Author Topic: Hypothetical PCE port :: Flame Zapper Kotsujin  (Read 2969 times)

Michirin9801

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Hypothetical PCE port :: Flame Zapper Kotsujin
« on: April 05, 2017, 05:45:16 PM »
Some of you may already be familiar with this phenomenal PC-98 Doujin Shmup, personally it's one of my favourites in the genre, easily my No. 1 on the system (not like there's much competition)
For those who aren't, here's a little video of it:


So, since the PCE is the king of shmups, it would only make sense for me to imagine what would this game look, sound and play like on the system right?
Well, anybody who's listened to my album (Which btw can be found here: https://michirin9801.bandcamp.com/releases) already has kind of an idea what this game could sound like on the PCE, but then there's the whole rest...

As far as I'm aware, the PC-98 is even more limited than the PCE in terms of parallax scrolling, the thing can't even smoothly scroll a background horizontally, it has to do that tile by tile, or do some witchcraft like C-Lab and Melody did when they were making Rusty, Totsugeki Mix and Night Slave, that said though, the system has no issues with vertical scrolling, most likely because it was meant to scroll text... It also only has 1 BG layer btw, and its "sprite layer" isn't technically a "sprite layer" per-se, it's complicated and I don't know the specifics...

Anyway, with that in mind, this game pulls off loads of parallax scrolling on the system, which is a bit of a rarity in case you couldn't tell by the aforementioned limitations! Well, being able to show a whole load of sprites on-screen without flickering does help it pull that off, but you know, I was wondering how that could be done on the PCE, because well, the limited amount of sprites on-screen and per-scanline would certainly bottleneck what you could do without flickering... As you can see in the video, this game throws bullets and enemies at you like there's no tomorrow, add the BG sprites on top of that and it will certainly flicker, but still, I'd really like to see the PC engine doing something like that...

The parallax isn't the only thing I've been thinking of though, but also about the resolution, you see, this game runs on a mode on the PC-98 that cuts the horizontal resolution to 448 pixels as opposed to the usual 640, and that allows this game to run at 60fps, or at least I'm assuming it does, because every PC-98 game I've ever seen running at 60fps uses this mode (Rude Breaker and Touhou come to mind) but you can still display still graphics and text on the unused horizontal resolution which is nice and is how they did the HUD for this game (and for Touhou too), so I was thinking of different ways we could port the graphics, parallax aside, to the PC engine, and I have 2 ideas:

1 - We could use the 512 pixel mode to do a near-perfect port of the game's graphics (side-bar HUD aside, unless you'd be okay with making it only 64 pixels wide, which honestly, isn't enough), but well, I don't think that would be the best idea, because that would mean more flickering and we'd only be using 16 colours for the graphics, which honestly, sounds like a complete waste of the system's colour potential, not like we need to make it hyper colourful or anything, but with just a few extra colours we could make the PCE version look even better than the PC-98 one at half the resolution, which leads me to:

2 - Use the 320 pixel mode, remake the graphics to better suit the PCE (but still keep them somewhat close to the original) why the 320 pixel mode and not the 256 one you ask? Because that way we'd be working with exactly half the PC-98's horizontal resolution, so we could make the gameplay take place on a 224 pixel play field on the left and have a 96 pixel side-bar with the HUD on it on the right, so it would look just like the original! That bar would of course be rendered as a vertical stripe of the BG and no sprite would ever be on top of it, that way we'd be able to cover the entire horizontal length of the 'background' with only 7 sprites, not that it would be needed very often, but still...

I imagine you could also flicker some sprites by priority, like for example stars behind the BG, they wouldn't be missed too much in case of there being too many sprites on the same scanline, and of course, we'd have to tone down the amount of bullets some enemies throw at you, and the number of 'floors' the buildings in stage 2 have, (the ones in stage 4 and the end of stage 3 could be done with vertical BG stripes) there are also some clever zooming and rotation effects that could be done by moving different vertical stripes of the BG apart from one another and moving sprites around respectively...

