Transparency of foreground pixels ignored by 3D objects

[snouz]

Background alpha is working correctly between background layers (so I can have soft edges between foreground and scrolling sky for example) but if a layer is on top of a 3D object, it will appear as alpha 1 or 0, never in between.

In the same way anti-aliasing turned out to be an easy feature, maybe this is fixable as well?

[snouz]

A good example here

Alpha on the jar is partially transparent, showing parts of the layer under, but never a 3D object.
If someone is knowledgeable in shaders...

[snouz]

@SamsamTS, Tsuna mentioned that you might know some things about this? This has been itching me since I began working on the mod.

[julianxhokaxhiu]

Hey @snouz Tsuna brought me here. I don't have direct experience with Unity shaders but I might try to help you on the general concept. But before doing that, would you be so kind pointing me where can I find the shader code ( if any around ) and where the shader logic is applied for those specific cases? Thanks :)

[SamsamTS]

@julianxhokaxhiu There is this https://github.com/Albeoris/Memoria/tree/main/Memoria.Patcher/StreamingAssets/Shaders
Unsure if it's of any help.

[Tirlititi]

The shaders used for field objects are mainly:

• PSX/FieldMapActor for the 3D models of the characters,
• PSX/FieldMap_Abr_None for the backgrounds (there are also other Abr shaders used, in particular the FieldMap_Abr_1 for most semi-transparent background layers, like lights, but I think Abr_None is what is involved in all those problems anyway as it originally wasn't meant to handle gradual transparency at all).

Also, it might help to look at my C# code in FieldCreatorScene because it's a relatively compact class that handles the rendering of the fields, with much fewer subtleties than the usual in-game machinery.
In particular, it setups the parameters _OffsetX, _OffsetY, _MatrixRT etc. that are used in the shader's code.

[julianxhokaxhiu]

Thanks a lot for the comments. I'll try to run some investigations here and I'll let you know my findings :) Is this a core issue or happening only with Memoria installed? If the latter, which version can I use to test? latest is good? Also can you please provide a save game where I can repro the scene above?

[snouz]

Thanks for looking at this!
Here are saves for the whole game:
SavedData_ww.zip
You can see this happening all through the game, here's the same example from vanilla:

You can see it happening, because instead of having pixels from the model, we have pixels from the underlayer in green
In fact you can even see the scrolling:


And since there are no grey alpha pixels in vanilla, this is actually a result of the smoothing between black and white alpha pixels that become grey at the display level.

I don't know much about the issue, only that the result of my work is greatly reduced by this limitation. whether I leave grey alpha or limit myself to 2 colors, it will look like shit at the limit with models.

[julianxhokaxhiu]

Thanks a lot @snouz I'll investigate and come back to you

[julianxhokaxhiu]

So I did try to start looking into this, thank you very much for the save game. Have you got experience using RenderDoc on top of FF9? I did try and so far I'm not able to make it work, it seems to not detected the rendering API somehow. I wanted to start from there as it's amazing way to look at what the GPU is doing.

I did try with the vanilla installation, but let me know. I'll try also with Memoria just in case, but this is where I am so far. I'll keep you posted.

[EricHu33]

The jar's render queue is transparent(defined in abr_none shader), while the character is transparent+1

Modifed the queue to transparent+2 will make the transparency work. but probably not intended by default.
Since abr_none are supposed to be the background layer. I guess.

IIRC, the jar itself is not transparent in original game, anyway, at least this provide an option to workaround it.

For anyone want to try themself -> modify "Your FF9 Folder\StreamingAssets\Shaders\PSX\FieldMap_Abr_None.txt"'s transparent queue to transparent+2.

[snouz]

Holy shit that works!

2024-06-09.14-19-55.mp4

2024-06-09.14-26-25.mp4

This fixes so many problems, just changing that!

Thank you so much for looking at it!

[snouz]

It also works with smoke or other effects!
without
with