Scrolling in Turrican saga

[jason9]

Can someone please clarify me what kind of scrolling technique is used on the Turrican saga on CPC (1 & 2)? "Hardware" scrolling? And can it be considered the best technique for the CPC in terms of scrolling? Thanks.

[Sykobee (Briggsy)]

Given the small screen size and low frame rate, I suspect it's a double buffered software scrolling, rather than doing anything in hardware.


However it is possible it's using the character-sized hard scroll, I'd have to check it out again.


Regardless, the small screen size makes the game very difficult, especially as the character gets close to the edge as its scrolling.


It's one game I'd love to see a Plus hack, that used the Plus's hardware scrolling and hardware sprites and thus allowed a larger play area (although I guess the entire rendering engine would need rewriting). Also having 512KB of ROM would allow for even more varied graphics.

[arnoldemu]

Turrican 1 is double buffered, hardware scroll, char by char.
The screen uses rupture to split the top and the panel.

Turrican II is double buffered software scroll.

[Carnivius]

It's one game I'd love to see a Plus hack, that used the Plus's hardware scrolling and hardware sprites and thus allowed a larger play area (although I guess the entire rendering engine would need rewriting). Also having 512KB of ROM would allow for even more varied graphics.

If you're gonna do that you may as well just play the Amiga version and that way have the excellent soundtrack too.  Seems like a waste of time and effort. I enjoy the CPC Turrican games as they are.  Not as good as the Amiga versions but very enjoyable in their own unique chunky ways.

[jason9]

Thanks! I would never say they had different scrolling techniques, to me they look quite identical in the scrolling.
Are those two types the best available for the Amstrad CPC capacity? Or eventually can you name me some games particular excellent in the scrolling coding? I would like to make a selection and play them all. For example I know Edge Grinder has a great scrolling technique, but still never played it...

[Nich]

Are those two types the best available for the Amstrad CPC capacity? Or eventually can you name me some games particular excellent in the scrolling coding? I would like to make a selection and play them all.

Titan amazed me back in the day with its fast hardware scrolling.

[reidrac]

There are few new games with scroll ranging from ok to excellent. Edge Grinder or Relentless are good examples of excellent scrolling, both shooters.

Linaje real is another recent game with scroll, and is not a shooter.

On classic games, Deliverance has good scrolling, although is not the usual example.

[ervin]

Titan amazed me back in the day with its fast hardware scrolling.

TLL seems to use a similar technique.
It's ridiculously fast when it hits top speed.

Prohibition also scrolls very well.

[ukmarkh]

There are few new games with scroll ranging from ok to excellent. Edge Grinder or Relentless are good examples of excellent scrolling, both shooters.

Linaje real is another recent game with scroll, and is not a shooter.

On classic games, Deliverance has good scrolling, although is not the usual example.

Try BraveStarr, Boulderdash and Beyond the Ice Palace for smooth scrolling.

[jason9]

Yes I knew Bravestar and played it back in the old days, thanks for the other suggestions...wow Titan it's a surprise, I watched a gameplay in youtube and it's incredibly fast... How did they achieved it?[size=78%] [/size]

[felow]

some of the latest titles commercially released for the CPC has very good scrolling (Prehistorik 2, Jim Power, Super cauldron), IMHO. I've always found  By the way, back to Turrican for a moment: was the disk version identical to the tape one (for both titles)? Someone knows if the levels-stages are identical to the Amiga versions? (I mean as structured...

[Arnaud]

Turrican 1 is double buffered, hardware scroll, char by char.
The screen uses rupture to split the top and the panel.

Turrican II is double buffered software scroll.

Turrican II seems to be faster than Turrican I.
Hardware scroll should not be faster than Software scroll ?

Every year i take a look on the cpcretrodev source code to see if a multidirectionnal scrolling hardware is used in a game, but it seems too difficult to code.

[Axelay]

Turrican II seems to be faster than Turrican I.
Hardware scroll should not be faster than Software scroll ?

I had a feeling the first Turrican didn't hardware scroll so I just checked it, and it doesn't, although it does use a screen split.  But even if Turrican had hardware scrolled, speed isn't guaranteed with that, it depends on other demands on cpu time as well.  You still need to use software sprites and they are typically going to be more time consuming on a hardware scrolled screen than on a software scrolled screen.

[reidrac]

I had a feeling the first Turrican didn't hardware scroll so I just checked it, and it doesn't, although it does use a screen split.  But even if Turrican had hardware scrolled, speed isn't guaranteed with that, it depends on other demands on cpu time as well.  You still need to use software sprites and they are typically going to be more time consuming on a hardware scrolled screen than on a software scrolled screen.

Can you elaborate on that?

People keep raving on the CPC having hardware scroll yet few of my favourite games do software scroll and they move and play just fine.

[Sykobee (Briggsy)]

Hardware scroll is great for fairly static layouts, maybe a player sprite and a few enemies. The pain is with the sprite and bullet movement, explained later. Additionally the hardware scroll is 4 MODE 0 pixels in step, which might not be enough. Sure, there are ways to make it smoother, they take memory, especially when you get to the stage of pre-shifted sprites.


Turrican was rather intense in terms of sprite count, sprite size, and bullets.


Memory use is also an issue. You need to track dirty tiles and re-render them before re-rendering the sprites with hardware scroll anyway. Or you copy the background to a buffer to copy back when the sprite moves. A pain, and I can imagine that free memory for this was in short supply in Turrican.



Note that software scrolling (via re-rendering) enables animated waterfalls - if you're redrawing it, you can animate it. Wizard Willy even added parallax, but the frame rate was abysmal.


The Plus, by giving us hardware sprites as well as hardware scroll, got the balance right. And then games often used the sprites for spot gfx (Switchblade) instead of moving objects which stayed as software sprites! Heh.

[arnoldemu]

I had a feeling the first Turrican didn't hardware scroll so I just checked it, and it doesn't, although it does use a screen split.  But even if Turrican had hardware scrolled, speed isn't guaranteed with that, it depends on other demands on cpu time as well.  You still need to use software sprites and they are typically going to be more time consuming on a hardware scrolled screen than on a software scrolled screen.

Yes I see now it's not hardware scrolling. I'm happy to be corrected.

[Axelay]

Can you elaborate on that?

People keep raving on the CPC having hardware scroll yet few of my favourite games do software scroll and they move and play just fine.

Sykobee has covered some of the issues I had in mind, but I also meant that with commercial era games, there was I guess pressure to fit a lot of graphical content into a game in 64k, so if you are swapping sprite facings, decompressing, recolouring, or pixel shifting sprites on the fly, or if you have a single screen with no buffer and are using certain techniques to avoid flicker, then these are all things that could slow down a game.  Hardware scroll or not.


But I didn't mean my original comment to be negative about hardware scrolling.  I personally don't see that smoother hardware scrolling takes more memory, necessarily.  Certainly not fine vertical scrolling.  Smoother hardware horizontal scrolling can require a double buffer with some approaches, and I've seen people say double buffering is not practical in 64k, but I don't agree with that either.  At least, it's not something I've found insurmountable.


I also wouldn't characterise dealing with restoring the background for sprites on a hardware scrolled screen as a pain.  Sure it's more involved, but like any problem, when you've solved it once, doing it again is straight forward.


But I do have a bias towards trying to use hardware scrolling where possible because I feel it represents an area of unrealised potential on the CPC.  Software scrolling I find less interesting because I think the best commercial era coders have more or less explored the possibilities already.

[felow]

some of the latest titles commercially released for the CPC has very good scrolling (Prehistorik 2, Jim Power, Super cauldron), IMHO. I've always found  By the way, back to Turrican for a moment: was the disk version identical to the tape one (for both titles)? Someone knows if the levels-stages are identical to the Amiga versions? (I mean as structured...

Anyone? 

[Cholo]

Anyone? 

Amstrad disc version definately has the 99,99% same level layout .. even the flying shooter sections .. as the amiga version. There are of cause the "size" differences in blocks and colours so the Amiga version is a lot more "room"-y. Even secret powerup blocks seem to be in the same locations. Also i recognize the same layout "traps" like you can get stuck on the alien level if you are too trigger happy and shoot out the sculls (that you need to jump on to exit the map by jumping up). Amstrad is clearly the hardest one because of the "squeezed" screen & heavy controls alone.


Biggest difference is probably in the enemy/traps & behavior. So its not just that green acid drops is blue on the amstrad, there is some speed differences & even replaced traps like i dont recall seeing the bounching steel ball or falling spike grid on the amstrad (replaced with flying mines & "space invader" lasers). Also if i recall right you cant shoot while in ball form on the amstrad thus some areas on the amiga you can easily navigate thru but on the amstrad you will need to find a "work-around". Enemy Boss sizes also do vary a bit but that is understandable but perhaps not the way you think. Like the final boss on the Amstrad always felt giant in my eyes, but when i saw the amiga final boss my first thought was "what that tiny thing"?. Perhaps the amiga suffers a bit here from being too powerfull .. all the bosses are giant, so perhaps that is why i wasnt impressed.


All in all, incredible similar games. Oh and i havnt tried the amstrad tape version, but im guessing there is no difference (except a lot of waiting time).

[felow]

Thanks very much Cholo! Extremely detailed and useful. Did you ever had a chance also to compare CPC and Amiga versions of Turrican 2?

[Cholo]

Thanks very much Cholo! Extremely detailed and useful. Did you ever had a chance also to compare CPC and Amiga versions of Turrican 2?

Never really gotten around to play Turrican 2 myself, but ive saw Xyphoe's longplay of the amstrad version & has also seen a amiga longplay a while back & that game too seem to have the very same level layout too ascross the two versions.