ROM Hack Emulation Yoshi's Island DS on DeSmuME without a blindspot between the screens?

[retrospect]

The viewport of Yoshi's Island DS spans both DS screens, and there is a blindspot between the screens. I think the same is true of Metroid Prime Pinball.

Is there a way to play Yoshi's Island DS with the blindspot filled in? I thought perhaps a ROM hack combined with an emulator that supports filling in the gap?

 

[FAST6191]

Shouldn't need a custom emulator (and the bar can be disabled in options), and indeed can get it working in hardware (might be good for the 2ds).

Somewhere in the game's code is likely a virtual level/space location and the rendering paths take a key from that, in this case presumably adding whatever pixel count is between them compared to the reference.

You would then want to find something on the top screen governed by OAM* for this (BG could also work, but you will likely be back here before long anyway). Whatever is handling that will probably reference the internal location and add a certain amount to it to make it work. Whatever handles the top screen (the DS kind of uses virtual screens http://problemkaputt.de/gbatek.htm#dsvideodisplaysystemblockdiagram ) then presumably adding a certain amount to this to render. Anyway whatever handles the OAM should directly come off of the internal state and the extra tweak to account for the bar/bezel somewhere in that. Might have to go back after sprites are handled to do the same for any OAM but should be easy enough to deal with.

*OAM = object area memory, aka what the sprites are doing.