dos33fsprogs/demos/second/roto.s
2023-08-15 16:02:53 -04:00

188 lines
2.5 KiB
ArmAsm

; do a (hopefully fast) roto-zoom
do_rotozoom:
;================================
; Clear screen and setup graphics
;================================
bit PAGE0 ; set page 0
bit LORES ; Lo-res graphics
lda #0
sta DISP_PAGE
lda #4
sta DRAW_PAGE
;===================================
; Clear top/bottom of page 0 and 1
;===================================
jsr clear_screens
;===================================
; init the multiply tables
;===================================
jsr init_multiply_tables
;======================
; show the title screen
;======================
; Title Screen
title_screen:
load_background:
;===========================
; Clear both bottoms
; jsr clear_bottoms
;=============================
; Load title
lda #<lens_zx02
sta zx_src_l+1
lda #>lens_zx02
sta zx_src_h+1
lda #$40
jsr zx02_full_decomp
;=================================
; copy to both pages
jsr gr_copy_to_current
jsr page_flip
jsr gr_copy_to_current
jsr wait_until_keypress
;=================================
; main loop
lda #0
sta ANGLE
sta SCALE_F
sta FRAMEL
lda #1
sta SCALE_I
main_loop:
jsr rotozoom
jsr page_flip
lda KEYPRESS ; 4
bpl no_keypress
bit KEYRESET ; clear the keyboard buffer
rts
no_keypress:
clc
lda FRAMEL
adc direction
sta FRAMEL
cmp #$f8
beq back_at_zero
cmp #33
beq at_far_end
bne done_reverse
back_at_zero:
at_far_end:
; change bg color
lda roto_color_even_smc+1
clc
adc #$01
and #$0f
sta roto_color_even_smc+1
lda roto_color_odd_smc+1
clc
adc #$10
and #$f0
sta roto_color_odd_smc+1
; reverse direction
lda direction
eor #$ff
clc
adc #1
sta direction
lda scaleaddl
eor #$ff
clc
adc #1
sta scaleaddl
lda scaleaddh
eor #$ff
adc #0
sta scaleaddh
done_reverse:
clc
lda ANGLE
adc direction
and #$1f
sta ANGLE
clc
lda SCALE_F
adc scaleaddl
sta SCALE_F
lda SCALE_I
adc scaleaddh
sta SCALE_I
jmp main_loop
direction: .byte $01
scaleaddl: .byte $10
scaleaddh: .byte $00
;===============================================
; External modules
;===============================================
.include "rotozoom.s"
.include "gr_pageflip.s"
;.include "gr_fast_clear.s"
.include "gr_copy.s"
.include "gr_offsets.s"
.include "c00_scrn_offsets.s"
.include "multiply_fast.s"
;===============================================
; Data
;===============================================
lens_zx02:
.incbin "graphics/lenspic.gr.zx02"