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Realtime stars with perspective table for Atari computer
;*******************************************
;* Realtime stars with perspective table *
;* By Jesper Rudberg *
;* (Kasper of Electra) *
;* This is one of my first versons but it *
;* shows the tech you use. *
;* Hope you learn something new anyway *
;* The code is very bad comented and you *
;* have to fix the screen address if you *
;* have a 520. *
;* Should be assembled from Devpac 2.23 *
;* el dyl. *
;*******************************************
nr_pnts equ 330 antal punkter
helan equ 256
halvan equ helan/2
y_scr equ 40*200
x_scr equ 40*320
move.w #0,-(sp)
move.l #$f8000,-(sp)
move.l #$f0000,-(sp)
move.w #5,-(sp)
trap #14
add.l #12,sp
clr.l -(sp)
move.w #$20,-(sp)
trap #1
addq.l #6,sp
move.w #$111,$ff8242
move.w #$222,$ff8244
move.w #$333,$ff8246
move.w #$444,$ff8248
move.w #$555,$ff824a
move.w #$666,$ff824c
move.w #$777,$ff824e
move.w #$0,$ff8250
jsr studs
jsr drw_clc
jsr random
jsr screenchg
vbl move.w #37,-(sp) wait for vbl
trap #14
addq.l #2,sp
move.w #$000,$ff8240
jsr screenchg byt screen mm
;**********************************************
move.w #0,d0 clear points
move.w #0,d1
move.w #0,d2
move.l screen,a0
move.l nowthis,a1
jsr (a1)
;***********************************************
jsr hot_stf rita ut
rept 25
move.w #$111,$ff8240
endr
move.w #$000,$ff8240
cmp.b #185,$fffc02
bne vbl
move.w #$777,$ff8240
move.w #$000,$ff8246
clr.w -(sp)
trap #1
;***************************************************************
hot_stf
;*************************
;* Check my var *
;*************************
nono lea runt_kurv,a6
add.w add3,a6
add.w #6,add3
cmp.w #-10000,(a6)
bne dont_care
move.w #0,add3
bra nono
dont_care move.w (a6),my_x
move.w 2(a6),my_y
move.w 4(a6),my_z
cmp.w #-halvan,my_x
bge got1
add.w #helan,my_x
got1 cmp.w #halvan,my_x
ble got2
sub.w #helan,my_x
got2 cmp.w #-halvan,my_y
bge got3
add.w #helan,my_y
got3 cmp.w #halvan,my_y
ble got4
sub.w #helan,my_y
got4
cmp.w #0,my_z
bge got5
add.w #helan,my_z
got5 cmp.w #helan,my_z
ble got6
sub.w #helan,my_z
got6
move.w my_x,d1
move.w my_y,d2
move.w my_z,d3
;*************************************************************************
;* Valj ut lampliga stjarnor *
;* fixa cords *
;******************************
lea ur_cords,a0 pekar pa massa cords
lea sorted,a2
move.l #nr_pnts-1,d0
lappa move.w (a0)+,d4 x
add.b d1,d4
move.w (a0)+,d5 y
add.b d2,d5
move.w (a0)+,d6 z
add.b d3,d6
;**********************************************************************
;** Hamta perspectiv **
;************************
lsl.w #1,d4
lsl.w #1,d5
move.w d6,(a2)+
move.l #9,d7
lsl.l d7,d6
lea pre_z,a3 hamta tabell
add.l d6,a3
lea (a3),a4
add.w d5,a3 y
move.w (a3),(a2)+
add.w d4,a4 x
move.w (a4),(a2)+
dbf d0,lappa
;**************************************************
