Making mappings for S2 2-player?

I've added knuckles to Sonic 2s' 2-player mode. He works fine, for the most part, but he can't display properly (he appears as an odd mix of straight colored lines and gibbrish). How would I fix his mappings/artwork so that he appears like he should, 2-player mode or not?

 

Doesn't SonMapEd have an option to make mappings 2 player compatible? Or maybe it was LOst Library.

 

I tried writing a program for it, but... it doesn't work very efficiently, it adds a lot of extra blank tiles, causes Knuckles' art to overflow the alloted space, and some frames are a bit glitched.

The problem with 2P mode is that you can only use sprite pieces with heights that are a multiple of 2. Sonic and Tails' sprites obey this restriction, but Knuckles' don't.

 

Ugh, that sounds like a painfully obnoxious task to do by hand. Perhaps you could make the program check if it's placing a blank tile and reuse the same blank tile...

 

You're missing the point. The blank tiles are there to make all the sprite pieces have an even height. I can't reuse the ones that are there because they have to be with the tiles for the sprite piece I'm extending.

The other option is to turn the sprite mapping into an image, and then turn the image back into a sprite mapping using only even height pieces, but I don't know what the best way to do that would be.

 

Wow, that sounds messy. I can imagine the game using a lot more art space if you converted it into an image and back (unless the mappings dynamically shifted with the image, but that sounds even messier. I guess I can have Sonic play instead of knuckles...

 

So that's why Sonic's art has so many blank tiles, was wondering about this. 

 

You could just have separate 2P mappings...but then that would mean mapping every sprite over from scratch.

 

Having separate mappings for 2P would be pointless too. 2P-compatible mappings are perfectly usable in 1P mode.

 

2P uses 8x16 instead of 16x16 iirc. I'm sure it's usable but with something that won't normally fit, having separate mappings is doable....or you could just do what S3 does and have mini sprites :v

 

I know this is somewhat unrelated to the issue at hand, but I always thought that S2 would benefit from having the entire 2P revamped to behave like in S3. Specially designed sprites and reworked art for the cause as opposed to interlaced art would look so much better, as I always felt the interlaced art looked a bit disjointed, if you get what  I mean. Some of the art when compressed in such a way loses so much detail that it actually looks horrible. S3 handled it very well, and I'm guessing that sacrifice on detail was the reason for the change in direction. If someone was to overhaul the 2P to behave like S3 then that is a hack I would be very interested in seeing. I would love to look into it myself but unfortunately I just haven't got the time available anymore to really dedicate any to hacking, except for the occasional disassembly work.

 

StephenUK, that would be amazing. Someone should make an open source project around this, so that other hackers can work with 2P mode, instead of consistently having to remove it from their hacks.

 

The way Fusion renders interlaced mode in 2x scale looks really nice (though in the emulator itself, it's double the width):



Technically, Regen and Genesis Plus GX do it more accurately, where the lines flicker between even and odd every frame. Gens does it the worst, just displaying only odd lines.