Most static opaque status bars are on BG3, but why?

[SNES AYE]

I've noticed that in many SNES games, a static opaque status bar typically utilises the 2bpp BG3 layer instead of part of one of the 4bpp layers.

I understand that BG3 can be easily brought in front of all other layers, and if there's nothing else using parts of BG3, it's straightforward to keep it static for an opaque status bar. However, is it really that challenging to use part of a 4bpp layer, add an instruction to keep that section static, as many NES games do with their single background layer for the status bar area, and then enjoy a status bar in full colour rather than the limited "NES" colour palette?

Given that I'm talking about an opaque status bar, where there's no need to display anything behind it, is there any truly legitimate reason not to opt for a 4bpp status bar on part of BG1 or BG2 that doesn't scroll, instead of using a 2bpp status bar on BG3?

[stan423321]

The full-on status bar was probably less decorative and more functional, and 2bpp tiles took less VRAM.

[SNES AYE]

The full-on status bar was probably less decorative and more functional, and 2bpp tiles took less VRAM.

That's an interesting consideration. Given that all the other systems of that generation did their opaque status bars with 4bpp tiles and I think within a similar VRAM size without any major issues that I'm aware of, I'd assume there's no real reason to worry about the SNES running out of VRAM any quicker under similar conditions. Would you say that, as long as the rest of the background and sprite tiles are managed properly, it's not really an issue to opt for a nice 4bpp status bar then, at least for any modern SNES title aiming to look as attractive as possible?

[Bregalad]

I think the SNES has more feature so each game did their own thing like they wanted. In the early SNES days, the ability to make (semi-)transparent status bars was new so almost everybody went full on it and naturally used BG3 for that.

If you're going to have an opaque status bar, using only BG3 (instead of IRQ/HDMA to change the scrolling on level layers) is a poor choice, because you "loose" one colour compared to the NES equivalent, as a tranparent color would show the level behind the status bar. So you only have 3 solid colors per tile to work with.

That being said there's the advantage of having tiles eating up only 16 bytes of VRAM per 8x8 tile instead of 32, and the advantage to not have to use HDMA or IRQ to change the scrolling and possibily the tilemap base adress.

If there's a specific game you have in mind we might investigate why they did this that way.

[SNES AYE]

I think the SNES has more feature so each game did their own thing like they wanted. In the early SNES days, the ability to make (semi-)transparent status bars was new so almost everybody went full on it and naturally used BG3 for that.

If you're going to have an opaque status bar, using only BG3 (instead of IRQ/HDMA to change the scrolling on level layers) is a poor choice, because you "loose" one colour compared to the NES equivalent, as a tranparent color would show the level behind the status bar. So you only have 3 solid colors per tile to work with.

That being said there's the advantage of having tiles eating up only 16 bytes of VRAM per 8x8 tile instead of 32, and the advantage to not have to use HDMA or IRQ to change the scrolling and possibily the tilemap base adress.

If there's a specific game you have in mind we might investigate why they did this that way.

There wasn't a specific game in my mind when I posted; it was just something that I was curious about. However, I was looking at Ghost Chaser Densei the other day, and I wasn't originally sure if it was using BG3 with some sprites for the full-colour headshots or one of the other backgrounds while keeping the status bar colours quite simple as a deliberate design choice. That's probably why the status bar stuff was still on my mind. I think about this quite a lot anyway, because many SNES games use BG3 for partly full-transparent overlapping status bars, and I'm always considering how they did or could make the most of the more limited colour palette there or if they could have actually used part of one of the 4bpp layers in many cases.

[Oziphantom]

It's to cover the sprites. While you can easily just cut the scroll of the background, its impossible to cover over the sprites. You could use windows as well though to be fair but that would use a HDMA channel.

Also if you have vertical scrolling you would really limit how far ahead in the buffer you can move before you have to replot the whole screen and shift it back down. While using BG3 lets you just wrap BG1 and 2 as per normal for scrolling.

[SNES AYE]

It's to cover the sprites. While you can easily just cut the scroll of the background, its impossible to cover over the sprites. You could use windows as well though to be fair but that would use a HDMA channel.

Also if you have vertical scrolling you would really limit how far ahead in the buffer you can move before you have to replot the whole screen and shift it back down. While using BG3 lets you just wrap BG1 and 2 as per normal for scrolling.

Yes, those seem like some good reasons why opting for BG3 would genuinely save some time and hassle.

So, would these be some rare examples where they've managed to use the 4bpp opaque status bar and overcome most of those potential sticking points:

gameplay of Do-Re-Mi Fantasy

gameplay of Kirby Super Star

gameplay of R-Type III

Or are they perhaps using some other trick here to achieve what looks like a higher colour status bar, but it's actually still using BG3?