;* draw point *
;************************************************************************
draw_pnts move.l screen,a6
move.l #$48a80007,d3 =(movem.w d0-2,xx(a0))
move.l #$31400000,d0 =(move.w d0,xx(a0))
move.w #y_scr/2+100,d6 y_varde
move.w #x_scr/2+160,d4 x_varde
move.l #nr_pnts-1,d2
lea sorted,a4 pekar pa x,y varden
move.l nowthis,a5 pekar pa savs tabell
rita move.w (a4)+,d7 get z
lea y_preps,a1
move.w (a4)+,d0 get y varde to d0
add.w d6,d0 mitt
lsl.w #1,d0
add.w d0,a1 y till y
move.w (a1)+,d0
lea x_preps,a2
move.w (a4)+,d1 get x varde to d1
add.w d4,d1
lsl.w #2,d1
add.w d1,a2 x till x
move.l (a2)+,d1
add.w d1,d0 d0=adress offset
swap d1 d1.w=ratt bit
lsr.w #3,d7
and.w #$fc,d7
lea jumps(pc),a0
add.w d7,a0
move.l (a0),a0
jm jmp (a0)
farg7 move.l d3,(a5)+
move.w d0,(a5)+
or.w d1,(a6,d0.w)
or.w d1,2(a6,d0.w)
or.w d1,4(a6,d0.w)
dbf d2,rita
move.w #$4e75,(a5)
rts
farg1 move.l d0,(a5)+
or.w d1,(a6,d0.w)
dbf d2,rita
move.w #$4e75,(a5)
rts
farg2 move.l d3,(a5)+
move.w d0,(a5)+
or.w d1,2(a6,d0.w)
dbf d2,rita
move.w #$4e75,(a5)
rts
farg3 move.l d3,(a5)+
move.w d0,(a5)+
or.w d1,(a6,d0.w)
or.w d1,2(a6,d0.w)
dbf d2,rita
move.w #$4e75,(a5)
rts
farg4 move.l d3,(a5)+
move.w d0,(a5)+
or.w d1,4(a6,d0.w)
dbf d2,rita
move.w #$4e75,(a5)
rts
farg5 move.l d3,(a5)+
move.w d0,(a5)+
or.w d1,(a6,d0.w)
or.w d1,4(a6,d0.w)
dbf d2,rita
move.w #$4e75,(a5)
rts
farg6 move.l d3,(a5)+
move.w d0,(a5)+
or.w d1,2(a6,d0.w)
or.w d1,4(a6,d0.w)
dbf d2,rita
move.w #$4e75,(a5)
rts
jumps dc.l farg7,farg7,farg6,farg5,farg4,farg3,farg2,farg1,jm+2
;*****************************************************************
;** Draw point: calc routs **
;******************************
drw_clc lea y_preps(pc),a0
add.l #y_scr,a0
move.l #0,d1
move.l #200-1,d0 200 rader
dr_clc_lpy move.l d1,d2 spara d1
mulu #160,d2 160 bytes per rad
move.w d2,(a0)+ spara till y_preprtabellen
addq.l #1,d1 nasta rad
dbf d0,dr_clc_lpy
;********************************************************************************
lea x_preps,a0
add.l #x_scr*2,a0
move.l #0,d1
move.l #320-1,d0 320 pixels per rad
dr_clc_lpx move.l d1,d2 spara d1
divu #16,d2
move.l d2,d3 spara d2
lsl.w #3,d3 *8(ratt byte/word)
swap d2
move.w #15,d4
sub.w d2,d4 15-d2(ratt bit (omvant))
move.w #1,d2
lsl.w d4,d2 ratt or varde
swap d2 or vardet overst
move.w d3,d2 byte vardet underst
move.l d2,(a0)+ spara i x_prepstabellen
addq.l #1,d1
dbf d0,dr_clc_lpx
rts
;*********************************************
screenchg cmp.l #$f8000,screen
beq chg_it
move.l #savs,nowthis
move.l #$f8000,screen
move.b #$0f,$ffff8201
move.b #$80,$ffff8203
rts
chg_it move.l #savs2,nowthis
move.l #$f0000,screen
move.b #$0f,$ff8201
move.b #$00,$ff8203
rts
;*****************************************************
;* Slump kordinater *
;********************
random lea ur_cords,a6
move.l #nr_pnts*3,d6
looopy move.w #$11,-(sp)
