dos33fsprogs/graphics/gr/plasma/plasma.s
2021-01-09 12:26:57 -05:00

131 lines
1.6 KiB
ArmAsm

; do a (hopefully fast) plasma
; 151 -- original
; 137 -- optimize generation
; 136 -- align lookup table so we can index it easier
; 130 -- optimize indexing of lookup
; 126 -- run loops backaward
; 124 -- notice X already 0 before plot
.include "zp.inc"
.include "hardware.inc"
CTEMP = $FC
SAVEOFF = $FD
SAVEX = $FE
SAVEY = $FF
;================================
; Clear screen and setup graphics
;================================
jsr SETGR
lda #0
sta DISP_PAGE
lda #4
sta DRAW_PAGE
;col = ( 8.0 + (sintable[xx&0xf])
; + 8.0 + (sintable[yy&0xf])
; ) / 2;
create_lookup:
ldy #15
create_yloop:
ldx #15
create_xloop:
clc
lda #15
adc sinetable,X
adc sinetable,Y
lsr
lookup_smc:
sta lookup ; always starts at $d00
inc lookup_smc+1
dex
bpl create_xloop
dey
bpl create_yloop
create_lookup_done:
forever_loop:
cycle_colors:
; cycle colors
ldx #0
cycle_loop:
inc lookup,X
inx
bne cycle_loop
plot_frame:
; plot frame
;ldx #0 ; YY=0
plot_yloop:
ldy #0 ; XX = 0
plot_xloop:
stx SAVEX ; SAVE YY
sty SAVEY ; SAVE XX
tya
and #$f
sta CTEMP
txa
and #$f
asl
asl
asl
asl
ora CTEMP
tax
lda lookup,X
and #$f
lsr
tax
lda colorlookup,X
jsr SETCOL
lda SAVEX
jsr PLOT ; plot at Y,A
ldy SAVEY ; restore XX
ldx SAVEX ; restore YY
iny
cpy #40
bne plot_xloop
inx
cpx #40
bne plot_yloop
beq forever_loop
sinetable:
.byte $00,$03,$05,$07,$08,$07,$05,$03
.byte $00,$FD,$FB,$F9,$F8,$F9,$FB,$FD
colorlookup:
;.byte $00,$00,$05,$05,$07,$07,$0f,$0f
;.byte $07,$07,$06,$06,$02,$02,$05,$05
.byte $00,$05,$07,$0f,$07,$06,$02,$05
.org $d00
;.align $100
lookup: