Dual Playfield - Was it avoided because of speed or colors or something else?

[sokolovic]

Originally Posted by 7-Zark-7

If you look up the earlier game diary entries for Uridium II in The One Amiga, Andrew Braybrook touches on early in it's development working on a dual playfield version, but ended up dropping the idea in favour of the released 32 colour version.

He has mentioned on twitter in the past had the A1200 been more successful (with the focus on OCS/ECS Amigas),it's an idea he'd liked to have tinkered more with some extra colours/CPU power to play with.

Doesn't the AGA version of Fire and Ice use dual playfield ?

[lionagony]

Yup https://x.com/UridiumAuthor/status/1...507309921?s=20

[sokolovic]

Originally Posted by lionagony

Yup https://x.com/UridiumAuthor/status/1...507309921?s=20

Thankfully they made an option to choose chipmusic instead of CD one.

[rothers]

Originally Posted by Jobbo

Arabian Nights was excellent! It's dual-playfield everywhere even without the parallax.

That lets the main sprite sit in-between foreground and background tiles. It also makes it faster to restore the dirty rectangles for blank areas of the foreground. You also don't need to store/handle all the unique combinations of foreground and background tiles when dual-playfield is doing it for you so it saves memory and/or time.

It's a really nice engine and the game is really fun!

Wow I'd never noticed that. OK Arabian Nights is now my favourite use of dual playfield.

[alain.treesong]

And finally, after all these messages, the truth triumphs : many OCS games use the dual playfield mode.
Chuck Rock 1, Shadow of the Beast, Arabian Nights, Shadow Fighter and many others including of course the little masterpiece "Shadow of the Beast 3"...

[lionagony]

Originally Posted by rothers

Wow I'd never noticed that. OK Arabian Nights is now my favourite use of dual playfield.

Not sure if you've seen this post from 2016 but it was one of my favourites so I bookmarked it about Mega Typhoon https://eab.abime.net/showpost.php?p...5&postcount=23 That game also used dual playfield but without parallax. What is so interesting is that @Master484 says this:

"I'm now convinced that the Mega Typhoon engine is a work of a genius, and the fastest shooter engine on Amiga 500. What if the dual playfield, used in the way as it's used here, was always the right technique to use if you wanted to make fast shooters on the Amiga?

And this would sound just natural; because this is how the Blitter was designed. What if the dual playfield feature was meant to be used in fast games that draw a lot of stuff?

So maybe the Commodore engineers thought it like this: let them have a background screen of 8 colors, and they can put more colors to it with the copper, and a front screen of 7 colors and transparency, where all moving object drawing happens quickly with 3 bitplanes, and again more colors will come from the Copper and sprites. And so a 32 color action game runs at 50fps, because all drawing actually happens in 8 color BOBs and sprites.

But for some reason no-one at Commodore told this to us, until at 1996 some developer finally figures it out and makes a game like this.

Most other shooters that I know use either one 16 color playfield, or parallax dual playfields that waste steam for parallax effects, but none have this many moving objects on screen at 50fps."

and in a later post in that thread https://eab.abime.net/showpost.php?p...6&postcount=26

"That's some awesome sprite multiplexing, so many bullets on screen with just 4 sprites...so this is almost like copper sky gradient changes, but done for sprites. It's like a "sprite gradient"; just like color registers can be multiplexed across the screen, so can sprites.

It's quite funny actually, everyone knew that Amiga is capable of multiplexing sprites, but so few games actually used the feature, and none used it to it's full potential, except this one game.

And the game also draws an insane amounts of BOBs too, and still runs at 50 fps, without any slowdown happening, ever.

And if the "Battle Squadron trick" (updating Player and scrolling at 50 fps but enemies at 25 fps) would be added to this game, then it could draw even more BOBS to screen, or even larger bosses.

And indeed on AGA 16 color dual playfields this would look even more awesome; any arcade coin-op shmup is 100% possible on the Amiga. "

The Amiga still has so much untapped potential! Hopefully the Reshoot games are just the beginning of finally tapping into it.

[AestheticDebris]

I'd say it's pretty obvious the design of DP was that there would be a single background and then a foreground area into which Bobs could be drawn without having to spend a lot of effort preserving background. Compared to 8-bit games that would have been fantastic. But by the time it became mainstream, there was an increasing expectation of some degree of parallax and so the focus was on whether you could effectively use the DP to pull off the effect, requiring that both one of the background layers and the bobs shared a playfield.

[Photon]

Originally Posted by 7-Zark-7

He has mentioned on twitter in the past had the A1200 been more successful (with the focus on OCS/ECS Amigas),it's an idea he'd liked to have tinkered more with some extra colours/CPU power to play with.

I'm friends with Andrew on Twitter, and A500 can do Uridium and Uridium II 50Hz any day of the week. Take from that what you want.

