dos33fsprogs/graphics/hgr/sprite/ball.s
2021-02-26 14:49:22 -05:00

248 lines
3.8 KiB
ArmAsm

; move a ball
; very slowly
; 133 bytes -- first attempt
; 130 bytes -- convert jmp to branches
; 132 bytes -- don't start at 0,0
; 128 bytes -- bit trick
; 126 bytes -- remove old code
; 145 bytes -- rounded edges
; 143 bytes -- optimize rounded edges
; 137 bytes -- move XX into X
; 136 bytes -- jmp back to loop
; 130 bytes -- paramaterize wall collision
; 125 bytes -- turn wall collision into loop
; 148 bytes -- add purple line
; 144 bytes -- move line to #$55 (same as purple)
; 142 bytes -- HCLR has Y at 0 at end
; 141 bytes -- hopefully useless CLC?
HGR_BITS = $1C
GBASL = $26
GBASH = $27
HGR_X = $E0
HGR_Y = $E2
HGR_COLOR = $E4
HGRPAGE = $E6
MX = $F7
MY = $F8
XDIR = $F9
YDIR = $FA
XC = $FB
YC = $FC
;XX = $FE
YY = $FF
PAGE0 = $C054
PAGE1 = $C055
HGR = $F3E2
HGR2 = $F3D8
HCLR = $F3F2
BKGND = $F3F6
HPOSN = $F411 ;; (Y,X) = X, A = Y
;; line addr in GBASL/GBASH
;; with offset in HGR.HORIZ, Y
HPLOT0 = $F457 ;; plot at (Y,X), (A)
HGLIN = $F53A ;; line to (A,X), (Y)
;===============================
;===============================
;===============================
;===============================
ball:
jsr HGR2 ; clear page1
; HGRPAGE now $40
; A is 0
; A is 0
sta MX
lda #$40
sta MY
; xdir and ydir start at 2?
ldy #$2
sty YDIR
sty XDIR
;=====================================
; loop
;=====================================
move_ball_loop:
;====================
; flip pages
; 16 bytes, can't seem to do better
;====================
bit HGRPAGE ; V set if $40 ; 2
bvc show_page1 ; 2
show_page2:
bit PAGE1 ; 3
lsr HGRPAGE ; 2
bne done_page ; 2
show_page1:
bit PAGE0 ; 3
asl HGRPAGE ; 2
done_page:
clear_screen:
;=======================
; clear screen to black
;=======================
jsr HCLR ; clear screen
; X untouched
; A and Y are 0?
;=======================
; draw purple line
;=======================
purple_line:
; draw purple line
; ldy #0
inx
; ldx #0 ; can we assume X is FF?
lda #$55 ; purple
sta HGR_COLOR
; lda #100 ; also line location
jsr HPLOT0 ;; (Y,X) = X, (A) = Y
lda #150
ldx #0
ldy #$55
jsr HGLIN ;; (A,X), (Y)
;===========================
; draw ball
;===========================
draw_ball:
lda MY ; actual Y
sta YY ; current Y
lda #13 ; 13 lines tall
sta YC ; count
ball_loop_y:
ldx MX ; load actual X
lda #14 ; 14 pixels wide
; check if rounded corders
ldy YC
cpy #13
beq make_round
cpy #1
bne write_xc
make_round:
inx ; start indented
inx
lda #10 ; and shorter
write_xc:
sta XC ; update xcount
ball_loop_x:
set_color:
txa ; XX more interesting than XC?
eor YC
and #$4
beq set_orange
set_white:
lda #$FF ; white2
.byte $2C ; bit trick
set_orange:
lda #$AA ; orange
set_hgr_color:
sta HGR_COLOR
hplot_time:
; hplot
ldy #0
; ; XX already in X
lda YY ; put YY into A
jsr HPLOT0 ;; (Y,X) = X, A = Y
;; destroys X, Y, A
;; but, X is in HGR.X and Y is in HGR.X+1
;; AA is in HGR.Y
ldx HGR_X ; restore XX into X
inx ; inc XX
dec XC
bne ball_loop_x
inc YY
dec YC
bne ball_loop_y
;===========================
; move sprite
;===========================
ldx #1
handle_wall_loop:
;=================================
; handle wall
;=================================
handle_wall:
lda MX,X ; load X location
; clc
adc XDIR,X ; add in our direction/speed
bmi switch_xdir ; if <0 or > 127 then switch direction
sta MX,X
bpl noswitch_xdir ; otherwise store and skip
switch_xdir:
lda XDIR,X ; get direction and inverse
eor #$FF
sta XDIR,X
inc XDIR,X ; two's complement
noswitch_xdir:
dex
bpl handle_wall_loop
bmi move_ball_loop
;==============
; so we can call from basic
jmp ball