Xevious

[arnoldemu]

Have you ever wondered why this game is slow and why it has a small play area?

The answer: It uses the firmware for most functions and the scrolling code is very poor.
Would this game had been better if it was a Speccy port?

[Gryzor]

Oh geez, I had never played this before, but I fired it up because of your post. Of course it *was* 1086, but still... bleah. The loading screen is nice, though, in mode 1...

Indeed, I think we have seen speccy ports that have bigger play fields and at least the same speed as that. As it is it looks like a mini-game of sorts, within another game!

[Ynot.zer0]

You awoke an old memory for me with this thread!

back in the late 80's, we actually had the proper arcade game of Xevious.  It was great, very fast, proper joystick and double buttons for fire & bomb, we found loads of hidden places on the scrolling background where you could bomb and get 'extra' features....

so when I saw that a CPC464 version was released, we (myself and my younger brother) clubbed together and purchased the game (it came with a little badge aswell if I remember rightly?)... after waiting for it to load (tape version), it took about 3 minutes to realise that this was made by someone who may or/may not have seen the real arcade game....from a distance!

.... yes, the CPC464 isn't a dedicated games machine processor running 3xZ80 processors, but I remember we were still a little disappointed.

I suppose nowdays, a MAME cabinet would reproduce the original better than a CPC464 version?


If you want to have Xevious as a screensaver: http://www.botchthecrab.com/screensavers/Xevious.zip!

[Gryzor]

Hahaha, man, it really looks NOTHING like the original... I had forgotten about the pesudo-AI avoidance trick the f*ckers do...


MAME is perfect:

[Axelay]

That's interesting.  I never wondered about the quality of the game though, it said US Gold on the front!   I didn't encounter Xevious until late in the CPCs life though, but I'd had a more or less identical experience of disappointment when I purchased 1942.   When I saw Xevious it looked to me to be a reworking of the same game code as 1942 (maybe vice versa, they're both 1986).

As far as a speccy port goes, I'd guess if the speccy port had had as much effort and/or time put into it as the version we ended up with appeared to, it probably wouldn't have made much difference.

[arnoldemu]

That's interesting.  I never wondered about the quality of the game though, it said US Gold on the front!   I didn't encounter Xevious until late in the CPCs life though, but I'd had a more or less identical experience of disappointment when I purchased 1942.   When I saw Xevious it looked to me to be a reworking of the same game code as 1942 (maybe vice versa, they're both 1986).

As far as a speccy port goes, I'd guess if the speccy port had had as much effort and/or time put into it as the version we ended up with appeared to, it probably wouldn't have made much difference.

Hmmm.. this is possible.
I think Slapfight would be the same code... not sure about 1942.. but that is possible.
1942 had some of the source code inside the executable to make it big and try to make you think you were getting more

edit: slapfight is different code. hmmm.. why does it have such a small play area?

[ukmarkh]

I'd imagine the smaller window gave a smoother frame rate... that scrolling does look quite smooth in Slap Fight, and I don't think anyone had ever used 'rotovision' on the CPC prior to Paul Shirley.

It's still a good game, but it just goes to show that the guys at 'FTL' did really well with the Light Force and Shockway Rider game... although their game scrolling wasn't the smoothest, at least it nearly filled the bloody screen, and Light Force was ace. 

[Gryzor]

I actually found 1942 to be pretty playable...

What about the source code thing - was it revealed back then?

[MacDeath]

Ah, the vertical shooters...

Xevious wasn't that bad, I used to like it in fact.
As you know at the times, good vertical shooters weren't that common on CPC...well yes they were maybe after few years...
But no internet = you got the game your friends could give you, and cracked games were not that often found in some towns...

Honestly, I preferred SlapFight...
Also 1942 was good, but old so poorer graphically.

Slapfight was the best port of his generation on cpc.
and its music was really good (Alongside MAgMax...horizontal)

I discovered 1943 and flying shark only recently, and , well, they are very good.
Flying Shark is perhaps one of the best speccy ports available.
But, Mode0 was better for horizontal shooterz, as it seems.

What else ?
Mystical, is it that bad ? I had it on my PC at the time, but CPC port looked quite well done.
Dragon spirit too.
Scramble spirit...ouch!

Back to Xevious, it is quite old even for a CPC production, isn't it ?
As I said, slapFight was a bit better (yet not that fast too) and had interesting weapon system, but Xevious had some interesting stuff, the 2 shoots : one for air and one for ground.

And, well, the small area of play... but as the game was playable and good...you had to do with it.

If I remenber well, even the awesome Dynammic productions in Mode0 with awesome graphics...did had really little tiny small game area...no ?

Game over...and so many more...

Honestly, I am not even sure more than 30% of CPC games used the full display (320x200 or 160x200...)

And "overscan games" were even rarest...
Maybe... 5-6... and a few 3-4 more to include a screen in Overscan (Shinobi text screens are in overscan, lol...)

Arkanoids 1 & 2, Titan, DonkeyKong, Ghouls'N ghost...what else ?