Uridium II wasn't the smash hit of Uridium, and the most likely reason for that was the O.O.P.S. and the usual - graphics resources for screenshots in magazines. They did affect game ideas.

My notion is, a straight port with a graphics upgrade would have been played to death. It didn't happen that way. Decisions out of fear are wrong, as always.

@thread also, sometimes a second playfield is a waste of a playfield. Just dead background. Insert many arcade PCB shooters on many platforms here.

[lionagony]

Originally Posted by AestheticDebris

I'd say it's pretty obvious the design of DP was that there would be a single background and then a foreground area into which Bobs could be drawn without having to spend a lot of effort preserving background. Compared to 8-bit games that would have been fantastic. But by the time it became mainstream, there was an increasing expectation of some degree of parallax and so the focus was on whether you could effectively use the DP to pull off the effect, requiring that both one of the background layers and the bobs shared a playfield.

Mega Typhoon is so amazing for what it can put on the screen and the frenetic pace for the A500 though. It makes me think something along the lines of the Treasure games like Gunstar Heroes and Alien Soldier but without the parallax (or using the odd sprite for parallax like the flowers in Apidya) could be done on the A500 with the Mega Typhoon techniques. I saw an article the other day where one of the main guys at Treasure said the Mega Drive was better than the SNES because of the 68000, they loved the 68000 and said it's multiplication power was so important to do things like multi-jointed bosses etc https://www.timeextension.com/featur...tter-than-snes Would be interesting to know what the Treasure guys could have done on the Amiga.

[sokolovic]

At the beginning of Alien Soldier there is even written something like "it's time to unleash the power of the 68000" which was very uncommon for a console game.

[rothers]

Yes I think that's how it was meant to be used too. It's such a shame Commodore didn't really push any of these ideas at the time.

Leaving it for coders to figure out was a shame.

We could have had a lot of console style games at 50fps if this route had been used more.

[DanScott]

Mega typhoon is an amazing use of DPF and sprites. Vertical shooters are great for using the amiga hardware to the max. Anything horizontal or 8 way scrolling has a lot more restrictions

[DanScott]

For example, with an any direction scroll, you'll be using the copper to write the bitplane pointers at some arbitrary position down the screen. Mixing this with heavy copper sprite reusing and colour changes can be a headstress ??

[7-Zark-7]

Originally Posted by Photon

I'm friends with Andrew on Twitter, and A500 can do Uridium and Uridium II 50Hz any day of the week. Take from that what you want.

Uridium II wasn't the smash hit of Uridium, and the most likely reason for that was the O.O.P.S. and the usual - graphics resources for screenshots in magazines. They did affect game ideas.

My notion is, a straight port with a graphics upgrade would have been played to death. It didn't happen that way. Decisions out of fear are wrong, as always.

@thread also, sometimes a second playfield is a waste of a playfield. Just dead background. Insert many arcade PCB shooters on many platforms here.

I seem to recall a comment he made in the diary entry of the time how the dual playfield idea looked effective seeing it in action,but as you say,back then when we'd be judging static shots in magazines etc.

Heck,even the bonus game with blasting the reactor core between levels was quite different to an overhead view idea featured in the first diary entry or so!

Reminds me one time when he was talking about their Rainbow Islands PS1 port having cloud transparencies in its background in the first island & speculating if he could've managed it on an A1200 too.

[7-Zark-7]

Originally Posted by DanScott

Looking at the long play, Arabian nights seems to use dual playfield (certainly on the levels with parallax... Not enough sprites for it to be done with those)

Again, stretching the old brainbox from my youth, but seem to recall a preview of Soccer Kid mentioning both they & the Arabian Nights devs using the same base engine & touching on a bit of competitive rivalry in the offices.

But I'm guessing a lot of the "bigger" teams of the era,whether Core, Ocean etc., all probably had their roller coaster rides of occasional personality clashes,& moreso deadlines etc., all affecting people's moods or how protective they might've been of a new programming trick back in the day!

[aros-sg]

Originally Posted by DanScott

For example, with an any direction scroll, you'll be using the copper to write the bitplane pointers at some arbitrary position down the screen.

It's possible to do 8 way scroller without vertical copper split. 3 normal sized "virtual" buffers vertically stacked inside a single 3x(height+saftey_gap) masterbuffer where the wrap around happens at the bottom of the masterbuffer (y coord = 3 x height). With some precautions you should then always have 2 of the 3 buffers not-wrapping at all = no copper split necessary. During vertical scrollilng the buffers basiocally move around vertically in the master buffer, and wrap back to the top if they cross the bottom of the masterbuffer.

[sokolovic]

That makes me thinks... Is it possible that Legends on the A1200 use an AGA dual playfield mode ?

[lionagony]

Originally Posted by sokolovic

At the beginning of Alien Soldier there is even written something like "it's time to unleash the power of the 68000" which was very uncommon for a console game.