Back on the topic of sound, this game has 2 versions of the soundtrack, there's the MONO version for the YM2203 (OPN) soundchip, and the Stereo version for the YM2608 (OPNA), and some of the compositions are actually different depending on which version you pick, and even the ones that aren't sound pretty different depending on the soundchip, so I was thinking, wouldn't it be awesome if this theoretical PCE port also had 2 versions of the soundtrack?
Like, we could do PSG covers of the MONO version for the regular old PCE, and covers of the Stereo version for systems with CD attachments and the DUOs, those would take advantage of the ADPCM channel to play percussion and free up a channel to do some phasing, reverb or play a triad instead of a power chord! But of course, both versions of the soundtrack would be in Stereo, so the versions would need to be renamed "PSG" and "CD" as opposed to "MONO" and "Stereo", also yes, we'd do this on a Hu-Card... (There goes my dream of making a Hu-Card game with support for sampled percussion on the CD ADPCM again)

I think I've already rambled for long enough, keep in mind this is all hypothetical, it's probably never gonna happen, and even if it did happen it would most likely be just a 1 stage demo, this is all just some food for thought, but yeah, I like to imagine what this game would be like on the PCE...

elmer

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Re: Hypothetical PCE port :: Flame Zapper Kotsujin
« Reply #1 on: April 06, 2017, 10:57:37 AM »
As far as I'm aware, the PC-98 is even more limited than the PCE in terms of parallax scrolling, the thing can't even smoothly scroll a background horizontally, it has to do that tile by tile, or do some witchcraft like C-Lab and Melody did when they were making Rusty, Totsugeki Mix and Night Slave, that said though, the system has no issues with vertical scrolling, most likely because it was meant to scroll text... It also only has 1 BG layer btw, and its "sprite layer" isn't technically a "sprite layer" per-se, it's complicated and I don't know the specifics...

A quick look around shows ...

http://island.geocities.jp/cklouch/column/pc98bas/pc98disphw_en.htm

The PC98 display is just a 16-color planer (4-plane) 640x400 bitmap, with 2 pages (i.e. a back-buffer) if you're targeting the 1986+ EGC models (which I presume that Kotsujin is).

There's no hardware scroll, so you're pretty screwed when it comes to horizontal scrolling, but you can change the start-address on a 16-pixel-word boundary, and vertical scrolling is possible.

BUT ... when you're displaying that much data on-screen, the vertical scroll is pretty-much pointless for games, because you've got to rewrite the whole display area anyway in order to draw over the last frame's "sprites".

The huge sidebar is there to cut down the amount of data that you have to write each frame so that they can keep that 60fps.

It was a common trick on computers to help mask the fact that your machine isn't powerful-enough to do full-screen scrolling.


Quote
Anyway, with that in mind, this game pulls off loads of parallax scrolling on the system, which is a bit of a rarity in case you couldn't tell by the aforementioned limitations! Well, being able to show a whole load of sprites on-screen without flickering does help it pull that off, but you know, I was wondering how that could be done on the PCE, because well, the limited amount of sprites on-screen and per-scanline would certainly bottleneck what you could do without flickering.

It's got no sprites, so there's no sprite-flicker.

It's just like an Atari ST, but running at a higher resolution, and with a faster processor.

So I imagine that they're drawing the entire game-area of the screen in software, in RAM, and then copying the completed image into VRAM.

What model/specs of PC98 was needed to run the game? 80386 @ 16MHz?


Quote
.. As you can see in the video, this game throws bullets and enemies at you like there's no tomorrow, add the BG sprites on top of that and it will certainly flicker, but still, I'd really like to see the PC engine doing something like that...

I suspect that you'll have a hard time persuading any programmer to work on something that's going to look flickery and compromised "by-design".  :wink:

Poor old fragmare still hasn't got anyone to work on Xymati, and AFAIK that's actually been designed to match up to the strengths of the PCE.

