Open pressRtowin opened 1 year ago
There are two major problems with the "SGBC" unofficial extension to the GBC:
While I'm generally open to supporting unofficial extensions (see: the TPP1 mapper), as it stands right now the SGBC extension is no different than supporting ROM hacks that only run on VBA. When and if the situation changes, I will reconsider supporting this extension. Leaving this issue open for future discussion and reference for when the situation changes.
Thanks for the explanation! I'm not so familiar with the technical side of this so this was very insightful & interesting.
For an accuracy-based emulator, supporting this means essentially having two different implementations of the SGB logic, an accurate one for real SGB, and an inaccurate one for SGBC.
Is this what mGBA does? I know mGBA is regarded as a highly accurate GBA emulator, but I don't know much about how accurate their GB/GBC emulation is.
Maybe it's worth noting here too that there appears to be multiple ways this this implemented. I've found some games with added borders don't even display them at all, even when running under SGB (and depend on the unofficial implementations in emulators to display them), while others behave more traditionally and do show a border (but only in SGB mode of course).
I'm not sure what mGBA is actually doing, nor am I sure how accurate SGB emulation is in mGBA. However I did discuss this with BGB's developer Beware. Turns out the first emulator to introduce this thing is NO$GMB (An emulator that got its last update in 2000), and BGB only added this feature for parity. Turns out it was never intended to be used this way, and could break in a future BGB update.
The most hardware-implementable model of SGBC behavior that I know of:
Originally posted here: https://github.com/libretro/SameBoy/issues/87 Adding it here since that repo doesn't seem to have much traffic and other core issues are being reported here anyway.
Current version allows you to force display SGB borders while using GBC colors, however this seems to only work for native SGB-supported games. Certain SGB borders added by ROM hacks (e.g. Kirby's Dream Land 2 DX, Pokémon Crystal Clear) are not detected/enabled as they would be on emulators with full support (I believe mGBA on desktop (but not the core) has this functionality).
See this for some more info: https://www.reddit.com/r/PKMNCrystalClear/comments/o4paxs/how_do_i_play_this_with_the_sgb/