Re: A86: Re: box drawing
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Re: A86: Re: box drawing
no, it wouldn't. but this would.
i wrote it actually just before the question was posted. it's probly not
terrible optimized, you have to decode the screen location before you
call it, and it only works with boxes that start and end on a multiple of
8 pixels across.
-josh
; hl->screen start address
; b=rows (not inc top&bottom)
; c=bytes wide
draw_box:
ld a,$10
sub c
ld e,a
ld d,0 ; de=width of area outside of box
ld a,$ff
push bc
ld b,c
call draw_horiz_line
pop bc
add hl,de ; next line
ld a,c
dec a
jr z,draw_box_bytewide
dec a
jr z,draw_box_nomiddle
draw_box0:
ld a,$80
ld (hl),a
inc hl
xor a
call draw_horiz_line
ld a,$01
ld (hl),a
inc hl
add hl,de
djnz draw_box0
ld a,$ff
ld b,c
call draw_horiz_line
ret
draw_box_bytewide:
ld a,$81
inc de
draw_box1:
ld (hl),a
add hl,de
djnz draw_box1
ld a,$ff
ld (hl),a
ret
draw_box_nomiddle:
ld a,$80
ld (hl),a
inc hl
ld a,$01
ld (hl),a
inc hl
add hl,de
djnz draw_boxnomiddle
ld a,$ff
ld (hl),a
inc hl
ld (hl),a
ret
; hl->screen start address
; b=bytes wide
; a=pattern
draw_horiz_line:
ld (hl),a
inc hl
djnz draw_horiz_line
ret
On Sun, 24 Oct 1999 18:40:51 -0600 "David Phillips" <david@acz.org>
writes:
>
>But it wouldn't fill the center with white, would it?
>
>Btw, I remembered that the game Jezzball does have horizontal and
>vertical
>line drawing routines, if you want some code to look at, although
>it's
>pretty bad (because I looked for a long time for some before writing
>my
>own...which were on my HD when I reformatted or else I'd post them).
>
>> there has to be a built in routine somewhere to draw a box because
>it's
>> used for the ZOOM:BOX feature.
>
>
>
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