[stella] WIP: Salmon Run: Asymmetrical Playfield

[Thom Cherryhomes]

okay, I'm going to do some thinking and experimenting.... i will keep
you guys posted.. Thanks so much for the help.

This is proving to be a challenge..hehe...

-Thom


On 3/14/07, bob.montgomery at thomson.com <bob.montgomery at thomson.com> wrote:
> Hi Thom,
>
> >The problem with dealing with precisely 22 lines of playfield data
> >(including the top and bottom rows that shrink/grow depending on where
> >we are in the smooth scroll), is that in order to scroll without doing
> >excessive compares, I need not only some breathing room (to be able to
> >generate 2 to 4 lines ahead of the screen), but i want to easily be
> >able to constrain my counting using just an AND .....
> >
> >This pushes my memory constraints to 32 x 4 if I choose to do this, or
> >am I missing something?
>
> Well, obviously 32 x 4 bytes of RAM won't work on a stock cartridge.
> You could either go to a Superchip design, or...
>
> >i want to easily be able to constrain my counting using just an AND
>
> Unless I'm missing something, you'll just need to drop this wish. ;)
>
> I'd suggest using exactly 22 lines of playfield data and coding without
> the easy count constraints and without the breathing room.  Or if the
> breathing room is absolutely necessary, use 26 x 4 byte of RAM.  That's
> pushing it, though.
>
> Another option: store the river in RAM as a series of 22(+) bytes, one
> for each row, each a lookup to a table of PF values.
>
> This complicates your kernel, since you have to do something like this
> between every row:
>    ldx Index
>    lda RiverRAM,X
>    tax
>    lda RiverLookupPF1,X
>    sta PF1Temp
>    lda RiverLookupPF2,X
>    sta PF2Temp
>    lda RiverLookupPF3,X
>    sta PF3Temp
>    lda RiverLookupPF4,X
>    sta PF4Temp
>
> and then your kernel would look something like this...
>
>    ...
>    lda PF1Temp
>    sta PF1Temp
>    lda PF2Temp
>    sta PF2
>    lda PF3Temp
>    sta PF1
>    lda PF4Temp
>    sta PF2
>    ...
>
> Saves you cycles in the kernel and a ton of RAM, though it will make for
> a messy kernel, since loading PFxTemp will probably have to be spread
> over several lines, since you will be displaying sprites and an asym
> playfield all the while.  Certainly doable, though. :)
>
> Also limits you to 256 different river rows, but that's probably enough,
> I would guess.
>
> -bob
>
>
>
>
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