A83: Background routine...


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A83: Background routine...



I know my tutorials are slow coming out, but senior year + college apps + ThinkQuest + Monopoly (programming) + chicks...um, tutorials are waaaay down there :)...anyway, here is my Background tutorial.  Thanks to Movax (ey?)....

Tutorial 39: Scrolling Background.
More Game Techniques.
Introduction.
Well, after attempt after attempt at finding or writing a decent scrolling routine.  I'm talking to Movax, and he's like "Hold on", 5 minutes later I'm running a perfect scrolling routine he'd just written (don't you hate people like that! =Ž).  Thanks a lot to Hannes "Movax" Edfeldt.

New Commands.

_getk - I've covered this briefly before.  Here's the formal cover…like BASIC getkey.  Returns value of the key to OP1.  Values are shown the Ti-manual.


The Code.

 ld    hl,picture ;Load your pic.
 ld de,PLOTSSCREEN
 ld bc,768
 ldir
 call  _grbufcpy_v

loop:
 call _scrollright
 call _grbufcpy_v

 call    _getk    ; Key to OP2.
 call    _op2toop1
 call    _convop1
 cp  45 ; If clear…
 jp      nz,loop ;
 ret



_ScrollRight:
ld de,12
ld hl,8e29h-1
ld b,64 ; 64*12=768 bytes to rotate
_loop1:
push hl ; Test if there's a bit to wrap around
add hl,de
ld a,(hl)
and 00000001b
sub 00000001b
ccf
pop hl

inc hl ; We'll waste space here to gain some speed
rr (hl)
inc hl
rr (hl)
inc hl
rr (hl)
inc hl
rr (hl)
inc hl
rr (hl)
inc hl
rr (hl)
inc hl ; We'll waste space here to gain some speed
rr (hl)
inc hl
rr (hl)
inc hl
rr (hl)
inc hl
rr (hl)
inc hl
rr (hl)
inc hl
rr (hl)

djnz _loop1

 ret

picture:
;Put your picture here.

.end
END


Conclusion.
Thanks again to Movax for this routine!  This should help all of you game freaks out there!  If you come up with a better routine that scrolls left/right, up/down, or all directions, please contact me!  Thanks.

{button , Klink(Scrolling;Movax;Graphics)} Related Topics.

Addition:  if you come up w/a routine that is *well documented* contact me :)...

Later,

James Matthews (matthews@tkb.att.ne.jp)

ICQ: 7413754
http://home.att.ne.jp/gold/tomcat21/index.html
http://library.advanced.org/18242/


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