EnigmA Amiga Run 1996 June/EnigmA AMIGA RUN 08 (1996)(G.R. Edizioni)(IT)[!][issue 1996-06][EARSAN CD VII].iso/earcd/amos/amsls496.lzh/AMOSLIST/[e-mail]_Thu Apr 25 22:05:38 1996.msg

Internet Message Format | 1996-05-01 | 6KB

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Date: Thu, 25 Apr 96 21:14:52 GMT
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From: Paul Burkey <[e-mail]>
To: [e-mail]
Subject: Re: Bobs on scrolling maps
Status: RO
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Tom Davies wrote:-

>Im am very surprised to read all this absolute junk everyone is spouting
>regarding bobs and scrolling maps !!! What planet are you guys living on
>!!!

I've never seen a good 32 colour scrolling game with plenty of bobs written
in AMOS but I'm sure you could do it with a lot of work. I did see a game
that did scroll pretty well and it was written in AMOS but I soon noticed it
was using a 16 or maybe even 8 colour screen :(

>Setting up a tile based system to scroll with aint easy but I saw a routine
>in CU Amiga a few years back that was absolutly superb and does it really
>well.

Maybe you could upload it to Aminet or send us a copy of the routine. I'm
interested in seeing how well it works. It will have to be smooth with at
least 32 colours because this is the the very lowest spec for a game these
days. and it must also leave plenty of vbl time for bobs and stuff... How
fast does it go without the 'Wait Vbl' command? And how wide/tall is the
scroll view and how many colours... The scroll routine has to take up less
than 1/4 of the time of the vbl as a good game relys on plenty of AI and
gameplay.

>Decide on the size of blocks... I went for 32*50 on a 200 lines
>screen.

32x50!!! Thats a bit big isn't it? That means only 4 blocks high on each
screen? Are you sure? I'd have expected 32x32 to be the very bigest you'd
go for although 16x16 gives you more complex maps. Just look at Alien Breed
and try to imagine it, if it was done in 32x50 blocks.

>Open a screen about 750 by 200 .Offset it 32 pixels and paste down all the
>icons on the screen. Then write a scroll routine that dies this :-
>
>1. Offsets the screen.
>2. Every 32 pixels draws 1 block to the LEFT of the viewport.
>3. At the end of the scrreen, Whip it back the the start where it will be
>   waiting nice and neat as youve drawn the icons previously with paste icon.

Don't you need to draw your icons on both the right and the left? Your method
looks quite similar to the way I do it but I'm sure you meant to have Icons
pasted on both ends so that you end up with two copies of the screen for when
you flip it back... This sin't a critisism, I'd just like to see what other
methods are used for this sort of stuff.

I'd also recomend you go for the slightly better version that I've used where
instead of waiting for every 32 pixels, you stagger your pasting over the 32
pixel movement so if you have 16 blocks to paste down, you paste 1 block every
2 pixels.... This avoids that nasty bit of pasting-it-all-in-place in the same
frame.

>At the start of the loop, add a bob clear. Move your bobs around as you
>please. If you are gonna paste icons here as well, you need to do so twice,
>adding a screen swap after each redraw :-
>
>for p=1 to2
>Draw icons
>screen swap
>next
>
>this ensures both screens "get it". After, at the end of the loop, Update
>bobs, swap screen and wait Vbl... or maybe in another order.

Are you using Amal to move you bobs? I just wondered how you get amal to detect
where your screen offset is and when you flip your screen back?

>This is the way to do it, as my game DARKNESS shows. Its nearing completion
>and i think it REALLY pushes AMOS to the limits - you'll be able to see it
>soon when I realease the beta test version for you lot to play with.

I *would* like to see it, as I feel this sort of sharing of ideas is good for
our programming skills. Even if I don't see the source code, I always love to see
good results from AMOS. It's just a pitty you can't do a 256 colour version :(

Cheers,

Paul


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