Xevious

[Leonie]

Shut your hoar mouth 

Why?
Oh Lord it´s cocaine... 

[ukmarkh]

R-Type may as well be Cocaine. It's a helluva drug... and a helluva game.

Why?
Oh Lord it´s cocaine... 

[Leonie]

R-Type is technical not well done on the CPC.
Star Sabre gives a much better example of how to programm a game like this on the Amstrad.

[arnoldemu]

R-Type may as well be Cocaine. It's a helluva drug... and a helluva game.

yes, visuals let it down, but gameplay is good.

[ukmarkh]

Yes, that's the key... gameplay. I love Star sabre to bits, but to compare it to R-Type on the CPC because visuals let it down is massively missing the point.

R-Type gets the balance just right; and embodies a certain kind of spirit which can appeal to the underdog in all of us. For me R-Type gives the beginner a fighters chance, and rewards the experienced for playing well. Its also bursting with personality, a brilliantly crafted design, and you don't start out with a pea shooter for a weapon. Instead; the enemy is up against it from the word go. However; its depth and incredible variety of identifiable enemies, along with desperate end of level boss shoot outs has placed it as one of the genres greatest works. The arcade original is the definitive version, but the Pc Engine, Amiga, ZX Spectrum and Amstrad 8-bit conversions were highly accurate also.

yes, visuals let it down, but gameplay is good.

[Leonie]

I like the graphic-design, the mood and the gameplay of R-Type too.
But R-Type for the CPC is nothing more than a jerky Spectrum-Port.
A kick up the arse.
The CPC is a machine with 27 Colours and 4 Mhz CPU.
Can´t we expect a little more than a almost-Locomotive-Basic-Shooter like R-Type?

[ukmarkh]

It's not always about graphics, yes I love 'em as much as the next guy... and the CPC could deliver on that front. But don't let it cloud your judgement, we have a classic of a game in R-Type on the CPC, and that's all that matters.

I like the graphic-design, the mood and the gameplay of R-Type too.
But R-Type for the CPC is nothing more than a jerky Spectrum-Port.
A kick up the arse.
The CPC is a machine with 27 Colours and 4 Mhz CPU.
Can´t we expect a little more than a almost-Locomotive-Basic-Shooter like R-Type?

[Gryzor]

I've said it before, I love R-type to bits, even the CPC port (R-Type Leo! That'd have been great... ), so I'll agree with ukmarkh and arnoldemu.

But to compare the two games is very unfair. I mean, the reasons we love R-Type were the product of a massive programming project: all the 'feeling' and 'gameplay' and atmosphere were there from the arcade, and I bet this wasn't coded by a lone programmer in his spare time!!!

[Leonie]

"Dark Fusion" is another game with smooth horizontal scrolling, although it slows down sometimes.
But that doesn´t matter, the scrolling is really fine.
Can someone explain, why horizontal scrolling is more difficult to code than vertical scrolling?

[arnoldemu]

"Dark Fusion" is another game with smooth horizontal scrolling, although it slows down sometimes.
But that doesn´t matter, the scrolling is really fine.
Can someone explain, why horizontal scrolling is more difficult to code than vertical scrolling?

for software scrolling:
- scrolling in y is line-by-line so it is smooth.
- in x, scrolling is normally done by moving bytes. in mode 0 this is 2 pixels at a time, in mode 1 it is 4 pixels and in mode 2 it is 8 pixels.
- scrolling a screen means lots of moving data which uses lots of cpu time. So you need big loops using LDI or similar instruction.

for hardware scrolling:
- at some point in the scroll you will find this problem.
when you want to move to next byte in x (move to right), you can't use a simple increment (e.g. x=x+1, or in asm this is often like this: INC HL).
You will find addresses like this:

C7FF->C000
CFFF->C800

!!!

So drawing sprites is slowed down because you must check for this problem.

- Drawing tiles for scroll is quick, because you can draw 2 bytes at a time (the number of bytes the screen scrolls with hardware horizontal scrolling). You draw a column of the tile at a time.

- hardware scroll is 2 bytes at a time: in mode 0 this is 4 pixels, in mode 1 this is 8 pixels, in mode 2 this is 16 pixels.
You can make this smaller using reg 3, then you move half this speed (mode 0 is 2 pixels).

