Scene World 22

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;-------------------------------------- ;Scene World #22 ; ;C64 6502 Assembly Game Programming ;tutorial ;-------------------------------------- ;PLANET POPPER V2 ;================ ;Programming, Planet Sprites, ;Charset and Music by Richard Bayliss ;Bitmap screen and game sprites by ;Johan Janssen. ;-------------------------------------- ;Last time in the assembly programming ;tutorial. We started making a simple ;shoot 'em up game. Now we are going ;to tweak it to make it look better. ;In this part of the tutorial, we are ;going to turn it into an actual game. ;Also slightly different to the ;previous chapter. ;The new version of the game will ;allow you to display a picture, a new ;charset, new sprites and also play ;music. We have started from scratch ;to make way for some new features in ;the game. Enjoy playing around with ;this source. ;We also have a simple front end for ;the game as well. ;-------------------------------------- ;First of all, some variables in which ;represent various features for the ;game. raspos1 = $00;Raster position before ;calling an interrupt ;frame. raspos2 = $2e;Raster position for irq1 ; ;Displays game background ;and game sprites raspos3 = $f1;Raster position for irq2 ; ;Displays status bar for ;score. Also hides ;visible sprites. raspos4 = $fa;Raster position for ;syncronizing timers and ;playing music. delaytime = $0801 ;Sync timer ;Object pointers in which are used as a ;ghost sprite. This needs to be used to ;store to an actual hardware sprite ;pointer. scoreval = $07c7 ;First digit for score shieldval = $07e5;First Digit for the ;Player's shield. objpos = $0810 ;Temporary software ;sprite pointers. For ;positioning sprites. animpointer = $0820 ;Counter for main ;sprite animation animdelay = $0821 ;Delay pointer for ;sprite animation. planetstore1 = $0822;Planet animation planetstore2 = $0823;storage pointers. planetstore3 = $0824;Where a frame is planetstore4 = $0825;read from the planetstore5 = $0826;frame table and planetstore6 = $0827;then stored to the playerstore = $0828 ;planets. Or Player explodedelay = $0829 ;Timing and count explodeptr = $082a ;for the explosion explodestore = $082b ;animation collstore = $0830 ;Software Sprite ;to sprite ;collision planet1hit = $0840 ;Pointers to check planet2hit = $0841 ;to see whether or planet3hit = $0842 ;not the planets planet4hit = $0852 ;have been shot by planet5hit = $0862 ;the player. planet6hit = $0872 ; planet1speed = $0873 ;Generated speed planet2speed = $0874 ;pointers in which planet3speed = $0875 ;are stored to the planet4speed = $0876 ;planet's movement planet5speed = $0877 ;routine. planet6speed = $0878 ; planetdir = $0879 ;Direction pointer planettime = $087a ;Duration and dirpointer = $087b ;direction for ;moving planets colourstore = $0880 ;Sprite colour ;pointers for ;raster IRQ. randcounter = $0890 ;Pointer to call ;a random position randpos = $0891 ;Random position randspeed = $0892 ;Random speed firebutton = $0893 ;Joystick fire ;pressed and ;released. xpos = $0894 ;Title soft scroll ;pointer titlescreentext = $3800;Where the title ;screen text has ;been stored. scrolltext = $3c00 ;Same for the ;scrolling msg. titlelast = $06c0 ;First digit for ;last score titlebest = $06c0+40 ;First digit for ;high score. ;Music ... ; ;Most music editors/composers in the ;C64 demo scene plays tunes using: ; ;LDA #$00 ;JSR $1000 ;init music ; ;JSR $1003 ; ;DMC, JCH, GoatTracker, Voicetracker, ;SidWizard, etc use this. ; songno = $00 ;Song number musicinit = $1000 ;Initialise music musicplay = $1003 ;Play music ;Start code. Using crunchers / packers ;set $2800 as JMP address. Antwere else ;will not really help much :) #$37 as ;$01 can be set. *= $2800 ;Initialize Richard's music, as ;this will be used only once for both ;front end and game. lda #songno jsr musicinit titlescreen sei ;Set IRQ interrupt lda #$00 ;Black border sta $d020 ;and screen. sta $d021 ;Setup the title screen text display ldx #$00 ; puttitle lda $3800,x ;Copy whole text sta $0400,x ;memory from lda $3900,x ;$3800-$3be7 and sta $0500,x ;put it in the lda $3a00,x ;default screen sta $0600,x ;position in VIC lda $3ae8,x ;Bank #$03. sta $06e8,x lda #$0c ;Grey text sta $d800,x sta $d900,x sta $da00,x sta $dae8,x inx bne puttitle ;Ensure all sprites are switched off. lda #$00 sta $d015 sta $d01b sta $d01d sta $d017 ;Setup up VIC Bank #$03, and other ;hardware pointers for front end. lda #$03 ;VIC Bank #$03 sta $dd00 lda #$08 ;Multicolour OFF sta $d016 lda #$18 ;Charset at $2000 sta $d018 lda #$00 ;Initialize the sta firebutton ;fire button + sta xpos ;soft scroll lda #<scrolltext ;And of sta messread+1 ;course reset lda #>scrolltext ;the scroll sta messread+2 ;message. ;Copy the final score and high score to ;where final and top scores are set. ldx #$00 copyscores lda finalscore,x sta titlelast,x lda topscore,x sta titlebest,x inx cpx #6 bne copyscores ;Setup title screen interrupts. lda #<tirq1 ;Low bit of irq sta $0314 ;Store to vector lda #>tirq1 ;Hi bit of irq sta $0315 ;Store to vector lda #raspos1;Default raster sta $d012 ;position lda #$7f ;CIA set to sta $dc0d ;Interrupt lda #$1b ; sta $d011 ;Screen on lda #$01 ;IRQ sync set sta $d01a ror $d019 cli ;Clear IRQ flag ;The main loop of the title screen. titleloop lda #0 ;Synchronize the sta delaytime ;timer. cmp delaytime beq *-3 jsr scrollmess ;Call scroller lda $dc00 ;Wait for fire lsr a ;on joystick lsr a ;in port 2 lsr a lsr a lsr a bit firebutton ror firebutton bmi titleloop bvc titleloop jmp gamestart ;Run game. ;The main scroll text routine. scrollmess lda xpos ;Control the sec ;speed and the sbc #1 ;smoothness of the and #$07 ;scroll. sta xpos bcs endscr ldx #$00 ;Pull all chars scroll lda $07c1,x ;inside the loop sta $07c0,x ;continuously. inx cpx #40 ;40 chars row bne scroll messread lda scrolltext ;Check if @ is cmp #$00 ;detected ... bne nowrap lda #<scrolltext ;Reset text sta messread+1 ;for scroll lda #>scrolltext ;text. sta messread+2 jmp messread nowrap sta $07e7 inc messread+1 bne endscr inc messread+2 endscr rts ;Interrupts for the title screen tirq1 asl $d019 ;SYNC interrupt lda $dc0d ;-------------- sta $dd0d lda #raspos2 ;Second raster sta $d012 lda xpos ;Smooth scroll at sta $d016 ;bottom of screen lda #$01 sta delaytime;Add 1 Sync timer lda #<tirq2 ;Point low and hi sta $0314 ;bits to next lda #>tirq2 ;interrupt TIRQ2 sta $0315 pla ;Infinite loop tay pla tax pla rti tirq2 asl $d019 ;Do same as above lda #raspos3 ;3rd raster set sta $d012 lda #$08 ;No smooth scroll sta $d016 ;or multicolour lda #<tirq3 ;Point to next sta $0314 ;interrupt TIRQ3 lda #>tirq3 sta $0315 pla tay pla tax pla rti tirq3 asl $d019 ;Third interrupt lda #raspos4 ;4th raster sta $d012 lda xpos ;Smooth scroll sta $d016 jsr musicplay ;Play music lda #<tirq1 ;Point back to sta $0314 ;interrupt1 lda #>tirq1 sta $0315 pla ;Inifinite loop tay pla tax pla rti ;Main game code. GAMESTART. gamestart sei ;Put all of the colour data into the ;COLOUR RAM ($d800). The picture's ;colour RAM data lies at $5800. I used ;VIDCOM paint for this example. ldx #$00 setcolrs lda $5800,x sta $d800,x lda $5900,x sta $d900,x lda $5a00,x sta $da00,x lda $5ae8,x sta $dae8,x inx bne setcolrs ;Draw the status chars on to the bottom ;of the screen. Text must be fixed ;to display correctly. ldx #$00 drawstatus lda status,x cmp #$3f ;If lower case then bcc statok ;no change. sec sbc #$40 statok sta $07c0,x lda #$0e ;Light blue text sta $dbc0,x inx cpx #$28 ;40 chars bne drawstatus ;Enable sprites on screen. Also allow ;multicolour lda #$ff sta $d015 ;Sprites on sta $d01c ;Sprite MCOL on ;Setup the main 2 outline colours for ;every single sprite. lda #$0b sta $d025 ;Spr. Mcol 1 lda #$01 sta $d026 ;Spr. Mcol 2 ;Now setup the sprite position ghost ;regs as a start up. ldx #$00 setupspr lda dfltpos,x sta objpos,x inx cpx #$10 bne setupspr ;Also setup the default frame for the ;sprites. Because of the sprites ;appearing on the space background (A ;VIDCOM bitmap). The SCREEN SPRITE RAM ;at $5FF8-$5FFF is being used for the ;main sprite type. Also we are setting ;up the default sprite colours for ;everything. ldx #$00 setsprdflt lda dfltframe,x sta $5ff8,x lda dfltcols,x sta colourstore,x inx cpx #$08 bne setsprdflt ;Initialise all game pointers so we ;can default this game. (See pointers ;to understand what those are). lda #$00 ;Initialize all. sta animdelay ;pointers. sta animpointer sta planet1hit sta planet2hit sta planet3hit sta planet4hit sta planet5hit sta planet6hit sta explodedelay sta explodeptr sta randcounter sta firebutton sta planettime sta dirpointer sta planetdir lda #$03 ;Start frame sta explodestore ;explosion lda #1 ;Default sta planet1speed ;speed for lda #2 ;all planets. sta planet2speed lda #3 sta planet3speed lda #4 sta planet4speed lda #3 sta planet5speed lda #2 sta planet6speed ;Set low+hi byte pointers to the IRQ ;raster interrupt vectors. lda #<irq1 sta $0314 lda #>irq1 sta $0315 ;Initialise raster position lda #raspos1 sta $d012 ;Setup CIA Timers lda #$7f sta $dc0d ;Screen enabled lda #$1b sta $d011 ;Delay interrupt registers to slow ;things down a little. lda #$01 sta $d01a ror $d019 cli ;Clear IRQ flag ;This is our main in game loop. Sync ;timer and call additional routines. mainloop lda #$00 sta delaytime cmp delaytime beq *-3 jsr expandpos jsr moveplayer jsr movebullet jsr moveplanets jsr animation jsr collision jmp mainloop ;Expand the sprite positions and ;correctly display them in place to the ;hardware sprite registry. expandpos ldx #$00 exploop lda objpos+1,x sta $d001,x lda objpos+0,x asl a ror $d010 sta $d000,x inx inx cpx #$10 bne exploop rts ;Control the player using a joystick ;plugged into port 2. moveplayer ldy #$02 ;Default ship sty $5ff8 ;frame. (Ship front) lda $dc00 ;Read joystick p2 lsr a bcs notup ldx objpos+1 ;Move player up dex dex cpx #$32 bcs upok ldx #$32 upok stx objpos+1 notup lsr a bcs notdown ldx objpos+1 ;Move player down inx inx cpx #$d0 bcc downok ldx #$d0 downok stx objpos+1 notdown lsr a bcs notleft ldy #$00 ;Ship tilts left sty $5ff8 ldx objpos ;Move ship left dex cpx #$0c bcs leftok ldx #$0c leftok stx objpos notleft lsr a bcs notright ldy #$01 ;Ship tilts right sty $5ff8 ldx objpos ;Move ship right inx cpx #$a2 bcc rightok ldx #$a2 rightok stx objpos ;When pressing fire, the player cannot ;autofire when shooting a laser. This ;is where the BIT firebutton and ROR ;firebutton command takes place. notright lsr a bit firebutton ror firebutton bmi notfire bvc notfire ;Is the bullet still on screen and ;moving. If so, then ignore the ;process, else disable the button ;pressed. Until released again. ldy objpos+2 cpy #$00 bne lockfire ldy objpos sty objpos+2 ldy objpos+1 sty objpos+3 lockfire lda #$00 sta firebutton notfire rts ;Test the player's bullet to see if ;it is enabled. If so, then the bullet ;can move. Otherwise ignore it! movebullet ldy objpos+3 dey ;A few of these are for dey ;speed. dey dey dey dey dey dey dey dey dey dey cpy #$0b ;Offset bcs notoffset ldy #$00 sty objpos+2 notoffset sty objpos+3 rts ;Call subroutines to move planets. Last ;time, we used a loop. This time round ;since there are going to be different ;things occuring to the game. We are ;going to use a subroutine for each ;planet. Mainly to test each planet. moveplanets jsr timemovement jsr testplanet1 jsr testplanet2 jsr testplanet3 jsr testplanet4 jsr testplanet5 jsr testplanet6 rts ;Time X movement of the planets. ;Default = 0 timemovement lda planettime cmp #$a8 beq movedir inc planettime rts movedir lda #$00 sta planettime ldx dirpointer lda dirtable,x sta planetdir inx cpx #25 beq resetpdir inc dirpointer rts resetpdir ldx #$00 stx dirpointer rts ;Test the first planet. If planet is ;hit. Don't let it move. Otherwise ;allow it to animate and move. Other ;Planet tests are exactly the same. testplanet1 lda planet1hit ;Planet hit? cmp #$01 beq destroyplanet1 lda planetstore1;Animate sta $5ffa lda objpos+4 clc adc planetdir sta objpos+4 ;Move X-POS lda objpos+5 ;Move Y-POS clc adc planet1speed cmp #$fa bcc p1ok jmp resetplan1 p1ok sta objpos+5 rts destroyplanet1 jsr explode ;Blow up lda explodestore;Planet sta $5ffa ldx explodeptr cpx #7 beq resetplan1 rts resetplan1 jsr randomizer lda randspeed sta planet1speed lda randpos sta objpos+4 lda #$00 sta objpos+5 sta planet1hit rts ;Now test the second planet testplanet2 lda planet2hit cmp #$01 beq destroyplanet2 lda planetstore2 sta $5ffb lda objpos+6 clc adc planetdir sta objpos+6 lda objpos+7 clc adc planet2speed cmp #$fa bcc p2ok jmp resetplan2 p2ok sta objpos+7 rts destroyplanet2 jsr explode lda explodestore sta $5ffb ldx explodeptr cpx #7 beq resetplan2 rts resetplan2 jsr randomizer lda randspeed sta planet2speed lda randpos sta objpos+6 lda #$00 sta objpos+7 sta planet2hit rts ;Now test the third planet testplanet3 lda planet3hit cmp #$01 beq destroyplanet3 lda planetstore3 sta $5ffc lda objpos+8 clc adc planetdir sta objpos+8 lda objpos+9 clc adc planet3speed cmp #$fa bcc p3ok jmp resetplan3 p3ok sta objpos+9 rts destroyplanet3 jsr explode lda explodestore sta $5ffc ldx explodeptr cpx #7 beq resetplan3 rts resetplan3 jsr randomizer lda randpos sta objpos+8 lda randspeed sta planet3speed lda #$00 sta objpos+9 sta planet3hit rts ;Test the forth planet testplanet4 lda planet4hit cmp #$01 beq destroyplanet4 lda planetstore4 sta $5ffd lda objpos+10 clc adc planetdir sta objpos+10 lda objpos+11 clc adc planet4speed cmp #$fa bcc p4ok jmp resetplan4 p4ok sta objpos+11 rts destroyplanet4 jsr explode lda explodestore sta $5ffd ldx explodeptr cpx #7 beq resetplan4 rts resetplan4 jsr randomizer lda randpos sta objpos+10 lda randspeed sta planet4speed lda #$00 sta objpos+11 lda #$00 sta planet4hit rts ;Test the fith planet testplanet5 lda planet5hit cmp #$01 beq destroyplanet5 lda planetstore5 