all taken at 2x resolution with the default PR settings)

Master:

PR:

Master:

PR:

Master:

PR:

Tekken 4 has its UI fixed, but it has some weird small lines going across the screen now

Master:

PR:

[TJnotJT]

Tekken 4 has its UI fixed, but it has some weird small lines going across the screen now

Thanks for catching that. I did some quick testing with a Tekken Tag dump, and setting SpriteAlign = 1 (align without clamp) seems to remove the seams. It may bring back the UI lines, though, so if you happen to have a dump of that specific scene, that would be helpful for further testing.

[matitone71]

SpriteAlign set to 1 does indeed remove the seams and the UI is still fixed, it's perfect now.

[Shifroval]

I can report that at least menu part of the bug was fixed, thank you, @TJnotJT !

But as I reported earlier in another pr, hub map, all icons and menu boxes are now all shifted to the right. Text looks a bit off too. Also all the circle borders around the icons are uneven, but they are not shifted. And my eyes are not decieving me here, if you fast scroll between two images in a viewer, you can see how the whole screen has a shift. I tried to reproduce the scene as close as I can in two different builds.

Master

PR

Actually AccurateUVRounding = 0 fixes the shift, but the fonts are off again and now icons shift is inverted. On the bright side, menu lines are still fixed

I've made two dumps of this frame (all with 3x scaling as before), first with default settings
.hack Infection Part 1_SLUS-20267_20260326103046.gs.zip

And this with rounding set to 0
.hack Infection Part 1_SLUS-20267_20260326110808.gs.zip

Hope you can get to the bottom of it.

Edit.
Sprite align 0 or 1 introduces lines on almost all sprites.

[TJnotJT]

@Shifroval Thanks for testing and the feedback. The blocky text and alignment issues are a limitation of this PR, as it relies on native alignment/rounding as a guide. Here’s a frame captured on a PS2, showing similar issues:

We could try heuristics or additional settings to mitigate this, but that may be tricky and might fix some cases while breaking others. It’s something we could explore in the future.

[Shifroval]

Ok, I finally got my old ps2 up and running (SCPH-90008 with opl running games over ethernet), I've no capture card, but I fiddled with gsm settings to make image more or less acceptable to take a photo.
I can at last confirm that at least in my case the real ps2 indeed renders the map like this, with eneven edges and uncentered icons. I checked text boxes too and they are also rendered like with your fix applied. Sure, the game was developed on crts and for crts, so many artifacts we see now where masked by the shortcomings of the technology.

So I guess that concludes the case? The only thing that I still can't be certain about is the image shift, is it a byproduct of the fix, or the whole time pcsx2 was rendering the image wrong? I know you can run gs dumps on your ps2, @TJnotJT, could you please capture how they look for you? You see the shift too, right?
Here's the dump from master (the ones above are from this pr)
.hack Infection Part 1_SLUS-20267_20260327192115.gs.zip

Also I faintly remember there was a pr many years ago that fixed map rendering glitch, I believe it also 'fixed' how ps2 was rendering it, making it more geometrically accurate, but apparently less hardware accurate. For instance the screenshots of old lparchive playthrough have uneven edges, but centered icons, but that's from 2011
https://lparchive.org/hack-Series/Update%2002/

If the whole purpose of pcsx2 is to be as accurate to the real hardware as possible, then your fix actually nailed it down perfectly. But maybe the shift is still wrong.

[TJnotJT]

The only thing that I still can't be certain about is the image shift, is it a byproduct of the fix, or the whole time pcsx2 was rendering the image wrong?

In many cases, the fix applied in #14078 results in a 1-pixel texture shift due to how the GS rounds UV coordinates.

Here are the frames for comparison, the map does appear to be shifted between PS2/PR and master.

PS2

PR

Master

[Shifroval]

In many cases, the fix applied in #14078 results in a 1-pixel texture shift due to how the GS rounds UV coordinates.

Thank you for testing this, I can see that menu sprites are shifted, yes (and I think that's expected, as you say texture shift), but I'm more concerned about 3d geometry or viewport space (not sure how to call it here) shift. In all cases I never touched the camera and only paused the game at the exact same spot, you can see that 2 screens from PR have identical street and city geometry layout and position of the portal model on the screen (ignore npcs, they're always running around), but Master's viewport is slightly shifted to the left. I can reproduce these shots easily and in all cases can see it. On your frames I can only see sprite shift.
I know it's minor, but I'm concerned if it's something bad or unwanted. Open my first two screenshots in your favourite image viewer and scroll between them until you notice it. I don't know if it's something trivial or expected for you as a developer, but as a player and a tester I see the difference. I don't have a capture card, so can't do a direct PR to PS2 comparison, thus I can only judge by how pcsx2 renders the scene.

[TJnotJT]

@Shifroval Yes, there is a viewport shift as well, the PR applies a native half-pixel offset to all geometry.

The idea is to align upscaled pixels with the native pixel grid so they map cleanly (e.g., at 2x, each native pixel corresponds to a 2×2 block; at 3x, 3×3, etc.). This makes it easier to snap sprites to native coordinates and do rounding, since the mapping between upscaled and native pixels is unambiguous.

There are definitely some downsides as noted in the OP, but I’m not entirely sure which of them are specifically due to the half-pixel offset versus the overall alignment/rounding approach.