[ukmarkh]

If you were to use the hardware scroll for a horizontal shooter, you were faced with a nearly unplayable shooter, as the scroll was way too fast. You can play the likes of Killer Cobra to see the results of hardware scrolling.   

[TFM]

If you were to use the hardware scroll for a horizontal shooter, you were faced with a nearly unplayable shooter, as the scroll was way too fast. You can play the likes of Killer Cobra to see the results of hardware scrolling.

Ah no, if you use hardware scrolling in X then it takes roughly 2 seconds to fly through one horizontal screen. Two seconds are an eternity.

And by the way I really don't know what's the problem with scrolling. It's just easy to program it on an CPC. Only with overscan it's a bit more work, but still doable.

[ukmarkh]

Ah no, if you use hardware scrolling in X then it takes roughly 2 seconds to fly through one horizontal screen. Two seconds are an eternity.

And by the way I really don't know what's the problem with scrolling. It's just easy to program it on an CPC. Only with overscan it's a bit more work, but still doable.

Back in the day, 64K was the problem when using overscan.

[MacDeath]

If I remember well Titan was well multidirectionnal scrolled AND "overscan".

[arnoldemu]

If I remember well Titan was well multidirectionnal scrolled AND "overscan".

Not overscan, but was multidirectional hardware scroll.

[MacDeath]

Ok, sorry, not "overscan" but "full screen"...

[Devilmarkus]

Ok, sorry, not "overscan" but "full screen"...

to enable "full screen" press Alt & Enter on your CPC

Whot? no Alt key? So no full screen

[arnoldemu]

I need to clean up some other sources and then I can release the sprite example and also an example that scrolls some tiles.

Source for "rotovision" sprites has been uploaded. Source is not optimised and uses firmware functions, but shows the general method used. (sprites have 3 usable colours, colour 0 is transparent), background has 4 useable colours.

I made the graphics in this example and it shows that i am not a graphic artist

EDIT: See programming section or

http://www.cpctech.org.uk/source/rotospr.asm

[arnoldemu]

to enable "full screen" press Alt & Enter on your CPC

Whot? no Alt key? So no full screen

I see it.. I have a alt key on my cpc 

If the scrolling is too fast in this game press pause/break key.
What you don't have that one?
Too bad..

[TFM]

Back in the day, 64K was the problem when using overscan.

Back in the day, nobody never used overscan, but some demos.

[arnoldemu]

Back in the day, nobody never used overscan, but some demos.

I saw it used for title screens for some titus games, and a few games did use splitting techniques, but you are correct about full overscan.
Problem is it uses a lot of ram on 64k machine.


Well I plan to upload some sources for others to try, so maybe this will kick some people for using overscan more?

[MacDeath]

At the time, in French press, every game with a bigger screen than the average 320x200 was said to be "overscan".

In fact most game that manage to remove 1 part of the border.

I loved those games because most of them had this kind of flavor that tell you this game is not like most others.

Donkey Kong, Arkanoid 1&2, Ghouls and Ghost (too bad the graphics are awfull).
Titan.


I must miss some others.
Shinobi displayed a bit of vertical full screen in the between missions, a tiny detail but it got my attention back in the day.


The magic with this is obvious : most games got a smaller game window.
Dynamic games despite good, were always small screened.

And the speccy porcs in 256x192 (often even less) instead of 320x200...

So when a game managed to remove the barrier of the border, it was a pure magic to me.

Another problem was the lack of its use in intro/cinematic pages.
Because of Cassette/tape and 464... Limited memory and loadings.

But a 6128 should really put a lot of this.

[Gryzor]

And the speccy porcs in 256x192 (often even less) instead of 320x200...

I'll say it once again: I can't, for the life of me understand why they call 256x192 "high-res"... and they go on, and go on praising the Spectrum's "crisp", "clear" and "high-resolution" graphics, whereas in fact it was low-res, mostly monochrome and just plain paleolithic...

Btw, was Donkey Kong really overscan???

[Devilmarkus]

Donkey Kong or Arkanoid weren't "overscan" games.
They only manipulated CRTC registers to aspect of arcade games.
"overscan" means IMO = no visible border!

[Gryzor]

Yes, you're right in that definition, I asked if it was 'overscan' in MacDeath's definition