P.S. I don't really understand why you want to keep the sidebar instead of putting the info at the top or bottom of the screen (since the PC98 is only 400-high anyway, which would drop to 200-high on the PCE).  :-k

fragmare

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Re: Hypothetical PCE port :: Flame Zapper Kotsujin
« Reply #2 on: April 06, 2017, 11:28:33 AM »
Lol, yea, I was going to say... I'm sure the PCE could give you a near 1:1 port (or maybe even enhanced) of FZK.  The problem is finding somebody to code it.

Michirin9801

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Re: Hypothetical PCE port :: Flame Zapper Kotsujin
« Reply #3 on: April 06, 2017, 01:17:33 PM »
As far as I'm aware, the PC-98 is even more limited than the PCE in terms of parallax scrolling, the thing can't even smoothly scroll a background horizontally, it has to do that tile by tile, or do some witchcraft like C-Lab and Melody did when they were making Rusty, Totsugeki Mix and Night Slave, that said though, the system has no issues with vertical scrolling, most likely because it was meant to scroll text... It also only has 1 BG layer btw, and its "sprite layer" isn't technically a "sprite layer" per-se, it's complicated and I don't know the specifics...

A quick look around shows ...

http://island.geocities.jp/cklouch/column/pc98bas/pc98disphw_en.htm

The PC98 display is just a 16-color planer (4-plane) 640x400 bitmap, with 2 pages (i.e. a back-buffer) if you're targeting the 1986+ EGC models (which I presume that Kotsujin is).

There's no hardware scroll, so you're pretty screwed when it comes to horizontal scrolling, but you can change the start-address on a 16-pixel-word boundary, and vertical scrolling is possible.

BUT ... when you're displaying that much data on-screen, the vertical scroll is pretty-much pointless for games, because you've got to rewrite the whole display area anyway in order to draw over the last frame's "sprites".

The huge sidebar is there to cut down the amount of data that you have to write each frame so that they can keep that 60fps.

It was a common trick on computers to help mask the fact that your machine isn't powerful-enough to do full-screen scrolling.


Quote
Anyway, with that in mind, this game pulls off loads of parallax scrolling on the system, which is a bit of a rarity in case you couldn't tell by the aforementioned limitations! Well, being able to show a whole load of sprites on-screen without flickering does help it pull that off, but you know, I was wondering how that could be done on the PCE, because well, the limited amount of sprites on-screen and per-scanline would certainly bottleneck what you could do without flickering.

It's got no sprites, so there's no sprite-flicker.

It's just like an Atari ST, but running at a higher resolution, and with a faster processor.

So I imagine that they're drawing the entire game-area of the screen in software, in RAM, and then copying the completed image into VRAM.

What model/specs of PC98 was needed to run the game? 80386 @ 16MHz?


Quote
.. As you can see in the video, this game throws bullets and enemies at you like there's no tomorrow, add the BG sprites on top of that and it will certainly flicker, but still, I'd really like to see the PC engine doing something like that...

I suspect that you'll have a hard time persuading any programmer to work on something that's going to look flickery and compromised "by-design".  :wink:

Poor old fragmare still hasn't got anyone to work on Xymati, and AFAIK that's actually been designed to match up to the strengths of the PCE.

P.S. I don't really understand why you want to keep the sidebar instead of putting the info at the top or bottom of the screen (since the PC98 is only 400-high anyway, which would drop to 200-high on the PCE).  :-k

That sure was a load of interesting info!

You know, I'd prefer to keep the side bar not only for the sake of being close to the original, but also because of having to render less sprites as parts of the BG horizontally than the game would otherwise need, and also, correct me if I'm wrong, but as far as I'm aware, you can only divide the BG layer in stripes in one orientation, either vertical or horizontal, and it would be better for a vertical scrolling shmup to have vertical BG stripes (would be pretty useful in the 2nd half of stage 4) so if you'd render the HUD as part of the BG layer you'd only be able to do it in a vertical stripe, hence why a side-bar would be a better idea...

