Uridium on the CPC with hardwarescrolling

[ivarf]

Looking at
8-bit battles Uridium
8-bit battles uridium - YouTube

I see 4 versions, The Amstrad CPC, BBC, Spectrum and C64. Ranking them for smootness and speed I get this list:
1. C64
2. BBC
3. Spectrum
4. Amstrad CPC

The BBC-version looks really good, fast and smooth and it uses the same gfx-chip as the CPC - the CRT.

A new version that uses the CRT could be really good! Anyone?

[TFM]

Play it on a real CPC and CPC is first at full speed. 

[ivarf]

The BBC-version looks really good, fast and smooth and it uses the same gfx-chip as the CPC - the CRT.

A new version that uses the CRT could be really good! Anyone?

I meant the 6845 Cathode Ray Tube Controller (CRTC)

[arnoldemu]

Looking at
8-bit battles Uridium
8-bit battles uridium - YouTube

I see 4 versions, The Amstrad CPC, BBC, Spectrum and C64. Ranking them for smootness and speed I get this list:
1. C64
2. BBC
3. Spectrum
4. Amstrad CPC

The BBC-version looks really good, fast and smooth and it uses the same gfx-chip as the CPC - the CRT.

A new version that uses the CRT could be really good! Anyone?

In these battles the CPC almost always comes last because of the poor speccy ports and because less care was taken with the coding.

Yes uridium scrolling could be done with hardware and it would be equally as good as the bbc.

[MacDeath]

Yes, those speccy ports almost never help when they are the main choices in those 8bit battle videos.

[TFM]

Sorry, but the BBC scrolling is really jerky. IMHO CPC and C64 have good scrolling. CPC version is my clear favorite here.   

[MacDeath]

BBC is in pseudo mode0 while CPC is in mode1...
makes a difference.

good point for the CPC version : coloured sprites with no colour clashes, hence still somewhat better then Speccy original.
sadly the 1bpp background doesn't help for collisions.

[arnoldemu]

flame me if you want, but using mission genocide, or ghosts n goblins type sprites would work well for a rethought cpc version.

yes there wouldn't be as much colour, but believe me when I say it would mean a faster frame rate.

I am planning to write a detailed article about cpc's hardware scrolling, including plotting sprites and erasing them etc.

[redbox]

I am planning to write a detailed article about cpc's hardware scrolling, including plotting sprites and erasing them etc.

Awesome, that would be a great read 

[arnoldemu]

Awesome, that would be a great read 

I started the doc and it is attached.

It covers the basic points at the moment.

[arnoldemu]

updated.

[arnoldemu]

And again with comments about Plus.

So you can understand what extra help it gives us.

[arnoldemu]

final update for tonight.

[MacDeath]

flame me if you want, but using mission genocide, or ghosts n goblins type sprites would work well for a rethought cpc version.

I think the name is "dual playfield" and yes, this technic has some nice potential.
Especially with the PLUS :
=rasters so you may get some vertical gradiants/additional colours...
=Hardware sprites which would had even more colours.

May be great to have some demos using this a bit.

[AMSDOS]

I've only played the CPC version of this game since AA gave it away on their Covertape, but personally I don't have any problems with the game and am even surprised that someone has got a problem with the scrolling. Ok the game looks like the Spectrum version though it is done in MODE 1 with the enemy in various colours which help make things stand out, to me the CPC version looks quite slick.


The c64 version has some nice features, though I think suffers with it's bizarre colour scheme. The BBC version I don't know where to begin with that, I thought it looked very scrappy, the scenery is ill defined I think due to the low-res graphics and it looked like the Collision Detection wasn't working properly, unless they were cheating 

[Carnivius]

Scrolling never bothered me, just the graphics.  CPC is capable of so much more than barely different Spectrum ports even in Mode 1.  I still prefer Mode 0 for horizontal scrolling shooters anyway.

[Gryzor]

@arnoldemu : can I make this into a wiki article?

[arnoldemu]

@arnoldemu : can I make this into a wiki article?

yes.

[arnoldemu]

I will update the doc when you've put it up on the wiki. I've added some more information.

Also, if you're interested in the coding side of this please look at the new coding examples.

New examples for drawing a sprite on a hardware scrolling screen (including calculating the screen address from sprite coordinates), plus how to avoid the problem area when scrolling vertically or horizontally. It can be avoided if you scroll both horizontally and vertically but I think there are more restrictions on screen size.