trap #14
addq.l #2,sp
and.w #helan-1,d0
move.w d0,(a6)+
dbf d6,looopy
;************************************************
;* Fixa perspectiv preps *
;*************************
lea pre_z,a0
move.l #helan-1,d1
z_1_lp move.l #helan-1,d0
move.l #0,d2
x_1_lp move.l d1,d6 get z-varde
move.l d2,d4 get x,y varde
sub.w #halvan,d4
lsl.w #2,d4 lagom factor(storlek)
move.w d4,d7 spara for add
neg.w d6 omvand for ratt bitpl
add.w #helan,d6
muls d6,d4
add.w #34,d6 avstand fran screen
neg d6
divs.w d6,d4
add.w d7,d4
move.w d4,(a0)+ spara
addq.l #1,d2 oka x,y varde
dbf d0,x_1_lp
dbf d1,z_1_lp
rts
;**************************************************************************
;*** Fixar dvs kurvor,z_adder,mm ***
;**************************************************************************
studs lea runt_kurv,a1 kurvor mm i a1
lea varden,a4
move.l #2-1,d7
lopy lea sin_tab,a0 sin kurva i a0
move.l #0,d3 noll fran borjan
move.l #360-1,d0 360 grader=1 varv
moveq.l #14,d2 lsr data (=divu 2^14)
;*************************************************************************
;* X varden *
;************
kurv_lp move.w (a0)+,d1 hamta sin varde
muls (a4),d1 (* 100)
lsr.l d2,d1 (/16384)
mer_test3 cmp.w #helan,d1
ble klar4
sub.w #helan,d1
bra mer_test3
klar4 cmp.w #-helan,d1
bge klar5
add.l #helan,d1
bra klar4
klar5
move.w d1,(a1)+ spara undan X-varde
;*************************************************************************
;* Y-varden *
;************
move.w 178(a0),d4 hamta cos (sin+2+88)
muls 2(a4),d4 (* 300)
lsr.l d2,d4 dela lite
mer_test2 cmp.w #helan,d4
ble klar2
sub.w #helan,d4
bra mer_test2
klar2 cmp.w #-helan,d4
bge klar3
add.l #helan,d4
bra klar2
klar3
move.w d4,(a1)+ spara undan z_adder
;*************************************************************************
;* Z-varden *
;************
lea sin_tab,a2 sin kurva i a2
add.w 4(a4),d3 oka adder
add.l d3,a2 fram i kurvan
cmp.w #360*2,d3 testa slut
blt so_what inte so what
move.l #0,d3 annars nolla adder
so_what move.w (a2),d1 hamta studs-sin varde
muls 6(a4),d1
lsr.l d2,d1
add.w 6(a4),d1
mer_test cmp.w #helan,d1
ble klar
sub.w #helan,d1
bra mer_test
klar move.w d1,(a1)+ spara undan y-varde
dbf d0,kurv_lp igen?
add.w #8,a4
dbf d7,lopy
move.w #-10000,(a1)
move.w #-10000,(a1)
move.w #-10000,(a1)
rts
varden dc.w helan,helan,4,helan
dc.w helan,helan,4,helan
;***********************************************
screen dc.l $f8000
nowthis ds.l 1
add3 dc.l 0
my_x dc.w 0
my_y dc.w 0
my_z dc.w 0
sin_tab dc.w 0,286,572,857,1143,1428,1713,1997,2280
dc.w 2563,2845,3126,3406,3686,3964,4240,4516
dc.w 4790,5063,5334,5604,5872,6138,6402,6664
dc.w 6924,7182,7438,7692,7943,8192,8438,8682
dc.w 8923,9162,9397,9630,9860,10087,10311,10531
dc.w 10749,10963,11174,11381,11585,11786,11982,12176
dc.w 12365,12551,12733,12911,13085,13255,13421,13583
dc.w 13741,13894,14044,14189,14330,14466,14598,14726