We also have to remember that hose shooters were the only  proper scrolling games in the early era...because they didn't had the choice...
Improovements were done later in that field, thanks to the fact shooters were done..

Msot run & gun games or even platforms didn't really used Scrolling :
Gryzor, Game Over, green Berret, Wizball (as it is some sort of shoot'em up...)

Also the lack of proper GUI in developpment tools made the graphic work harder to fullfill...And most game were to be ddone by a single nerdz in his basement...
This Geek Nerdz coder wasn't a real artist most a time, but a coder only...

[Gryzor]

Ah! Flying shark... so cute, so nice, and quite hard... One of my favs, definitely. Was it an arcade port? I don't remember...

[EDIT] Yes it was. I know what I'm playing tonight on my arcade cabinet!

[khisanth]

Xevious looked like it should be good, but it does a great job of sucking out any possible excitement and fun you might have.

Though its one of the first scrolling vertical shmups so can cut it some slack.

Cool name, crap game.

[Leonie]

Everytime I play Mission Genocide I can´t believe how smooth and fast the scrolling is.
The sprites are also fast and smooth, the playing area is really big.
Why are games with Rotovision so rare?
Isn´t it the perfect vertical scrolling-routine?
What are the disadvantages or restrictions of this routine?
The graphic of Mission Genocide lacks colours, is this maybe "the price" for the good scrolling?
On the other hand, there are a lot of colourless speccy ports with really jerky scrolling.
So I don´t think it´s a matter of the amount of colours.
Can somebody tell me more about it?

[arnoldemu]

Everytime I play Mission Genocide I can´t believe how smooth and fast the scrolling is.
The sprites are also fast and smooth, the playing area is really big.
Why are games with Rotovision so rare?
Isn´t it the perfect vertical scrolling-routine?
What are the disadvantages or restrictions of this routine?
The graphic of Mission Genocide lacks colours, is this maybe "the price" for the good scrolling?
On the other hand, there are a lot of colourless speccy ports with really jerky scrolling.
So I don´t think it´s a matter of the amount of colours.
Can somebody tell me more about it?

The scroll uses the demo technique "rupture"/"splitting" to make the smooth scroll. (crtc register 4 to split the screen into blocks, reg 5 to make the smooth vertical scroll).

This is not always easy to code.

This type of scroll will also use all 16K "video" ram because of the way the scroll works. (the graphics "move" through the 16k memory accessed by the crtc at that time)

Also to make the drawing of sprites fast, they use OR to put them onto the screen and AND to remove them.
Using this method is fast, but you you can't use lots of colours.

This type of scrolling can only be used for smooth vertical scrolling. Smooth horizontal scrolling is not possible with this scrolling method.

Other games used software scroll and smaller screen:
1. easier to convert from spectrum
2. you can use the invisible parts of the "video" ram for storing code and data.

So it make it smooth, they used 2 methods with great results.

EDIT: If you want a code example, I can post one here later?

[ukmarkh]

What else ?
Mystical, is it that bad ? I had it on my PC at the time, but CPC port looked quite well done.
Dragon spirit too.
Scramble spirit...ouch!

Dude, Mystical was half decent, especially on the GX4000. Dragon Spirit was naff, looked good but severley flawed, too hard for one. Scramble Spirit just felt half baked. I tell you a game that could have been fantastic on the CPC... Swiv, but they screwed the speed up. Great game, piss poor port.

Honestly, I am not even sure more than 30% of CPC games used the full display (320x200 or 160x200...)

Probably less if the truth be known, but there are some fine examples like MegaBlasters, 3D Grand Prix, Sorcery +, Xyphoes Fantasy, Zap T Balls, and Mission Genocide.

And "overscan games" were even rarest...
Maybe... 5-6... and a few 3-4 more to include a screen in Overscan (Shinobi text screens are in overscan, lol...)

Arkanoids 1 & 2, Titan, DonkeyKong, Ghouls'N ghost...what else ?

Wern't the Double dragon games by Richard Aplin using overscan?

Msot run & gun games or even platforms didn't really used Scrolling :
Gryzor, Game Over, green Berret, Wizball (as it is some sort of shoot'em up...)

True, but I was playing the arcade version of Gryzor the other night, and the CPC version feels and plays just as good as the arcade original, and that's something to celebrate... fcuk yeah! By the way, Freddy Hardest was a great early side scroller, and I'm not sure when Astro Marine Corps came out, but that was a blinder also.   

Also the lack of proper GUI in developpment tools made the graphic work harder to fullfill...And most game were to be ddone by a single nerdz in his basement...
This Geek Nerdz coder wasn't a real artist most a time, but a coder only...

From the interviews I've done over the months, the general feel from the whizz kids of the 80's was they were never given enough time on the Amstrad stuff.

[Leonie]

If you want a code example, I can post one here later?

Please do that. I want to see the code example right now!
And thank you for the information about Rotovision.
Is it possible to enlarge the Video-Ram somehow?
Maybe some kind of "virtual video ram" that use a part of the main Ram?
The limited colours are the result from the "full" Video-Ram, isn´t it?
So it would be nice to have some more of the golden Video-Ram.

