PSX HW: Severe pixelation across rendered graphics

[davidhedlund]

I did a quick search but couldn't locate an existing report using specific graphics terminology. If a similar report exists, please feel free to link it here and close this issue.

• My GNU/Linux distro is using OpenGL 4.6. "Requirements: OpenGL 3.3 for the opengl renderer" - https://docs.libretro.com/library/beetle_psx_hw/
• In RetroArch both cores are set to "Internal GPU Resolution: 1x (Native)".
• This issue occurs in all games, I'm using the first stage in Wipeout, and Final Fantasy IX, for demonstration.

Beetle PSX HW

Core Version: r24l 9aefd42

I'm experiencing visual artifacts across the entire display. The sky, in particular, exhibits a noticeable pixelation effect in Wipeout, and Final Fantasy IX (just more difficult to observe the pixels). See my screenshot below:

Beetle PSX

No pixelation issues like with Beetle PSX HW. See my screenshot below:

[hizzlekizzle]

Yeah, the OpenGL renderer has a lot of bugs, unfortunately. The Vulkan renderer is much closer to software rendering in reliability.

[davidhedlund]

"Beetle PSX is built without hardware rendering support and lacks enhancements such as texture filtering, PGXP perspective correct texturing, and more. To take advantage of hardware rendering and the various enhancements that come with it, use Beetle PSX HW instead." - https://docs.libretro.com/library/beetle_psx/

Yeah, the OpenGL renderer has a lot of bugs, unfortunately. The Vulkan renderer is much closer to software rendering in reliability.

Thank you! I think that should be added to https://github.com/libretro/docs/blob/master/docs/library/beetle_psx.md -- What do you think about it?

[hizzlekizzle]

Sure, fine by me.

[davidhedlund]

Sure, fine by me.

Thanks:

• Update beetle_psx.md docs#950

[mudl0rd]

Yeah, the OpenGL renderer has a lot of bugs, unfortunately. The Vulkan renderer is much closer to software rendering in reliability.

Wonder how much effort it would take to rewrite it.

[hizzlekizzle]

@mudl0rd I would think that would depend on whether you wanted to fix the OpenGL renderer, backport the Vulkan renderer to OGL or introduce an abstraction so they share the same backend (ala Duck/Swanstation).

[mudl0rd]

Well I saw one major thing missing was any semblance of RTT, which is at least needed for FF battleswirl, MGS, etc.

Currently I am rewriting major config code of WTFweg to now use JSON so its at least more future-proof than INI. But it for me has made massive steps with core compatibility to the point it now runs fine on ARM Linux with GLES2/GLES3. (got it working fine now on Raspberry Pis 4/5) Even with the dear-imgui UI.

So diving back into core development is now 100% feasible for me at least, due to the drastically reduced overhead of using RetroArch for debugging them.

[mudl0rd]

Managed to reproduce the issue at least with one of my fave games: THPS2. Although I'll try some others where its more noticable.

I noticed a VRAM read command was missing from the GL renderer which the VK renderer has - prob related to RTT? glReadPixels with PBOs in the meantime could be used there although that can be slow as heck on older GPUs like AGP. The renderer itself would need to be completely reworked to render to framebuffers instead of the current libretro FB.

[davidhedlund]

Managed to reproduce the issue at least with one of my fave games: THPS2. Although I'll try some others where its more noticable.

I noticed a VRAM read command was missing from the GL renderer which the VK renderer has - prob related to RTT? glReadPixels with PBOs in the meantime could be used there although that can be slow as heck on older GPUs like AGP. The renderer itself would need to be completely reworked to render to framebuffers instead of the current libretro FB.

Thank you so much for taking the time to look into this and for all your hard work! I truly appreciate your efforts. I completely understand that this might be quite a challenge for your team, but I have every confidence in your abilities to tackle it. If there's anything I can do to help along the way, like conducting some simple testing, please don't hesitate to reach out.