I was thinking of writing super Mario bros for the BBC, but people didn't seem too impressed with turning their monitors on their side just to get smooth pixel scrolling, so I had a flick through MAME to find something that wouldn't invalidate your guarantees!

After a trip down memory lane I decided on carnival as it looked like a good fit for the BBC and the old Acornsoft version was a big disappointment back in the day

I have been unwell for quite a while now and so haven't made much progress. I thought posting what I have might generate a little encouragement

Richard

Keys are Z, X (left, right) and B to fire.

It is still very early days and I can't spend much time on it as blurred vision and headaches are a couple of my simptoms.

Here is a short video, there are a few broken bits:

Hitting targets is pixel perfect and scoring works, but the wrong bit of screen is cleared and the wrong (differently wrong!) target (or part of) is removed from the conveyor.

Running out of bullets doesn't stop you shooting or end the level.

I haven't made the left facing sprites correctly, so the middle row of targets leaves trails (but at least you get an idea of how it is coded).

It runs in mode 1, so I don't have enough colours to match the original.

I ripped the sprites from the arcade roms which I happen to have lying around (from my old days in the arcades), but am open to maybe chuckie egg ducks or bbc owl owls and could add basic animation at no extra cost.

Looks really good. Mode 1 always looks great so it's a shame more games didn't use it.

I've only just seen the Mario Bros thing - excellent work! Hope something can come of it in the future.

Sorry to hear you've been unwell. Hope your health picks up soon.

Best wishes,

Rob

Thanks Rob, I was feeling a bit better tonight, so I have fixed hitting the top and bottom rows, including removing the target, scoring etc
I still have over 1/2 a 50Hz frame left, so should be able to get the pipes in and have no flickering - the falling ducks might be a stretch, but as long as you get them first not flickering can be part of the reward.
I never did any of the sound for Jeltron, so adding the music is also going to be interesting, still the AY3 in carnival is similar to the beeb's sound chip.
I was planning a two player simultaneous side-by-side version in full-screen, but I also narrowed the screen to 32 (64 half chars) by 32 to simplify the code so that is gone, but it does give another 4K.


EDIT - display screen shot

Love surprises like this!

It already feels (and looks) better than Acornsoft's conversion.

I do like the idea of theming the graphics to suit e.g. BBC owls and other recognisable Acorn sprites! (Maybe include a 'cheat' mode to revert to arcade graphics?).

And if you can produce a 2-player version that would be exquisite, as there are barely any decent head-to-head 2-player games on the Beeb/Elk.

I'd always hoped we see new conversions of early coin-ops whereby either a) the Acorn version didn't do the original justice or b) no Acorn version existed. Here's hoping this is the beginning of a trend!

Sorry to hear you're unwell - from a selfish point of view I hope it doesn't prevent you from making progress on Carnival, 'cause it has the makings of being a corker!

Thanks Dave, didn't feel too bad tonight, so added the pipes bonus box and decremented it - I never realised that it went down every time you fired and didn't hit a pipe - there was a lot more strategy that I remembered.

As a reward for the encouragement, here is a slightly newer version and some very ugly source code!

Hi there - Looks nice! Very smooth animation in Mode 1.

What technique are you using to achieve that? I ask, as I've just abandoned the idea of writing a game in mode 1 as the routine I use moves pixels in byte increments on the x plane... i.e 4 pixel increments.. so animation doesn't look smooth.

Meantime.. I like your scrolling idea for a platformer - i.e rotating the physical monitor. I'd be happy to do that to see smooth scrolling on the Beeb on a complete game.

edit: sorry jbnbeeb, I missed your post - I am just using one copy of each sprite per pixel, so they each have four copies in each direction, turning the 8 pixel wide sprites into 3 characters (12px), this also allows them to be "self erasing" as they move along, saving time as with a black background, you only have to STA and don't need any masks etc. This also means that you can add a four frame animation for no extra space or time

I got a few more hours today and wrote a converter to map and draw the pipes, added BONUS scoring and have hidden the middle row for now until I can tidy up the gfx. you can't hit the pipes yet, but apart from having to add relocation on load as memory is running low, I think I can still get there.
Here is a Youtube video as my other links aren't quite as active as I had hoped - I guess that's what you get for a port, rather than an original game.
http://youtu.be/63_h1hCxSRE Sorry, can't seem to get the hang of embedding!