[creaothceann]

You can just load these in Mesen and open the tilemap viewer which shows you the backgrounds, etc...

[Bregalad]

It's to cover the sprites. While you can easily just cut the scroll of the background, its impossible to cover over the sprites. You could use windows as well though to be fair but that would use a HDMA channel.

BG0 with frontmost priority would also cover the sprites, and also there's the possibility to have other sprites in front of it if required (a possibility that doesn't exist with BG2).

Also if you have vertical scrolling you would really limit how far ahead in the buffer you can move before you have to replot the whole screen and shift it back down. While using BG3 lets you just wrap BG1 and 2 as per normal for scrolling.

This is a non-issue on SNES because you can change the tilemap's base adress easily with HDMA or an IRQ. Similar to what you would do with NES' single-screen mirroring, but while allowing any tilemap size for the level.

So really, the only advantage of using BG3 is to have smaller VRAM footprint for tile definition.

Or are they perhaps using some other trick here to achieve what looks like a higher colour status bar, but it's actually still using BG3?

The obvious trick is to use overlaid sprites where the extra colors are needed "show through" transparent colour on BG3.

[SNES AYE]

You can just load these in Mesen and open the tilemap viewer which shows you the backgrounds, etc...

I had a look, but half of them have corrupt tilemaps or something, so it's hard for me to tell. The Do-Re-Mi game looks like it's using one of the 4bpp layers, though, so it's cool to see a working example of it in action. Given I'm not seeing any major problems there, I'm surprised basically every SNES game with an opaque status bar didn't go this route, purely for the extra visual flair it can allow. I can definitely understand opting for BG3 when it's for an overlaid status bar where you want to see most of the level behind it, though. However, even then, I think there are times when parts of the background could be shifted around, and then a section of one of the 4bpp layers used for a nice 4bpp overlaid status bar that also shows parts of the level behind it.

The obvious trick is to use overlaid sprites where the extra colors are needed "show through" transparent colour on BG3.

I think that's a nice way of balancing things out, so you get the benefit of using the VRAM-saving BG3 for either an opaque status bar or the overlaid status bar with some see-through sections, alongside some higher-colour parts that give the whole status bar a nice visual appeal overall. I noticed that Ghost Chaser Densei actually uses a combination of BG3 for an opaque 2bpp status bar, with one of the other layers overlaid on top to create some nice 4bpp headshots.

[SNES AYE]

If there's a specific game you have in mind we might investigate why they did this that way.

Actually, here's a Super Bomberman 2 example, where I'd be curious to hear your opinion on why you think they went with a 2bpp status bar rather than a 4bpp status bar there.

[Bregalad]

Actually, here's a Super Bomberman 2 example, where I'd be curious to hear your opinion on why you think they went with a 2bpp status bar rather than a 4bpp status bar there.

TBH I don't think there's any particular reason. Since this game's graphics are relatively simple for SNES standards, I assume they probably could have afforded the extra space for 4BPP tiles.

[93143]

Not every game was attempting to be a technical showcase. Often, developers would simply do the first thing that came to mind that worked.

Super Bomberman 2 uses BG1 for large bosses, BG2 for the playfield (including bomb effects), and BG3 for the status bar and onscreen text. Sounds reasonable. Why mess around with HDMA and multiple tilemaps when the obvious approach works fine?

Some developers (myself included) do like their games to be technical showcases. It tends to take a lot longer and isn't necessarily the optimal choice in a fast-paced commercial environment. My infamous shmup port has been in development hell for longer than the SNES lasted in the market.

[SNES AYE]

Not every game was attempting to be a technical showcase. Often, developers would simply do the first thing that came to mind that worked.

Super Bomberman 2 uses BG1 for large bosses, BG2 for the playfield (including bomb effects), and BG3 for the status bar and onscreen text. Sounds reasonable. Why mess around with HDMA and multiple tilemaps when the obvious approach works fine?

Some developers (myself included) do like their games to be technical showcases. It tends to take a lot longer and isn't necessarily the optimal choice in a fast-paced commercial environment. My infamous shmup port has been in development hell for longer than the SNES lasted in the market.

Yes, I think you're correct that not every game on the SNES was aiming to be a technical showcase. In fact, I believe most of them weren't particularly focused on that; instead, they took the most straightforward approach with the least friction to get their games made within the short development times they had. And it makes sense in that context.

[psycopathicteen]

I always found it annoying how so many game journalists act like every single game is "limit pushing".