Regarding 480i as seen in Sonic 2's 2-player mode . . .

[Kirk_Johnston]

I'm curious, does anyone know if this is done the same way as the 480i mode on SNES when running in background modes 0-4 (and 7) or the 480i mode on SNES when running in backgrounds modes 5-6 (the interlacing methods are slightly different depending on which one it is)?

[Kirk_Johnston]

Does anyone know about this?

[jeffythedragonslayer]

Do you have a link to a video?

[Kirk_Johnston]

5 hours ago, jeffythedragonslayer said:

Do you have a link to a video?

Which part, footage of Sonic's two player mode or footage of how those modes work on SNES, or soemthing else?

 

Here's something of both:

 

Hopefully that helps.

Edited January 11, 2023 by Kirk_Johnston

[jeffythedragonslayer]

I thought that Retro Game Mechanics video was hard to follow.  For example, I really don't see why the term "pixel" is confusing.  So what if the size of a pixel changes?

 

For the record, I also don't like the idea of "half-dots" in psuedo-horizontal 512 mode, because I like to think of a pixel as the fundamental picture unit.  Once I can divide it in half, I consider it two pixels at that point.

I think this sentence at 1:52 is poorly worded:

 

Quote

But in reality, only half of it is drawn every frame.

 

I think it should be:

Quote

But in reality, only half of it is drawn every field.

Because in interlacing, a frame is made up of two consecutive fields.

 

Anyway, back to the topic at hand.  Basically, if I understand your question correctly it boils down to, does the Sega Genesis, when playing Sonic the Hedgehog 2:

 

1) Draw the exact same image twice, once for the first interlacing field and again for the second interlacing field, such that every pixel has a same-color pixel neighbor either directly above or below it, or

2) Alternate between drawing the odd scanlines of the image in one interlacing field and then even scanlines of the image in the other interlacing field - where each pixel may have different colored neighbors all around.

 

Is my understanding of your question correct?  If so, perhaps you could post it on a Sega Genesis forum as I have phrased it above.

 

I could kind of understand where people are coming from if they were to talk about half-dots in situation #1 above, because the same color appears twice on two consecutive fields.

[Kirk_Johnston]

Yeah, I asked in SpritesMind, and it seems it's doing it as per 2).

 

PS. Personally, even if his stuff isn't 100% perfect and there's a few minor errors, I still found the RetroGameMechanicsExplained videos the most comprehensive and best resource I've ever come across explaining SNES, as least from the position of someone who's a bit less programmer-minded and more of a "layman" as such, and just wants to learn about all of these SNES features and capabilities from a slightly higher-level perspective.

Edited January 12, 2023 by Kirk_Johnston

[Kirk_Johnston]

Basically, unless I'm missing something, using one of these two interlaced modes as described in the Genesis developer's manual on pages 69 and 70, you either get pseudo double the vertical resolution where really it's just the same image shifting slightly on each field for a slightly flickery "higher-res" optical effect, or proper double the vertical resolution but where it's visually squished vertically [by default]:

 

https://fabiensanglard.net/another_world_polygons_Genesis/GenesisSoftwareManual.pdf

 

The interlace normal resolution on Genesis is basically done the same way as the interlacing is handled in Modes 1-4 and 7 on SNES, and the interlace double resolution mode on Genesis is basically done the same way as the interlacing is handled on Modes 5 and 6 on SNES.

 

How it's done in Modes 1-4 and 7 on SNES:

 

How it's done in Modes 5 and 6 on SNES:

 

And the main difference here is that the SNES has the additional 512 horizontal resolution in Modes 5 and 6 that works in conjunction with the equivalent of interlace double resolution mode there to more easily allow for the output of visuals that are not squished in one direction. The SNES actually changes the standard 8x8 tile size to 16x8 in this mode, so it appears to look 8x8 in 512 mode, and it also as has a 16x16 tile option in every background mode, which is not changed in this mode, thus appearing to look either 8x16 in 512 mode or 8x8 in 512x448 mode. Also, the SNES drops to two background layers with one of them in 2bpp in Mode 5 and only has one background in Mode 6 to presumably allow you get roughly around the same amount of unique tiles as the other background modes at basically the same cost in VRAM.

 

Sonic 2's two-player mode runs in interlace double resolution mode.

Edited January 12, 2023 by Kirk_Johnston

[jeffythedragonslayer]

I think they typo'd "file" when they meant to write "field" in that Genesis manual on page 69.

 

I like the terms interlace double resolution and interlace normal resolution... did you see them somewhere in the Genesis manual?

 

Another thought I had the other day was, you can kind of think of the SNES background modes as becoming more sophisticated by increasing number.  Mode 0 is the most basic mode, only being 2bpp; Modes 5&6 are the hires modes; all the way to the almighty Mode 7 and its 3d glory.

Edited January 13, 2023 by jeffythedragonslayer

[Kirk_Johnston]

5 hours ago, jeffythedragonslayer said:

I think they typo'd "file" when they meant to write "field" in that Genesis manual on page 69.

 

I like the terms interlace double resolution and interlace normal resolution... did you see them somewhere in the Genesis manual?

 

Another thought I had the other day was, you can kind of think of the SNES background modes as becoming more sophisticated by increasing number.  Mode 0 is the most basic mode, only being 2bpp; Modes 5&6 are the hires modes; all the way to the almighty Mode 7 and its 3d glory.

Ha, yeah, I think you're right regarding the typo.

 

The terms interlace double resolution and interlace normal resolution where how the person in AtariAge described it, so I just went with that here too.

 

Yeah, that's generally how the background modes are thought of, which makes total sense. Although, because I like the sheer parallax potential of Mode 0 and indeed think many of the background modes have been largely under-exploited, I like to think you could also just as easily look at things in reverse too, where the lower mode number the more background layers and therefore parallax potential plus unique tiles you get.

 

Really, I think the actual truth of it is that each mode has its strengths and weakness, and the best way to think of them is to consider what one is going to give you what you need in whatever particular situation. So, Mode 1 is like the jack of all trades and most useful in most typical scenarios, Mode 0 gives you huge parallax potential (beyond any other consoles of the time), Mode 3 opens you up to really high-colour images (maybe for cutscenes), Mode 5 allows some cool high-res stuff (might be useful for text adventure and actually something more exciting than that), and Mode 7 is the one that does all the faux 3D (which, while limited to a single background, is for showing off).

 

This is one of the reasons why I say the SNES still holds a whole load of untapped potential. It's not particularly exciting when it comes to sprites, although still absolutely up to par for the time there, but it's just a treasure trove of options when it comes to the background capabilities.

Edited January 13, 2023 by Kirk_Johnston