Hi,
I'm using the same technique as you for a game I'm writing (a 2 player dogfight plane game) re sprites. However, I need shedloads of sprites as I have 8 directions for a plane to fly in, and 4 sprites per direction.. = 32 sprites per plane. So I am using Mode 5.

I do wonder about using shadow mode 1 on a Master.. I don't own one (though I will end up buying one eventually) - but I could test on B-Em. The only trouble is that this would limit the amount of real hardware it could be played on. I'd definitely consider it if I could do it with minimal modification to the Mode 5 code.

Anyhoo - back to your game!! It's looking good. Keep us posted as you're going along. Also, definitely interested in your platform /rotate monitor game idea. It'd be great to see that developed!

Is it possible to store the graphics data in sideways ram? This might make it less incompatible as all beebs can use it.

EDIT - Carnival is looking great too!

Hi tricky,

nice game, smooth movements and looks exactly like the MAME carnival ..... nice job !!

Greetings
Kees

Tonight I have added hitting the pipes and their bonus.
I have added another youtube video (2 mins) of me getting a "hi-score"
Screen shot, source code and a disc image attached if anyone fancies a challenge.
It's not exactly hard as there are no falling ducks and even if you run out of bullets, you don't stop firing



http://youtu.be/4kLQwGHUOfM

The original actually moved half a line (or half of the pipes) at a time and moved it 2 pixels, that looked a bit ugly to me; I am just hoping that I won't run out of memory and have to go back and do the same thing!

Haven't had much time over the last few days and been poorly today, so have only fixed the middle row in the last three days:

I can't get to my Beeb at the moment, please could someone try the image on real hardware for me and let me know if it is OK?

EDIT: I still have just over 2K left and about 3/4 of a frame of time, so memory is looking a bit tight, but the are still some less-memory, more-time changes I can make.

Great work and it seems to work fine on my M128. Can try it on other machines if you wish...

Thanks, that is good news.

I have added generating the [5]s, [10]s and ducks, and you can't shoot when you run out of bullets.

I'll try and get falling ducks in today, but more likely by monday.

Ducks now fall and eat bullets (no eating anim' yet), you can't shoot them yet, so it is a bit tough!

Down to 1K, so not looking good for bears and music, but I can probably find some more room somewhere.

EDIT: After a reshuffle, 3K left, so not so bad.

Looking good so far, and very smooth to play as well.

Just scored 1490 before running out of bullets!!

It's incredible how quickly this is being developed ... can't be much left to do now, surely?

As I mentioned above, it's fast and smooth to play - and it looks the spit of the arcade game.

Glad you've managed to free up some extra memory - hopefully that'll mean you'll be able to retain the music (as for me that's half of the game!).

Speaking of audio, when you come to implement the sound effects - will you be able to use 'channel 0' (white noise) for the firing noise - as per the arcade version?

Lastly it's a shame we lose the extra cyan colour from the original (damn Mode 1!) ... is there a way of using interrupts to achieve the extra colour? Even if it was just for the high score and bonus figures at the top, I reckon the extra splash of colour would make a big difference.

Failing that, maybe consider tinkering with the palette to replace white with cyan, as I think it looks better this way ... opinions?

Speaking of developing quickly

You can now shoot falling ducks, they eat your bullets, the level ends when no targets (or pipes) are left, you get a +50 bonus for each bullet left and then the next level starts with more ducks, faster generating ducks and, well you will see!

There is a bug, where you can hit the side of a falling duck, which leaves a bullet behind and means you can't finish the level - I will try to fix this next!

New disk image attached. ~2.3 KB remaining

It is quite easy to add timers to change colours for various sections of the screen as you go down - eg swap red+yellow for cyan+green in the top section or change the red targets for another colour. I haven't added any timer code to this game yet, so there is only vsync (16 pixels off the bottom of the screen).