dos33fsprogs/demos/second/part04_chess_shapes/interference.s
2023-10-29 20:27:56 -04:00

269 lines
3.8 KiB
ArmAsm

; Interference Pattern
; a really bad hack up of some existing code I had
; don't have time to make something better
;================================
; Clear screen and setup graphics
;================================
interference:
bit SET_GR
bit FULLGR ; make it 40x48
bit PAGE1
; bit LORES ; put this off so draw before flip
lda #0
sta FRAME
lda #4
sta DRAW_PAGE
draw_oval_loop:
inc FRAME ; increment frame
ldx #47 ; YY from 47 downto zero
create_yloop:
txa
;================================
; plot_setup
;================================
plot_setup:
lsr ; shift bottom bit into carry ; 2
tay
bcc plot_even ; 2nt/3
plot_odd:
lda #$f0 ; 2
bcs plot_c_done ; 2nt/3
plot_even:
lda #$0f ; 2
plot_c_done:
sta mask_smc2+1 ;
eor #$FF ; 2
sta mask_invert_smc1+1 ;
lda gr_offsets_l,Y ; lookup low-res memory address ; 4
sta gbasl_smc1+1
sta gbasl_smc2+1
lda gr_offsets_h,Y ; 4
clc
adc DRAW_PAGE ; add in draw page offset ; 3
sta gbasl_smc1+2
sta gbasl_smc2+2
;==========================================
;===========================
; calculate for each XPOS (Y) on ROW (X)
ldy #39
create_xloop:
; lda #128
lda FRAME
sta SUM
tya ; XX
jsr calcsine_div2
txa ; YY
adc FRAME ; ADDED
jsr calcsine
; X (YY) is in SAVEX
clc
sty SAVEY ; XX
tya
; PATCH?
adc SAVEX ; XX + YY
adc FRAME ; ADDED
jsr calcsine_div2
; jsr calcsine
; clc
; adc FRAME
lsr ; double colors
and #$7 ; mask
tax
lda colorlookup,X
sta color_smc+1
; tya
; pha
;================================
; plot1
;================================
plot1:
mask_invert_smc1:
lda #$ff ; load mask ; 2
gbasl_smc1:
and $400,Y ; mask to preserve on-screen color ; 4+
sta COLOR_MASK ; save temporarily ; 3
color_smc:
lda #$FF ; load color ; 2
mask_smc2:
and #$FF ; mask so only hi/lo we want ; 2
ora COLOR_MASK ; combine with on-screen color ; 3
gbasl_smc2:
sta $400,Y ; save back out ; 5
;=================================
; pla
; tay
ldy SAVEY
ldx SAVEX
dey
bpl create_xloop
dex
bpl create_yloop
lda DRAW_PAGE
beq flip_to_2
bit PAGE2
lda #0
beq done_flip
flip_to_2:
bit PAGE1
lda #4
done_flip:
sta DRAW_PAGE
bit LORES ; here so first flip happens after having drawn
;===================================
;===================================
;===================================
; try patching
lda FRAME
and #$10
bne do_patch1
undo_patch1:
lda #$EA ; nop
bne done_patch1 ; bra
do_patch1:
lda #$4A ; lsr
done_patch1:
sta patch1
;===================================
lda KEYPRESS
bmi done_interference
jmp draw_oval_loop ; bra
done_interference:
bit KEYRESET
rts
;=============================
;=============================
calcsine_div2:
; no LSR = zoomed out
lsr ; one LSR = zoomed in on oval
patch1:
nop ; two LSR = more zoomed in
calcsine:
stx SAVEX
and #$3f
tax
rol
rol
rol
bcc sinadd
sinsub:
lda #0
lda SUM
sec
sbc sinetable-32,X
jmp sindone
sinadd:
; ldx FRAME
lda SUM
clc
adc sinetable,X
sindone:
sta SUM
ldx SAVEX
rts
colorlookup:
; pink
.byte $55,$11,$33,$bb,$ff,$bb,$55
.byte $00
sinetable:
; this is actually (32*sin(x))
.byte $00,$03,$06,$09,$0C,$0F,$11,$14
.byte $16,$18,$1A,$1C,$1D,$1E,$1F,$1F
.byte $20,$1F,$1F,$1E,$1D,$1C,$1A,$18
.byte $16,$14,$11,$0F,$0C,$09,$06,$03
;.byte $00,$FD,$FA,$F7,$F4,$F1,$EF,$EC
;.byte $EA,$E8,$E6,$E4,$E3,$E2,$E1,$E1
;.byte $E0,$E1,$E1,$E2,$E3,$E4,$E6,$E8
;.byte $EA,$EC,$EF,$F1,$F4,$F7,$FA,$FD
gr_offsets_l:
.byte <$400,<$480,<$500,<$580,<$600,<$680,<$700,<$780
.byte <$428,<$4a8,<$528,<$5a8,<$628,<$6a8,<$728,<$7a8
.byte <$450,<$4d0,<$550,<$5d0,<$650,<$6d0,<$750,<$7d0
gr_offsets_h:
.byte >$400,>$480,>$500,>$580,>$600,>$680,>$700,>$780
.byte >$428,>$4a8,>$528,>$5a8,>$628,>$6a8,>$728,>$7a8
.byte >$450,>$4d0,>$550,>$5d0,>$650,>$6d0,>$750,>$7d0