********************* *********************** ****** . . ****** **** . . . Init & Exit code . " **** *** ' . """""""""""""""" . *** ** . . . . . " . . ** ** " written in a hurry for . . ** *** . : . . """""""""""""""""""""" . *** **** #Amycoders' starfield compo by **** ****** . """"""""""""""""""""""""""" morbid ********************* *********************** bsr CloseWB ; Flush view and disable multitasking bsr OpenScreen ; Set pointers and sync jsr Starfield_init ;Init starfield ** ************************************************************ ************************************************************ ** ** >>> M A I N <<< ** Main btst #6,$bfe001 beq Exit ************************************************************ bsr DisplayScreen jsr Starfield ;call starfield (a0=Bitplane) bra Main ** ************************************************************ ** ** Flush view & disable system ** CloseWB movea.l 4.w,a6 ; exec base jsr -132(a6) ; Forbid jsr -120(a6) ; Disable lea GfxName(pc),a1 ; graphics.library moveq #0,d0 ; whatever verision jsr -552(a6) ; open it ! move.l d0,GfxBase ; store gfxbase movea.l d0,a6 ; gfxbase in a6 move.l $22(a6),OldView ; store system view move.l $26(a6),OldCop ; store system copper sub.l a1,a1 jsr -222(a6) ; flush view (LoadView) jsr -270(a6) ; WaitTOF jsr -270(a6) ; twice for interlaced views move.w $dff002,OldDMAcon ; store old dma control register ori.w #$8000,OldDMAcon ; set bit #15 move.w #$7fff,$dff096 move.w #$8380,$dff096 rts GfxName dc.b 'graphics.library',0 even GfxBase dc.l 0 OldView dc.l 0 OldCop dc.l 0 OldDMAcon dc.w 0 cnop 0,4 ** ************************************************************* ** ** Display Screen ** DisplayScreen movem.l d0-d1,-(sp) move.b $bfe801,d0 .wait cmp.b $bfe801,d0 beq.b .wait move.l screen_logical(pc),d0 move.l screen_physical(pc),screen_logical move.l d0,screen_physical lea copper_bpl,a0 move.w d0,6(a0) ; lower part of bpl address swap d0 move.w d0,2(a0) ; higher word movea.l screen_logical(pc),a0 moveq #0,d0 move.l #(320/32)*256-1,d1 .clear move.l d0,(a0)+ ; clear logical screen dbf d1,.clear lea -(320/8)*256(a0),a0 movem.l (sp)+,d0-d1 rts screen_physical dc.l 0 screen_logical dc.l 0 ** ************************************************************* ** ** Open Screen ** OpenScreen lea $dff000,a5 move.l #Copper,$80(a5) move.w #$2c81,$08e(a5) ; display window start pos move.w #$2cc1,$090(a5) ; display window stop pos move.w #$0038,$092(a5) ; data fetch start pos move.w #$00d0,$094(a5) ; data fetch stop pos move.l #ScreenA,screen_logical move.l #ScreenB,screen_physical bsr DisplayScreen rts ** ************************************************************** ** ** Open WB ** Exit lea $dff000,a5 move.w #$7fff,$96(a5) ; clear dmacon move.w OldDMAcon(pc),$96(a5) ; set old bits move.l GfxBase(pc),a6 ; gfxbase in a6 move.l OldCop(pc),$80(a5) ; restart old copperlist move.l OldView(pc),a1 jsr -222(a6) ; Load system view move.l a6,a1 move.l 4.w,a6 jsr -414(a6) ; close graphics.library jsr -126(a6) ; Enable jsr -138(a6) ; Permit rts ************************************************************************ section screens,bss_c ScreenA ds.b (320*256)/8 ScreenB ds.b (320*256)/8 ************************************************************************ section copperlist,data_c Copper dc.l $01001000 ; bplcon0 dc.l $01080000 ; bpl1mod dc.l $010a0000 ; bpl2mod dc.l $01800000 ; colour 0 = black dc.l $01820fff ; colour 1 = white copper_bpl dc.l $00e00000 ; bpl1pth dc.l $00e20000 ; bpl1ptl dc.l $fffffffe ************************************************************************** ************************************************************************** ** ** ** Your starfield code starts here ** ** ************************************************************************** ************************************************************************** section code,code ;put your code here ********************************************* ** Do all initialisations here ********************************************* Starfield_init: a ; who said this has to be used? ;) b rts ********************************************* ** This routine is called once a frame ** ** The destination Bitplane is given in a0 ********************************************* * 86 bytes solution by gREY%CRUX^BABE -%- grey@space.ch * join the inactivity fan-club - 3rd birthday soon reached! ;) * i'm simply too bored to optimize any further... SPEED = 6 * 0 =< SPEED =< 8 Starfield: c lea StarTab,a1 move.w #512-1,d7 * 512 stars calculated .star: move.w #255,d5 * init some neccessary moveq #-128,d6 * constants movem.w (a1)+,d0-d2 * load x,y,z subq.b #SPEED,d2 * move towards viewer bgt.s .noNEW * if not past eyepoint add.w d7,d2 * calculate new x,y,z sub.w d2,d1 * this RND() is real mulu d7,d1 * crap, but who wants sub.w d1,d0 * something nice in mulu d7,d0 * such a compo? :) and.w d5,d2 * make sure that all and.w d5,d0 * coords are within and.w d5,d1 * screen area add.w d6,d1 * center y in 3D add.w d6,d0 * center x in 3D .noNEW: movem.w d0-d2,-6(a1) * save x,y,z muls d5,d0 * x * 255 muls d5,d1 * y * 255 add.w d5,d2 * z + 255 divs d2,d1 * y / z sub.w #52,d2 * distort projection divs d2,d0 * x / z add.w #160,d0 * center x-coord sub.w d6,d1 * center y-coord mulu #40,d1 * modulo y-coord ext.l d0 * neccessary!! bfset (a0,d1.l){d0:1} * set star dbra d7,.star * repeat until done d rts printt "Length of code:" printv ((b-a)+(d-c)) section bss,bss ;put your tables heres StarTab: ds.w 3*512 .