Lol, yea, I was going to say... I'm sure the PCE could give you a near 1:1 port (or maybe even enhanced) of FZK.  The problem is finding somebody to code it.

The PCE already has a shmup that's even better and more impressive than Kotsujin, it's Soldier Blade, but Kotsujin sure would be a worthy addition to the system's library wouldn't it? ;3
It would feel right at home~

Honestly though, this is all just food for thought and imagination, if I were to actually go and make a shooter for the PCE I'd want to make an original one...

elmer

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Re: Hypothetical PCE port :: Flame Zapper Kotsujin
« Reply #4 on: April 06, 2017, 01:33:48 PM »
1 - We could use the 512 pixel mode to do a near-perfect port of the game's graphics (side-bar HUD aside, unless you'd be okay with making it only 64 pixels wide, which honestly, isn't enough), but well, I don't think that would be the best idea, because that would mean more flickering and we'd only be using 16 colours for the graphics, which honestly, sounds like a complete waste of the system's colour potential, not like we need to make it hyper colourful or anything, but with just a few extra colours we could make the PCE version look even better than the PC-98 one at half the resolution, which leads me to:

Why does the 512-pixel mode limit you to 16 colors?  :shock:

Have I missed something ... I thought that we still had all of our palettes in that mode.  8-[

But what I'm definitely not sure about, is whether running in 10MHz pixel mode actually affects our ability to write to VRAM during the frame.


P.S. I don't really understand why you want to keep the sidebar instead of putting the info at the top or bottom of the screen (since the PC98 is only 400-high anyway, which would drop to 200-high on the PCE).  :-k

Another look at some of the Kotsujin screenshots shows that the game is only running at half-height, i.e. 200 pixels.

So we could run the game at 448x200, and still have space underneath for the status panel.

Perhaps something like this ...




Now ... running in 512-pixel mode would gut the PCE's capability to draw enough sprites to fill the screen ... but ... we do have a solution ... the SuperGrafx!  :wink:

The SuperGrafx should be able to do a pretty-much pixel-perfect, and color-enhanced version of Kotsujin.

Getting a 1996 game running in hi-res on a 1989 console, and potentially showing the SuperGrafx's superiority over the SNES and the Megadrive, that could be ... interesting.  :-k

elmer

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Re: Hypothetical PCE port :: Flame Zapper Kotsujin
« Reply #5 on: April 06, 2017, 01:45:56 PM »
You know, I'd prefer to keep the side bar not only for the sake of being close to the original, but also because of having to render less sprites as parts of the BG horizontally than the game would otherwise need, and also, correct me if I'm wrong, but as far as I'm aware, you can only divide the BG layer in stripes in one orientation, either vertical or horizontal ...

I think that you're confusing us with the Megadrive.

The vertical-scroll registers are one of the few nice things about the Megadrive, and allow it to do that side-by-side split-screen thing.

We don't have that hardware capability on the PCE (IIRC the SNES doesn't have it, either).

For us ... you'd want the status bar on the top or bottom.

Displaying a 448-wide playfield on a 512-wide graphics mode would give a nice vertical shmup feel to the game.

elmer

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Re: Hypothetical PCE port :: Flame Zapper Kotsujin
« Reply #6 on: April 06, 2017, 02:29:15 PM »
The PCE already has a shmup that's even better and more impressive than Kotsujin, it's Soldier Blade, but Kotsujin sure would be a worthy addition to the system's library wouldn't it? ;3
It would feel right at home~

Honestly though, this is all just food for thought and imagination, if I were to actually go and make a shooter for the PCE I'd want to make an original one...

One big problem with making your own is to generate enough assets for it to look really good.

I'm a little surprised that nobody has suggested converting Tyrian over to the PCE, especially since the code is open-source, and the graphics are all available, and lo-res ... and pretty.

http://www.lostgarden.com/2007/04/free-game-graphics-tyrian-ships-and.html





<edit>

Although, personally, I'm more fond of a shmup that makes you think-and-panic rather than just a bullet-hell (timecode 5:10 if the link doesn't work properly).