I have also added an example to show chunky scrolling, msx1 style.

I have started to write an example to show push scrolling and realised that making a good push scroll is quite an art, and involves a lot of testing and tweaking. I think this is why some games don't do it well. I'm not yet sure if a push scroll avoids/minimises the problem area at all.

[Gryzor]

Thanks, I'm preparing the article' it's a long one to do because of the line breaks and everything, so I'm doing it line by line... will let you know when it's done.

[AMSDOS]

Scrolling never bothered me, just the graphics.  CPC is capable of so much more than barely different Spectrum ports even in Mode 1.  I still prefer Mode 0 for horizontal scrolling shooters anyway.

I think that's a fair observation, it's a great game which suffers from the Spectrum graphics, the graphics only need some reconstruction. Yes the game plays on a Spectrum screen, but so does Rainbow Islands, which has scrappy scrolling, even Edd the Duck has better Scrolling. 

[ivarf]

I think that's a fair observation, it's a great game which suffers from the Spectrum graphics, the graphics only need some reconstruction. Yes the game plays on a Spectrum screen, but so does Rainbow Islands, which has scrappy scrolling, even Edd the Duck has better Scrolling. 

This is a game where the BBC version in my opinion has faster and better scrolling than the CPC version. Other CPC games may have worse scrolling than Uridium, my point was that the CPC could have had the same scrolling as the BBC. Same graphic chip. Maybe a 6502 instead of the Z80 would have been better after all. The BBC coders could have jumped over to the Amstrad CPC. We would still get ports, but from the C64 instead.

[arnoldemu]

This is a game where the BBC version in my opinion has faster and better scrolling than the CPC version. Other CPC games may have worse scrolling than Uridium, my point was that the CPC could have had the same scrolling as the BBC. Same graphic chip. Maybe a 6502 instead of the Z80 would have been better after all. The BBC coders could have jumped over to the Amstrad CPC. We would still get ports, but from the C64 instead.

I agree. The only difference between BBC and CPC is that I think when the BBC scrolls horizontally it's in 1 byte units compared to 2 bytes on CPC. The way the BBC maps the memory addresses to the screen is different.

On CPC, incrementing by a byte moves accross one byte to the right. I believe on the BBC it moves 1 line down. 8 increments moves down 8 lines and then to the start of the next crtc char to the right.

But you are correct, same CRTC, same features, and the BBC has to draw and erase it's sprites by software methods.
I think it's 2Mhz 6502 means it ends up faster than the CPC, but it's native display size is bigger (20K or so compared to 16K).

I think Uridium was meant to be fast and smooth and responsive. On the CPC the current version needs a little bit more speed and tweaking.


BTW, I am continuing with my "journey into CPC hardware scrolling" with more examples and more documentation.
More updates soon. (It's also helping to 1) cement my knowledge and help he with the beat em up game 2) I am actually testing some of the methods I've seen being used for myself to verify and show others what can be done).

[AMSDOS]

This is a game where the BBC version in my opinion has faster and better scrolling than the CPC version. Other CPC games may have worse scrolling than Uridium, my point was that the CPC could have had the same scrolling as the BBC. Same graphic chip. Maybe a 6502 instead of the Z80 would have been better after all. The BBC coders could have jumped over to the Amstrad CPC. We would still get ports, but from the C64 instead.

Well by all means if you're unsatisfied with the CPC version of Uridium, perhaps you should recode it so it's in MODE 0 and limit the amount of detail in the scenery. The BBC version is faster, though it also appears scrappy, maybe that's an emulation flaw or maybe it's a YouTube flaw (though YouTube wasn't showing any signs of it on the CPC version).

You could argue your "what if's" all night regarding a 6502 Amstrad, but the fact is it's Z80, you wouldn't be able to change that until someone makes a 6502 ROM adaptor for it. 

[Carnivius]

Well by all means if you're unsatisfied with the CPC version of Uridium, perhaps you should recode it so it's in MODE 0 and limit the amount of detail in the scenery.   

But there's hardly any detail to begin with.  And it uses a dither pattern the same size as Mode 0 pixels to pretend there's another shade of blue on those large ships too.


Am tempted to do a full mock up shot of the Amiga's Uridium 2 onto CPC like I started with these ships a few months ago.  I don't really have time though.