Anyonw seen Virtual FighterII pattern A corruption before?

sbroumley · Post by **sbroumley** » Fri Mar 27, 2009 1:14 am

I have an issue in my emulator where during gameplay in Virtual FighterII, there are corrupted characters across the first few lines of pattern A.

I'm pretty sure it's not a dma emulation problem, so I might have a mask problem or something wrong in my pattern render code, but for the life of me I can't see anything obvious.

Does anyone know if there is any special pattern map address or tile address masking or something else that I might be missing?

cheers,
Steve.

Snake · Post by **Snake** » Fri Mar 27, 2009 2:25 am

Hey Steve,

It's almost certainly the window. Remember that BGA is masked wherever the window is.

sbroumley · Post by **sbroumley** » Fri Mar 27, 2009 2:52 am

Ah - that totally makes sense.

So if there are non transparent BGA tiles behind a window which contains transparent tiles (ie. has color index zero in them), then BGA will not be visible, but BGB instead? (Assuming BGB is lower pri than BGA).

Snake · Post by **Snake** » Fri Mar 27, 2009 4:41 am

(Assuming BGB is lower pri than BGA).

The window basically replaces BGA, so if the window is transparent, you see BGB through it - regardless of priority.

sbroumley · Post by **sbroumley** » Fri Mar 27, 2009 4:48 am

Got it. And adding correct BGA window masking fixed the problem.

Thanks so much Mr.Snake!