sta $5ffe lda objpos+12 clc adc planetdir sta objpos+12 lda objpos+13 clc adc planet5speed cmp #$fa bcc p5ok jmp resetplanet5 p5ok sta objpos+13 rts destroyplanet5 jsr explode lda explodestore sta $5ffe ldx explodeptr cpx #7 beq resetplanet5 rts resetplanet5 jsr randomizer lda randpos sta objpos+12 lda randspeed sta planet5speed lda #$00 sta objpos+13 sta planet5hit rts ;Test the last planet testplanet6 lda planet6hit cmp #$01 beq destroyplanet6 lda planetstore6 sta $5fff lda objpos+14 clc adc planetdir sta objpos+14 lda objpos+15 clc adc planet6speed cmp #$fa bcc p6ok jmp resetplan6 p6ok sta objpos+15 rts destroyplanet6 jsr explode lda explodestore sta $5fff ldx explodeptr cpx #$07 beq resetplan6 rts resetplan6 jsr randomizer lda randspeed sta planet6speed lda randpos sta objpos+14 lda #$00 sta objpos+15 sta planet6hit rts ;Position randomizer (Count 25 times) randomizer ldx randcounter lda randtable,x sta randpos lda randspeedtable,x sta randspeed inx cpx #25 beq resetrand inc randcounter rts resetrand ldx #$00 stx randcounter rts ;Animation for explosion routine explode lda explodedelay cmp #$02 beq expfast inc explodedelay rts expfast lda #$00 sta explodedelay ldx explodeptr lda explodetable,x sta explodestore inx cpx #$06 beq stopexplode inc explodeptr rts stopexplode ldx #$07 stx explodeptr rts ;Animation for main enemy sprites animation lda animdelay cmp #$04 beq fastenough inc animdelay rts fastenough lda #$00 sta animdelay ldx animpointer lda planetframe1,x sta planetstore1 lda planetframe2,x sta planetstore2 lda planetframe3,x sta planetstore3 lda planetframe4,x sta planetstore4 lda planetframe5,x sta planetstore5 lda planetframe6,x sta planetstore6 inx cpx #$06 beq resetframe inc animpointer rts resetframe ldx #$00 stx animpointer rts ;Test the sprite to sprite collision collision jsr tbullcol jsr tplayercol jsr planetcol1 jsr planetcol2 jsr planetcol3 jsr planetcol4 jsr planetcol5 jsr planetcol6 rts ;Test the bullet to see if it hits ;the enemies, using a box co-ords type ;collision (see swo #20). tbullcol lda objpos+2 sec sbc #$06 sta collstore clc adc #$0c sta collstore+1 lda objpos+3 sec sbc #$0c sta collstore+2 clc adc #$18 sta collstore+3 rts tplayercol lda objpos sec sbc #$06 sta collstore+4 clc adc #$0c sta collstore+5 lda objpos+1 sec sbc #$0c sta collstore+6 clc adc #$18 sta collstore+7 nocoll rts ;To make a fair collision for each of ;the planets. If a planet is exploding ;we ensure that no collision is made ;for that particular planet. Simply by ;jumping straight to the end of the ;RETURN TO SUBROUTINE command (RTS). planetcol1 lda planet1hit cmp #$01 beq nothit1b lda objpos+4 cmp collstore bcc nothit1a cmp collstore+1 bcs nothit1a lda objpos+5 cmp collstore+2 bcc nothit1a cmp collstore+3 bcs nothit1a jmp killplanet1 nothit1a lda objpos+4 cmp collstore+4 bcc nothit1b cmp collstore+5 bcs nothit1b lda objpos+5 cmp collstore+6 bcc nothit1b cmp collstore+7 bcs nothit1b jmp playerhit nothit1b rts planetcol2 lda planet2hit cmp #$01 beq nothit2b lda objpos+6 cmp collstore bcc nothit2a cmp collstore+1 bcs nothit2a lda objpos+7 cmp collstore+2 bcc nothit2a cmp collstore+3 bcs nothit2a jmp killplanet2 nothit2a lda objpos+6 cmp collstore+4 bcc nothit2b cmp collstore+5 bcs nothit2b lda objpos+7 cmp collstore+6 bcc nothit2b cmp collstore+7 bcs nothit2b jmp playerhit nothit2b rts planetcol3 lda planet3hit cmp #$01 beq nothit3b lda objpos+8 cmp collstore bcc nothit3a cmp collstore+1 bcs nothit3a lda objpos+9 cmp collstore+2 bcc nothit3a cmp collstore+3 bcs nothit3a jmp killplanet3 nothit3a lda objpos+8 cmp collstore+4 bcc nothit3b cmp collstore+5 bcs nothit3b lda objpos+9 cmp collstore+6 bcc nothit3b cmp collstore+7 bcc nothit3b jmp playerhit nothit3b rts planetcol4 lda planet4hit cmp #$01 beq nothit4b lda objpos+10 cmp collstore bcc nothit4a cmp collstore+1 bcs nothit4a lda objpos+11 cmp collstore+2 bcc nothit4a cmp collstore+3 bcs nothit4a jmp killplanet4 nothit4a lda objpos+10 cmp collstore+4 bcc nothit4b cmp collstore+5 bcs nothit4b lda objpos+11 cmp collstore+6 bcc nothit4b cmp collstore+7 bcs nothit4b jmp playerhit nothit4b rts planetcol5 lda planet5hit cmp #$01 beq nothit5b lda objpos+12 cmp collstore bcc nothit5a cmp collstore+1 bcs nothit5a lda objpos+13 cmp collstore+2 bcc nothit5a cmp collstore+3 bcs nothit5a jmp killplanet5 nothit5a lda objpos+12 cmp collstore+4 bcc nothit5b cmp collstore+5 bcs nothit5b lda objpos+13 cmp collstore+6 bcc nothit5b cmp collstore+7 bcs nothit5b jmp playerhit nothit5b rts planetcol6 lda planet6hit cmp #$01 beq nothit6b lda objpos+14 cmp collstore bcc nothit6a cmp collstore+1 bcs nothit6a lda objpos+15 cmp collstore+2 bcc nothit6a cmp collstore+3 bcs nothit6a jmp killplanet6 nothit6a lda objpos+14 cmp collstore+4 bcc nothit6b cmp collstore+5 bcs nothit6b lda objpos+15 cmp collstore+6 bcc nothit6b cmp collstore+7 bcs nothit6b jmp playerhit nothit6b rts ;The player has been hit by a planet ;therefore damage points will of course ;be taken off the player's shield. playerhit jsr drainshield jsr drainshield rts drainshield dec shieldval+2 ldx #$03 drainloop lda shieldval+0,x cmp #$2f bne shieldok lda #$39 sta shieldval+0,x dec shieldval-1,x shieldok dex bne drainloop ;Check if the shield is below 000 lda shieldval+0 cmp #$2f beq shipdoomed rts ;The player ship is doomed. So now we ;blow the ship up in a cool way. shipdoomed lda #$30 sta shieldval+0 ;zero counter sta shieldval+1 sta shieldval+2 lda #$00 sta explodedelay ldx #$00 stx explodeptr doomloop lda #$00 sta delaytime cmp delaytime beq *-3 lda #$01 sta $d017 ;expand x and 7 sta $d01d jsr expandpos jsr destroyplayer jmp doomloop destroyplayer lda explodedelay cmp #$02 beq delayfast inc explodedelay rts delayfast lda #$00 sta explodedelay ldx explodeptr lda explodetable,x sta $5ff8 inx cpx #6 beq finishedexp inc explodeptr rts finishedexp ldx #$00 stx explodeptr lda #$00 sta $d015 ;Copy the player's score from the ;screen ram. directly over to the ;game over message. ldx #$00 copyscore lda scoreval,x sta finalscore,x inx cpx #6 bne copyscore ldx #$00 copyend lda deadmsg,x cmp #$3f bcc msgok sec sbc #$40 msgok sta $07c0,x inx cpx #$28 bne copyend ;Now see if the player's score has ;beaten the top score. lda finalscore+5 sec lda topscore+5 sbc finalscore+5 lda topscore+4 sbc finalscore+4 lda topscore+3 sbc finalscore+3 lda topscore+2 sbc finalscore+2 lda topscore+1 sbc finalscore+1 lda topscore+0 sbc finalscore+0 bpl nohiscore ;High score achieved so this will ;final score will become the new high ;score, before jumping back to the ;front end. ldx #$00 puthi lda finalscore,x sta topscore,x inx cpx #6 bne puthi nohiscore lda #$00 sta firebutton gameover ;Wait for the player to press fire ;to play again. waitfire lda $dc00 lsr a lsr a lsr a lsr a lsr a bit firebutton ror firebutton bmi waitfire bvc waitfire jmp titlescreen ;The player successfully shot the first ;planet. So engage destruction mode. killplanet1 