dc.w 14849,14962,15082,15191,15296,15396,15491,15582
dc.w 15668,15749,15826,15897,15964,16026,16083,16135
dc.w 16182,16225,16262,16294,16322,16344,16362,16374
dc.w 16382
costab dc.w 16384
dc.w 16382,16374,16362,16344,16322,16294,16262,16225
dc.w 16182
dc.w 16135,16083,16026,15964,15897,15826,15749,15668
dc.w 15582,15449,15396,15296,15191,15082,14962,14849
dc.w 14726,14598,14466,14330,14189,14044,13894,13741
dc.w 13583,13421,13255,13085,12911,12733,12551,12365
dc.w 12176,11982,11786,11585,11381,11174,10963,10749
dc.w 10531,10311,10087,9860,9630,9397,9162,8923
dc.w 8682,8438,8192,7943,7692,7438,7182,6924
dc.w 6664,6402,6138,5872,5604,5334,5063,4790
dc.w 4516,4240,3964,3686,3406,3126,2845,2563
dc.w 2280,1997,1713,1428,1143,857,572,286,0
dc.w -286,-572,-857,-1143,-1428,-1713,-1997,-2280
dc.w -2563,-2845,-3126,-3406,-3686,-3964,-4240,-4516
dc.w -4790,-5063,-5334,-5604,-5872,-6138,-6402,-6664
dc.w -6924,-7182,-7438,-7692,-7943,-8192,-8438,-8682
dc.w -8923,-9162,-9397,-9630,-9860,-10087,-10311,-10531
dc.w -10749,-10963,-11174,-11381,-11585,-11786,-11982,-12176
dc.w -12365,-12551,-12733,-12911,-13085,-13255,-13421,-13583
dc.w -13741,-13894,-14044,-14189,-14330,-14466,-14598,-14726
dc.w -14849,-14962,-15082,-15191,-15296,-15396,-15491,-15582
dc.w -15668,-15749,-15826,-15897,-15964,-16026,-16083,-16135
dc.w -16182,-16225,-16262,-16294,-16322,-16344,-16362,-16374
dc.w -16382,-16384
dc.w -16382,-16374,-16362,-16344,-16322,-16294,-16262,-16225
dc.w -16182
dc.w -16135,-16083,-16026,-15964,-15897,-15826,-15749,-15668
dc.w -15582,-15449,-15396,-15296,-15191,-15082,-14962,-14849
dc.w -14726,-14598,-14466,-14330,-14189,-14044,-13894,-13741
dc.w -13583,-13421,-13255,-13085,-12911,-12733,-12551,-12365
dc.w -12176,-11982,-11786,-11585,-11381,-11174,-10963,-10749
dc.w -10531,-10311,-10087,-9860,-9630,-9397,-9162,-8923
dc.w -8682,-8438,-8192,-7943,-7692,-7438,-7182,-6924
dc.w -6664,-6402,-6138,-5872,-5604,-5334,-5063,-4790
dc.w -4516,-4240,-3964,-3686,-3406,-3126,-2845,-2563
dc.w -2280,-1997,-1713,-1428,-1143,-857,-572,-286,0
dc.w 286,572,857,1143,1428,1713,1997,2280
dc.w 2563,2845,3126,3406,3686,3964,4240,4516
dc.w 4790,5063,5334,5604,5872,6138,6402,6664
dc.w 6924,7182,7438,7692,7943,8192,8438,8682
dc.w 8923,9162,9397,9630,9860,10087,10311,10531
dc.w 10749,10963,11174,11381,11585,11786,11982,12176
dc.w 12365,12551,12733,12911,13085,13255,13421,13583
dc.w 13741,13894,14044,14189,14330,14466,14598,14726
dc.w 14849,14962,15082,15191,15296,15396,15491,15582
dc.w 15668,15749,15826,15897,15964,16026,16083,16135
dc.w 16182,16225,16262,16294,16322,16344,16362,16374
dc.w 16382,16384,16382
y_preps dcb.w y_scr,200*160
savs dcb.w nr_pnts*4,$4e75
savs2 dcb.w nr_pnts*4,$4e75
section bss
x_preps ds.l x_scr
sorted ds.w nr_pnts*3
ur_cords ds.l 3*nr_pnts
runt_kurv ds.l 600*10
pre_z ds.w helan*helan
