dos33fsprogs/graphics/hgr/tiny_triangles/sier_moveright.s
2021-04-12 14:47:49 -04:00

229 lines
3.2 KiB
ArmAsm

; sierpinski-like demo
; based on the code from Hellmood's Memories demo
; by Vince `deater` Weaver <vince@deater.net>
; the simple sierpinski you more or less just plot
; X AND Y
; Hellmood's you plot something more or less like
; COLOR = ( (Y-(X*T)) & (X+(Y*T) ) & 0xf0
; where T is an incrementing frame value
; to get speed on 6502/Apple II we change the multiplies to
; a series of 16-bit 8.8 fixed point adds
; TODO:
; HPLOT timing
; MOVERIGHT timing
; MOVERIGHT MOVEDOWN timing
; LOOKUP TABLE timing
; zero page
HGR_BITS = $1C
GBASH = $27
MASK = $2E
COLOR = $30
HGR_X = $E0
HGR_Y = $E2
HGR_COLOR = $E4
SAVEX = $F7
XX_TH = $F8
XX_TL = $F9
YY = $FA
YY_TH = $FB
YY_TL = $FC
;T_L = $FD
;T_H = $FE
SAVED = $FF
; Soft switches
FULLGR = $C052
PAGE1 = $C054
PAGE2 = $C055
LORES = $C056 ; Enable LORES graphics
; ROM routines
HGR = $F3E2
HGR2 = $F3D8
HPOSN = $F411
HPLOT0 = $F457
HPLOT1 = $F45A ; skip the HPOSN call
COLOR_SHIFT = $F47E ; shift color for odd/even Y (0..7 or 7..13)
MOVE_RIGHT = $F48A ; move next plot location one to the right
COLORTBL = $F6F6
;.zeropage
;.globalzp T_L,T_H
;================================
; Clear screen and setup graphics
;================================
sier:
jsr HGR2 ; set FULLGR, sets A=0
; lda #0 ; start with multiplier 0
; sta T_L
; sta T_H
sier_outer:
ldy #0 ; YY starts at 0
sty YY
sty YY_TL
sty YY_TH
sier_yloop:
; calc YY_T (8.8 fixed point add)
; save space by skipping clc as it's only a slight variation w/o
; clc
lda YY_TL
adc T_L
sta YY_TL
lda YY_TH
adc T_H
sta YY_TH
; XX in X
; YY in YY
ldy #0
ldx #0 ; XX = 0
lda YY ; Y co-ord
jsr HPOSN ; set cursor position to (Y,X), (A)
; ldy HGR_Y
; lda GBASH
;draw_page_smc:
; adc #0
; sta GBASH ; adjust for PAGE1/PAGE2 ($400/$800)
; plp
; jsr $f806 ; trick to calculate MASK by jumping
; into middle of PLOT routine
; reset XX to 0
ldx #0 ; XX
stx XX_TL
stx XX_TH
sier_xloop:
stx SAVEX
; want (YY-(XX*T)) & (XX+(YY*T)
; SAVED = XX+(Y*T)
; clc
txa ; XX
adc YY_TH
sta SAVED
; calc XX*T
; clc
lda XX_TL
adc T_L
sta XX_TL
lda XX_TH
adc T_H
sta XX_TH
; calc (YY-X_T)
lda YY
sec
sbc XX_TH
; want (YY-(XX*T)) & (XX+(YY*T)
and SAVED
and #$f0
beq white
black:
lda #0 ; black
.byte $2C ; bit trick
white:
lda #$ff ; white
color_ready:
; tax
; tya
; lsr ; check even or odd
; php
; lda COLORTBL,X
sta HGR_BITS
; plp
; bcc no_shift
; jsr COLOR_SHIFT ; if odd then color shift
no_shift:
jsr HPLOT1 ; plot at current position
jsr MOVE_RIGHT ; move current position right (trashes A)
ldx SAVEX ; restore X
;==================================
inx ; XX
bne sier_xloop
;==================================
inc YY ; repeat until Y=192
ldy YY
cpy #192
bne sier_yloop
; inc T
; clc
lda T_L
blah_smc:
adc #1
sta T_L
bcc no_carry
inc T_H
no_carry:
; speed up the zoom as it goes
inc blah_smc+1
; x is 48
;flip_pages:
; lda draw_page_smc+1 ; DRAW_PAGE
; beq done_page
; inx
;done_page:
; X=48 ($30) PAGE1=$C054-$30=$C024
; ldy $C024,X ; set display page to PAGE1 or PAGE2
; eor #$4 ; flip draw page between $400/$800
; sta draw_page_smc+1 ; DRAW_PAGE
jmp sier_outer ; what can we branch on?
T_L: .byte $00
T_H: .byte $00