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Dark Fusion by Gremlin Graphics - Scrolling Routine

Started by Axel, 14:40, 16 June 22

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Hello Guys,

I am sure, you know this really pretty looking game. Can somebody explain the scrolling technique behind it? It looks really smooth, and there are a lot of colors on the screen. 

Greets  :)


Do you mean this one?

It may be that it uses a technique similar to the original R-Type. The area that scrolls up and down is not very large, it is possible that it is doing bit rotation there.


Yes, this is the game. Later on in the game there is also an horizontal shooter part, also very smooth.

But I don't think that it scrolls similar to the original R-Type, because the scrolling of R-Type looks a bit "wobbly" and flickery. And why are you talking about "scrolls up and down"?

In this video you can see more gameplay, but not the horizontal part, because the player is not good enough to reach this part.  :laugh:


It uses software scrolling, CRTC register 12 stays at &30 (and 13 at 0). --> Get the revolutionary FutureOS (Update: 2022.03.09) --> Get the RSX-ROM for LambdaSpeak :-) (Updated: 2021.12.26)


Okay, wow, software scrolling. It looks good, doesn't it? Like the graphics too, and the music. 


Software Scrolling can be cool, this is a nice public domain game, but look at the scrolling ;-) --> Get the revolutionary FutureOS (Update: 2022.03.09) --> Get the RSX-ROM for LambdaSpeak :-) (Updated: 2021.12.26)


Looks like a zoomed in view of The Last V8.
- Barry Rodewald


That scrolling reminds me of the stunning Rotovision-Scrolling from "Mission Genocide", maybe not quite as smooth, but maybe the poor quality of the YT-Video is the reason for that.


Yes, videos are always jerky, reality on CTM644 / CM14 is way more smooth.  :) --> Get the revolutionary FutureOS (Update: 2022.03.09) --> Get the RSX-ROM for LambdaSpeak :-) (Updated: 2021.12.26)


Hey, this was a listing! But not Basic I guess, a pack of DATA-Lines. Do you know more? And would this scrolling also be that smooth if the playing area would be larger? "Mission Genocide" was able to, but that was a hardware-scroll, as fas as I know.

And, dear Gunhead, please allow me another question:
Are you really the reincarnation of TFM? Are you the boss of Future Os?


Yes, decent and humble TFM who got kicked out here before for an own opinion... Whatever.  :)
You can extend software scrolling to a part of the screen. If you combine it with hardware scrolling then you can work wonders even. To program hardware scrolling is simple (see unofficial cpc ressource or similar). But - I guess - people like static screens more, because it need less variables to manages sprites and all other stuff.

Using hardware scroll you can even use 32 KB V-RAM and be smooth. Examples for smoot hardware scrolls are Relentless, Alcon, Mission Genocide, our GianaSisters Clone and others.

BTW: Burnin Wheels DSK: --> Get the revolutionary FutureOS (Update: 2022.03.09) --> Get the RSX-ROM for LambdaSpeak :-) (Updated: 2021.12.26)


You are the brilliant creator of Cyber Chicken!  :-*  :-*

Also a great example of good scrolling is "Super Edge Grinder". The scrolling looks superb, and it seems to be full colour. Such a pity it is only a one level thing.

"Alcon" is absolutely stunning too, "full graphics" (not like Mission Genocide in a reduced way) and smooth to the same time.

Your fantastic Giana Sisters Clone will be forever a demo...or can you complete it one day?

(Ich weiß, dass du Deutsch kannst: Mein Englisch ist etwas eingerostet, aber ich bemühe mich, wieder reinzurutschen.)


Glad you like Cyber Chicken, actually I wanted to do a 2nd part with Kangaroos in a desert, but for reasons nobody did the GFX for me. But it would have been a great game.

Giana doesn't need much to be finished. Just need to do couple things before.

(Mein Englisch wird auch immer mieser, bin seit gut 5 Jahren aus New Orleans wieder in München zurück). --> Get the revolutionary FutureOS (Update: 2022.03.09) --> Get the RSX-ROM for LambdaSpeak :-) (Updated: 2021.12.26)


Sad to hear that statement about the undeveloped Desert Chicken.  Seems that some people are not enough on the bright side of life to generate some cool GFX for a game that could be great new stuff for our sweet Amstrad Schneider CPC.  :'(

I know your demo of "Giana Sisters" since approximately 2010. It would be a highlight to see the full game one day.

Can you tell me something about how the scrolling of "Zynaps" was made? I remember back in the days it was an achievement to run a horizontal shooter game on the CPC that fast without slowdowns etc. Okay, it is not really smooth, but it is fast and stable.

This one scrolls also fine vertical. It is from 1990 and a Ikari-Warriors-Style shooter game:


You can use a CPC emulator (like WinCPC or JavaCPC) and stop a game in debugging mode. Then look at CRTC registers &0C and &0D a couple of times, means while the screen scrolls.
If the content of CRTC registers 12 and 13 does change, then you can assume that hardware scrolling is used.  :) --> Get the revolutionary FutureOS (Update: 2022.03.09) --> Get the RSX-ROM for LambdaSpeak :-) (Updated: 2021.12.26)



I am still wondering about the scrolling of "Zynaps". It seems to scroll soft in small pixel sizes but is a bit "shaky" to the same time. What is the reason? Between every "shake" it scrolls good. 


My two cents here.

Zynaps is software scrolled, with double buffer.
Tilemap is scrolled 2 byte units (4 pixels mode 0), at every update cycle (3 frames per cycle, so 16.66 fps).
It runs smooth at this cadence with minor lags on concrete situations with too much sprites or bigger sprites on screen.

Did you run it on real hardware, emulator, or just seen the video above?
In the later cases, you must take into account emulators and video capturing software are playing it's rol, hence the shaky part.

"Relentless" is also a good example of smooth horizontal scrolling making use of R3 register, like "Giana Sisters"


I played it on real hardware back then. I can't really remember if the scrolling was shaky all the time or in dependent on the amount of action on the screen. What I remember is, that Zynaps was technically striking good for the Amstrad back then, the scrolling and speed very well made. Compare it with "Sidearms" for example and you know what I mean.

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