« Last Edit: April 06, 2017, 02:55:12 PM by elmer »

Michirin9801

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Re: Hypothetical PCE port :: Flame Zapper Kotsujin
« Reply #7 on: April 06, 2017, 03:02:24 PM »
1 - We could use the 512 pixel mode to do a near-perfect port of the game's graphics (side-bar HUD aside, unless you'd be okay with making it only 64 pixels wide, which honestly, isn't enough), but well, I don't think that would be the best idea, because that would mean more flickering and we'd only be using 16 colours for the graphics, which honestly, sounds like a complete waste of the system's colour potential, not like we need to make it hyper colourful or anything, but with just a few extra colours we could make the PCE version look even better than the PC-98 one at half the resolution, which leads me to:

Why does the 512-pixel mode limit you to 16 colors?  :shock:

Have I missed something ... I thought that we still had all of our palettes in that mode.  8-[
It doesn't, I've only suggested the 512 pixel mode so that we could use the same assets as the original game, and said assets only use 16 colours so... Yeah...

You know, I'd prefer to keep the side bar not only for the sake of being close to the original, but also because of having to render less sprites as parts of the BG horizontally than the game would otherwise need, and also, correct me if I'm wrong, but as far as I'm aware, you can only divide the BG layer in stripes in one orientation, either vertical or horizontal ...

I think that you're confusing us with the Megadrive.

The vertical-scroll registers are one of the few nice things about the Megadrive, and allow it to do that side-by-side split-screen thing.

We don't have that hardware capability on the PCE (IIRC the SNES doesn't have it, either).

For us ... you'd want the status bar on the top or bottom.

Displaying a 448-wide playfield on a 512-wide graphics mode would give a nice vertical shmup feel to the game.

So you're telling me that you can't divide a BG vertically on the PCE? Only horizontally?
If that's the case then...

So we could run the game at 448x200, and still have space underneath for the status panel.

Perhaps something like this ...




Now ... running in 512-pixel mode would gut the PCE's capability to draw enough sprites to fill the screen ... but ... we do have a solution ... the SuperGrafx!  :wink:

The SuperGrafx should be able to do a pretty-much pixel-perfect, and color-enhanced version of Kotsujin.

Getting a 1996 game running in hi-res on a 1989 console, and potentially showing the SuperGrafx's superiority over the SNES and the Megadrive, that could be ... interesting.  :-k

I suppose that works too, but you know, the fun part would be seeing how we could potentially do this on the less powerful system if you get what I mean >w>

Here's an idea, what if there was a colour-enhanced 256 (or 320) pixel version on the PCE running on a 224 pixel playfield, and a pixel-perfect SuperGrafx version running on a 448 pixel playfield?

touko

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Re: Hypothetical PCE port :: Flame Zapper Kotsujin
« Reply #8 on: April 06, 2017, 08:42:53 PM »
Quote
We don't have that hardware capability on the PCE (IIRC the SNES doesn't have it, either).
The snes has it, but it's by tile(you can see it for exemple in the aladdin's snake level) , not an entire (16 pixels wide,aka 2 tiles) column like MD .

Even on SGX,a pixel perfect conversion of FZ is not feasible,there is too many things on screen IMO .
But you can do a very close one .
« Last Edit: April 06, 2017, 08:52:28 PM by touko »

Michirin9801

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Re: Hypothetical PCE port :: Flame Zapper Kotsujin
« Reply #9 on: April 07, 2017, 05:25:57 AM »
Quote
We don't have that hardware capability on the PCE (IIRC the SNES doesn't have it, either).
The snes has it, but it's by tile(you can see it for exemple in the aladdin's snake level) , not an entire (16 pixels wide,aka 2 tiles) column like MD .
So I take it that the SNES can do it even better than the MD? ;3

touko

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Re: Hypothetical PCE port :: Flame Zapper Kotsujin
« Reply #10 on: April 07, 2017, 07:08:42 AM »
Quote
We don't have that hardware capability on the PCE (IIRC the SNES doesn't have it, either).
The snes has it, but it's by tile(you can see it for exemple in the aladdin's snake level) , not an entire (16 pixels wide,aka 2 tiles) column like MD .
So I take it that the SNES can do it even better than the MD? ;3
Yes but it takes more cpu to do, you needs to set each tile, and it has a better granularity (8 pixels columns) .

