Thanks... the only place on this screen that the sprites can't go are
the far left and far right pixels of the playfield, which are the
walls of the five-level thing... so would I just remove the smallest
and largest values from posLst and make that work?
Also, in your code you reference the posLst, list of horizontal
positions... what would this look like? I don't understand how to make
such a list in my code.
Thanks for all the help, I'm now on my way to having a game, or at
least a moving sprite :)
~ Kevin
On Wed, 6 Oct 2004 09:23:49 +0200, Thomas Jentzsch <tjentzsch@xxxxxx> wrote:
> Kevin Lipe wrote:
> > What would be the best way to position sprites and such in a kernel
> > for the game concept I was talking about in the above thread? Attached
> > is the code I've got right now, which just makes a really pretty
> > playfield and nothing else.
>
> I suppose you want to reposition your sprites *inside* the kernel, right?
>
> The most simple code for this would look like this:
> ldx index ; the current sprite index
> lda posLst,x ; a list containing all horizontal positions (0..159)
> sta WSYNC
> ----------------
> sec ; 2
> .wait:
> sbc #15 ; 2
> bcs .wait ; 2/3
> eor #$07 ; 2
> asl ; 2
> asl ; 2
> asl ; 2
> asl ; 2
> sta HMP0 ; 3
> sta.w RESP0 ; 4 @23+n*5
> sta WSYNC ; 3
> ----------------
> sta HMOVE
>
> This is however a general solution, which allows positioning sprite 0 across
> the whole screen and uses one whole scanline
>
> For your kernel you may need something more specialized, e.g.
> - objects cannot move accross the whole screen, so you can free some
> cycles for other kernel stuff
> - you don't have that much free time inside your kernel, then you should
> calculate the fine and coarse positioning values outside the kernel. This
> saves a few cycles and allows additional tricks (e.g. two different codes
> for positioning objects on the left and right, giving you more free cycles
> for other stuff)
> - ...
>
> So this can get quite complicated later, but for a start I suppose using
> something like the code above.
>
> Have fun!
> Thomas
> _______________________________________________________
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