From the interviews I've done over the months, the general feel from the whizz kids of the 80's was they were never given enough time on the Amstrad stuff.

You´re right. So often the CPC had to play the second (or third) fiddle.

[Ynot.zer0]

>If you want a code exmaple, I can post one here later?


Yes please - I'll double that request for getting some know-how on a vertical scroller...


(Is anyone else having issues using Chrome and posting to this forum? font sizing, boldness, odd colours? or is it just me? - oh, and none of those images appear at the top of the postings....)

[arnoldemu]

Please do that. I want to see the code example right now!
And thank you for the information about Rotovision.
Is it possible to enlarge the Video-Ram somehow?
Maybe some kind of "virtual video ram" that use a part of the main Ram?
The limited colours are the result from the "full" Video-Ram, isn´t it?
So it would be nice to have some more of the golden Video-Ram.

 
You´re right. So often the CPC had to play the second (or third) fiddle.

Well I'll upload it tonight now.
I didn't read the forum until this morning (13th).

Enlarge video hardware: Yes, you can make the cpc use 32k of ram for the screen, this is one type of overscan.
But the crtc can never see more than 64k of ram (unless you use that c't memory expansion, but at the moment I don't know if the details of this are fully understood, so I don't know any more).

The limited colours are the result of the sprite drawing and nothing more.

You can make rotovision with full 16-colour sprites if you want.

[arnoldemu]

Well I'll upload it tonight now.
I didn't read the forum until this morning (13th).

Enlarge video hardware: Yes, you can make the cpc use 32k of ram for the screen, this is one type of overscan.
But the crtc can never see more than 64k of ram (unless you use that c't memory expansion, but at the moment I don't know if the details of this are fully understood, so I don't know any more).

The limited colours are the result of the sprite drawing and nothing more.

You can make rotovision with full 16-colour sprites if you want.

http://www.cpctech.org.uk/MESS2.asm

This code has 2 static blocks (top and bottom) and a smooth scrolling middle part (using register 5).
Works on crtc type 0. Essentially it demonstrates the smooth vertical pixel scrolling shown in Rotovision.

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

[Leonie]

Are there any similar "waterproof" scrolling-routines like Rotovision for smooth horizontal-scrolling?


PS: I like the scrolling of "Star Sabre" very much, and the smooth sprites of "Dead On Time".

EDIT: The sprites of "Star Sabre" are, of course, also very smooth.
Does somebody know the blocky "R-Type"?
Star Sabre is so much better!

[ukmarkh]

http://www.cpctech.org.uk/MESS2.asm

This code has 2 static blocks (top and bottom) and a smooth scrolling middle part (using register 5).
Works on crtc type 0. Essentially it demonstrates the smooth vertical pixel scrolling shown in Rotovision.

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

Better than R-Type... really? I'm amazed anyone would think that?

[Gryzor]

Presumably Leonie was talking about the sprite smoothness?

[arnoldemu]

Are there any similar "waterproof" scrolling-routines like Rotovision for smooth horizontal-scrolling?


PS: I like the scrolling of "Star Sabre" very much, and the smooth sprites of "Dead On Time".

EDIT: The sprites of "Star Sabre" are, of course, also very smooth.
Does somebody know the blocky "R-Type"?
Star Sabre is so much better!

I don't think there are any "waterproof" scrolling methods.

There are a few methods, but each has their problems:
1. reg 3 trick. This can be used to make the scrolling byte-by-byte. But the disadvantage is that it doesn't seem to work the same for all crtc, and also doesn't work with MP-1/MP-2 modulator.

2. have 2 screens, one has "shifted" graphics compared to the first. Great if the scrolling is only in one direction and always moving. If the scrolling stops or is multi-directional it is not so easy. I think Star Sabre uses this method.

Well R-Type vs Star Sabre... no competition here. R-Type is a game made on spectrum and transferred to cpc without using cpc hardware scrolling and without adjusting to the cpc's abilities.

Star Sabre is made and designed for cpc.

[arnoldemu]

http://www.cpctech.org.uk/MESS2.asm

This code has 2 static blocks (top and bottom) and a smooth scrolling middle part (using register 5).
Works on crtc type 0. Essentially it demonstrates the smooth vertical pixel scrolling shown in Rotovision.

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

This code is not ready for a game.

Really to be ready for a game the split and r5 scroll need to be done using interrupt routines. The code currently waits for interrupt with HALT and then does split. For a game this would waste too much cpu time waiting around.

[Leonie]

Presumably Leonie was talking about the sprite smoothness?

R-Type VS Star Sabre:

Yes, I mean the sprites and especially the scrolling.
The scrolling of R-Type works almost block by block.
It looks like there is a custums check for each block on the right side of the screen.

[ukmarkh]

Well R-Type vs Star Sabre... no competition here. R-Type is a game made on spectrum and transferred to cpc without using cpc hardware scrolling and without adjusting to the cpc's abilities.

Star Sabre is made and designed for cpc.

Shut your hoar mouth