It's more flexible, but also more complicated .
https://youtu.be/_inY8qT5UT4?t=38m55s
« Last Edit: April 07, 2017, 07:12:07 AM by touko »

Michirin9801

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Re: Hypothetical PCE port :: Flame Zapper Kotsujin
« Reply #11 on: April 07, 2017, 08:06:34 AM »
Quote
We don't have that hardware capability on the PCE (IIRC the SNES doesn't have it, either).
The snes has it, but it's by tile(you can see it for exemple in the aladdin's snake level) , not an entire (16 pixels wide,aka 2 tiles) column like MD .
So I take it that the SNES can do it even better than the MD? ;3
Yes but it takes more cpu to do, you needs to set each tile, and it has a better granularity (8 pixels columns) .

It's more flexible, but also more complicated .
https://youtu.be/_inY8qT5UT4?t=38m55s
I see... Well that makes sense!

elmer

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Re: Hypothetical PCE port :: Flame Zapper Kotsujin
« Reply #12 on: April 07, 2017, 08:35:32 AM »
It's more flexible, but also more complicated .
https://youtu.be/_inY8qT5UT4?t=38m55s

Hmmm ... I can't be bothered to check the SNES documentation, but ...

That whole effect on that Aladdin background isn't exactly complex. We could do exactly the same on the PCE with a few animated tiles.

Perhaps there are better examples out there.


Even on SGX,a pixel perfect conversion of FZ is not feasible,there is too many things on screen IMO .
But you can do a very close one.

IMHO, the big thing that you'd really need the SGX for are those full-screen "bomb" effects.

They're such an important part of the overall look of Flame Zapper Kotsujin, that butchering them with massive sprite-flicker or background drop-out, would leave you with a poor-quality conversion.

Yes ... there are PCE games that do full-screen weapon effects by writing into the background (GunHed's lightning) ... but those effects are specifically-designed to work that way. The ones in Flame Zapper Kotsujin aren't.


I'd be worried about dropping the resolution down to 224-horizontal, even though that would definitely make things easier.

You could possible get away with it, because a lot of the practical-use of the higher resolution in the PC98 game is as stippling to provide some extra shades on the sprites.

On the PCE we could just use real colors at a lower resolution to achieve the same effect (and probably look nicer).

But there are definitely some cases where details in the sprites would be lost.

The obvious sprite(s) to do as a test case would be the Red Bomb skull animations.

If those can be made to look really good at the 224-horizontal resolution, in PCE colors, then the whole conversion might look decent, even at lo-res.

touko

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Re: Hypothetical PCE port :: Flame Zapper Kotsujin
« Reply #13 on: April 07, 2017, 09:19:31 AM »
Super turrican do it too (on big worms)
https://youtu.be/5EvIIdLWLYY?t=12m30s

Quote
IMHO, the big thing that you'd really need the SGX for are those full-screen "bomb" effects.
Yes if you can accept some flickering .
I thing you are over the 64 pce's sprites on screen and most sprites are 32x32 pixels .

Quote
That whole effect on that Aladdin background isn't exactly complex
You're right, it was only to show that snes can do it, it's more complicated on snes because you must set each tiles individualy, and not a Vscroll entry in a table like on MD .

esteban

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Re: Hypothetical PCE port :: Flame Zapper Kotsujin
« Reply #14 on: April 07, 2017, 03:32:29 PM »
This damn thread raised my hopes.

Then dashed them.

Suddenly, a flicker of hope appeared....

Smothered.

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