Yeah, and Mega Typhoon boasts more than 100 moving objects on the screen at one time with up to 64 bobs and 48 sprites. I don't think Alien Soldier or Gunstar Heroes or Dynamite Headdy have that number many if any times. The Mega Typhoon readme file has some technical info in German only. I Google translated it but would be nice if any German speaker on here could verify if the translation is correct and if they would add any nuance. Here's the original German:

Vitual Playfield Scrolling: ( IFF ) - Graphic-Brushes beliebiger Größe,
können an jeder beliebigen Pixel - Position auf dem virtuellen Hinter-
grund plaziert werden, welcher mit beliebiger Geschwindigkeit gescrollt
werden kann. ( Größe des Virtual Playfields: bis zu 448 x 1684 Pixel )

Copper Controled Blitter: Alle Blitter-Operationen verlaufen Copper-
gesteuert, unabhängig von der CPU im Hintergrund ( Mit zunehmender An-
Zahl der BOBs erreicht dieses Verfahren gegenüber dem herkömmlichen
" Blitter-finished-Interrupt-Chaining ", wegen der relativ langsamen
Interrupt-Verarbeitung, eine Performance-Steigerung um bis zu 30%.

Interleaved Bitplane Format und Blitter Optimized Coodinate Fomat (BOC)
zur weiteren Reduzierund des " Blitter-Overheads ".

Animation/Control Process Separation: Dank dieser völlig neuartigen
Technik, bei der der gesamte Programmablauf in 3 unabhängige, asynchron
kommunizierende Prozesse aufgeteilt wird, ist die sichtbare Frame-Rate
( 50 Hz ) in keinster Weise durch die CPU-Berechnungen beschränkt, son-
dern ausschließlich durch den Blitter. Das heißt: selbst aufwendige
Berechnungen, wie z.B. 50 gleichzeitig laufende Zielsuch-Algorithmen
verlangsamen die Bildwiederholrate nicht!

Systemkonforme Programmierung, Kompatibilität: Trotz der auf die Spitze
getriebenen Ausreizung der Hardware, wurde das Programm so systemkon-
form wie möglich konzipiert. Der hardwarespezifische Teil des Programm-
codes ist über wohldefinierte Schnittstellen vom übrigen Programm abge-
kapselt, welches ausschließlich Standard-Systemfuntionen verwendet. So
läßt sich " Mega-Typhoon " z.B. problemlos auf Festplatte installieren
und wurde auf allen AMIGA-Modellen (A1000, A500, A2000, A12000, A4000)
erfolgreich getestet.

and here's the Google translation:

Virtual Playfield Scrolling: (IFF) - Graphic brushes of any size,
can be placed at any pixel position on the virtual background
reason can be placed, which scrolls at any speed
can be. (Size of the Virtual Playfield: up to 448 x 1684 pixels)

Copper Controlled Blitter: All blitter operations are copper-controlled.
controlled, independent of the CPU in the background (with increasing
This method achieves the number of BOBs compared to the conventional one
"Blitter-finished interrupt chaining", because of the relatively slow
Interrupt processing, a performance increase of up to 30%.

Interleaved Bitplane Format and Blitter Optimized Coodinate Format (BOC)
to further reduce the “blitter overhead”.

Animation/Control Process Separation: Thanks to this completely new
Technology in which the entire program flow is divided into 3 independent, asynchronous
The visible frame rate is divided into communicating processes
(50 Hz) is in no way limited by the CPU calculations, but
but only through the Blitter. That means: even complex ones
Calculations, such as 50 target search algorithms running simultaneously
does not slow down the refresh rate!

System-compliant programming, compatibility: Despite the extremes
driven to the fullest extent of the hardware, the program was designed to be system-compatible
designed as possible. The hardware-specific part of the program
codes is separated from the rest of the program via well-defined interfaces.
encapsulates, which only uses standard system functions. So
For example, “Mega Typhoon” can be easily installed on the hard drive
and was installed on all AMIGA models (A1000, A500, A2000, A12000, A4000)
successfully tested.

[sokolovic]

Lionagony, surely Treasure could have made tremendous games on the Amiga. But they didn't.

[ross]

Originally Posted by aros-sg

It's possible to do 8 way scroller without vertical copper split. 3 normal sized "virtual" buffers vertically stacked inside a single 3x(height+saftey_gap) masterbuffer where the wrap around happens at the bottom of the masterbuffer (y coord = 3 x height). With some precautions you should then always have 2 of the 3 buffers not-wrapping at all = no copper split necessary. During vertical scrollilng the buffers basiocally move around vertically in the master buffer, and wrap back to the top if they cross the bottom of the masterbuffer.

Yep, this works

But at the 'wrap' you need an already fully built backbuffer (basically you must have a double image in memory).
In any case, having it could be useful if you use it to reconstruct the 'active' background.