Semi-Transparent texture replacement issues

[Sandvichero]

Description

When using custom texture replacement semi-transparency is ignored, in this case opaque whites become solid whites.

Expected behavior

For the lettering in my custom font to maintain its original smoothness(Semi-Transparency)

-Original Custom Texture-

Actual behavior

Smoothness(Semi-Transparency) is ignored in game creating rough lettering

-File when Injected into the game-

Steps to reproduce the bug

1. Edit a dumped texture in this case a font to something that uses semi-transparency
2. Inject texture into game.

Version/Commit

-Beetle PSX HW: 0.9.44.1 bf5d7f8

Environment information

• OS: Windows 10.0.18363 Build 18363
• GPU: Nvidia RTX 2070

[xzn]

Correct me if I'm wrong:

Beetle psx textures have only 1-bit alpha: for each pixel it's either opaque or fully transparent. Semi-transparency is archived by adding a per-vertex color component (which contains alpha) and has nothing to do with the textures themselves.

If you want the behavior you described the Vulkan backend will have to be updated to have essentially a new features. Maybe change the issue to a feature request? The PNG format does support alpha channel so this could be useful.

OTOH I'm surprised that the text shows up as opaque white instead of having a grey border. What gives??

[stoofin]

IIRC the vulkan renderer uses the depth buffer in opaque render passes as a substitute for drawing order, so I didn't put in alpha blending because 1) I'd have to remove that feature and already felt bad enough about defacing the vulkan renderer the way I did and 2) I couldn't think of a nice way to represent both the semi-transparency bit and alpha in the texture without making upscaling/editing a lot more finicky for me than it already was and introducing a lot more weird edge cases in filtering.

I think since ps1 games already sort their polygons anyway due to lack of z buffer it'd be possible to add that kind of alpha blending, but I'm not convinced my method was the best way to do this in general so putting more work into it seemed iffy.