ldx #$00 stx explodeptr lda #$01 sta planet1hit jsr score jmp removebullet killplanet2 ldx #$00 stx explodeptr lda #$01 sta planet2hit jsr score jmp removebullet killplanet3 ldx #$00 stx explodeptr lda #$01 sta planet3hit jsr score jmp removebullet killplanet4 ldx #$00 stx explodeptr lda #$01 sta planet4hit jsr score jmp removebullet killplanet5 ldx #$00 stx explodeptr lda #$01 sta planet5hit jsr score jmp removebullet killplanet6 ldx #$00 stx explodeptr lda #$01 sta planet6hit jsr score removebullet ldx #$00 stx objpos+2 rts ;Player scores points per planet shot score inc scoreval+4 ldx #$04 scloop lda scoreval+0,x cmp #$3a bne scoreok lda #$30 sta scoreval+0,x inc scoreval-1,x scoreok dex bne scloop rts ;The first main interrupt. This will ;switch the sync timer on (delaytime). irq1 asl $d019 lda $dc0d sta $dd0d lda #raspos2 sta $d012 lda #$01 ;See TIRQ sta delaytime lda #<irq2 sta $0314 lda #>irq2 sta $0315 pla tay pla tax pla rti ;The next interrupt will display the ;bitmap picture. irq2 asl $d019 lda #raspos3 sta $d012 lda #$3b ;Bitmap mode sta $d011 lda #$18 ;Multicolour on sta $d016 lda #$78 ;Read VideoRAM $5c00 sta $d018 lda #$02 sta $dd00 ;VIC BANK #$02 lda #$00 sta $d01b ;Sprites in front lda #$ff sta $d01c ;Sprite multicolour ;on. ldx #$00 setcols2 lda colourstore,x ;Sprite cols sta $d027,x ;set inx cpx #8 bne setcols2 lda #<irq3 sta $0314 lda #>irq3 sta $0315 pla tay pla tax pla rti ;This interrupt will display the status ;bar at the bottom of the screen. The ;VIC Bank $03 is used, and charset is ;at $2000, so we use $18. Screen ;multicolour is disabled. Also mask the ;sprites to go behind the status bar ;invisibly irq3 asl $d019 lda #raspos4 sta $d012 lda #$08 sta $d016 lda #$18 sta $d018 lda #$03 sta $dd00 lda #$00 sta $d01c lda #$ff sta $d01b lda #$1b sta $d011 ldx #$00 makecols lda #$00 sta $d027,x inx cpx #8 bne makecols lda #<irq1 sta $0314 lda #>irq1 sta $0315 jsr $1003 pla tay pla tax pla rti ;Status panel for the game: status .text "score: 000" .text "000 -plan" .text "et popper" .text "!- [: 100" ;Death message for game over deadmsg .text "ship destr" .text "oyed - fin" .text "al score w" .text "as: " finalscore .text "000000" topscore .text "000000" ;Default sprite frame table. dfltframe .byte $02,$0e,$0a,$0a .byte $0a,$0a,$0a,$0a ;Sprite colour table dfltcols .byte $09,$01,$07,$03 .byte $0e,$05,$04,$0d ;Position table dfltpos .byte $58,$d0 ;Player start .byte $00,$00 ;Bullet start .byte $20,$00 ;Planet 1 .byte $30,$00 ;Planet 2 .byte $40,$00 ;Planet 3 .byte $50,$00 ;Planet 4 .byte $60,$00 ;Planet 5 .byte $a0,$00 ;Planet 6 ;Animation frame tables for sprites planetframe1 .byte $0d,$08,$09,$0a .byte $0b,$0c planetframe2 .byte $0c,$0d,$08,$09 .byte $0a,$0b planetframe3 .byte $0b,$0c,$0d,$08 .byte $09,$0a planetframe4 .byte $0a,$0b,$0c,$0d .byte $08,$09 planetframe5 .byte $09,$0a,$0b,$0c .byte $0d,$08 planetframe6 .byte $08,$09,$0a,$0b .byte $0c,$0d explodetable .byte $03,$04,$05,$06 .byte $10,$10,$10,$10 ;Random position and speed tables randtable .byte $10,$98,$30,$20,$a0 .byte $48,$60,$80,$78,$28 .byte $50,$38,$20,$60,$10 .byte $88,$90,$30,$18,$50 .byte $48,$a0,$58,$20,$90 randspeedtable .byte $01,$04,$02,$03,$05 .byte $04,$01,$02,$03,$03 .byte $01,$03,$04,$01,$02 .byte $03,$02,$03,$04,$01 .byte $05,$01,$04,$03,$01 dirtable .byte $00,$00,$01,$01,$ff .byte $ff,$00,$00,$02,$02 .byte $fe,$fe,$01,$01,$ff .byte $ff,$00,$00,$01,$01 .byte $02,$02,$fe,$fe,$01 .byte $01,$ff,$ff,$02,$02