; Tank›; Bill Kendrick 2015›  ›Byte Array PMG,PMGM,PMG0,PMG1,CHSET,SC›Byte Array Tank=[›  INCLUDE "TANKSPR.ACT"›]›INCLUDE "TANKMEM.ACT"››; No motion on input except every›; MaxSpd-th frame›Byte Spd,MaxSpd››; Players' directions & "been hit" ctr›Byte D0,D1,HIT0,HIT1››; Players' positions›Int X0,Y0,X1,Y1››; Whether to draw player this frame›Byte Draw0=[1],Draw1=[1] ››; Bullet "alive" counters & directions›Byte B0=[0],BD0,B1=[0],BD1 ››; Bullet positions›Int BX0,BY0,BX1,BY1››; Explosion sfx counter›Byte Expl=[0]››; X/Y deltas (shifted to positive)›; for player & bullet internal X/Y›; locations (which are right-shifted›; to become screen X/Y locations)›Int Array Delta=[  › 4 0› 5 1› 6 2› 7 3› 8 4› 7 5› 6 6› 5 7› 4 8› 3 7› 2 6› 1 5› 0 4› 1 3› 2 2› 3 1›]››; Meat of the game, all within a VBI!›Proc VBIDrawSprite()›  Byte I›  Int OX0,OY0,OX1,OY1›  Byte Pointer Src0Ptr,Src1Ptr›  Byte Pointer PMGY0,PMGY1,PMGYM››  SAVETEMPS››  ; Only handle user input & movement›  ; occasionally›  Spd=Spd+1›  If Spd>=MaxSpd Then›    Spd=0››    ; --- MOVE PLAYER 1 ---›    OX0=X0›    OY0=Y0››    ; Spin right or left from joy input›    ; (or auto spin if hit)›    If (STICK0 & 8)=0 Or HIT0>0 Then›      D0=(D0+1)&15›      Draw0=1›    ElseIf (STICK0 & 4)=0 Then›      D0=(D0-1)&15›      Draw0=1›    Fi››    ; Move forward on joy input›    ; (if not spinning due to hit)›    If HIT0=0 And (STICK0 & 1)=0 Then›      AUDC2=15 ; loud engine sfx››      X0=X0+Delta(D0 Lsh 1)-4›      Y0=Y0+Delta((D0 Lsh 1)+1)-4› ›      ; Don't go off-screen›      If X0<0 Or X0>604 Or Y0<0 Or Y0>244 Then›        X0=OX0›        Y0=OY0›      Else›        Draw0=1›      Fi›    Else›      If HIT0>0 Then›        If HIT0=32 Then›          ; On first contact w/ bullet,›          ; fly across the screen in›          ; direction of enemy's bullet››          PMGY0=PMG0+16+(Y0 Rsh 2)-2››          For I=0 To 7 Do›            PMGY0(I+2)=0›          Od››          OX0=X0›          OY0=Y0››          X0=X0+Delta(BD1 Lsh 1)-4›          Y0=Y0+Delta((BD1 Lsh 1)+1)-4››          If X0<0 Or X0>604 Or Y0<0 Or Y0>244 Then›            X0=OX0›            Y0=OY0›          Else›            Draw0=1›          Fi›        Fi››        ; Being-hit sfx›        AUDC2=HIT0 Rsh 2›        AUDF2=HIT0›        HIT0=HIT0-1›      Else›        ; Low engine idle sfx›        AUDC2=2›        AUDF2=200›      Fi›    Fi››    ; --- MOVE PLAYER 2 ---›    ; (see above)›    OX1=X1›    OY1=Y1››    If (STICK1 & 8)=0 Or HIT1>0 Then›      D1=(D1+1)&15›      Draw1=1›    ElseIf (STICK1 & 4)=0 Then›      D1=(D1-1)&15›      Draw1=1›    Fi› ›    If HIT1=0 And (STICK1 & 1)=0 Then›      X1=X1+Delta(D1 Lsh 1)-4›      Y1=Y1+Delta((D1 Lsh 1)+1)-4›      AUDC4=15› ›      If X1<0 Or X1>604 Or Y1<0 Or Y1>244 Then›        X1=OX1›        Y1=OY1›      Else›        Draw1=1›      Fi›    Else›      If HIT1>0 Then›        If HIT1=32 Then›          PMGY1=PMG1+16+(Y1 Rsh 2)-2››          For I=0 To 7 Do›            PMGY1(I+2)=0›          Od››          OX1=X1›          OY1=Y1››          X1=X1+(Delta(BD0 Lsh 1)-4) Lsh 3›          Y1=Y1+(Delta((BD0 Lsh 1)+1)-4) Lsh 3››          If X1<0 Or X1>604 Or Y1<0 Or Y1>244 Then›            X1=OX1›            Y1=OY1›          Else›            Draw1=1›          Fi›        Fi›        AUDC4=HIT1 Rsh 2›        AUDF4=HIT1›        HIT1=HIT1-1›      Else›        AUDC4=2›        AUDF4=200›      Fi›    Fi›  Fi››  ; --- DRAW PLAYER 1 ---›  If Draw0=1 Then›    ; Draw shape based on dir tank faces›    Src0Ptr=Tank+(D0 Lsh 3)››    ; Draw at tank's Y position›    PMGY0=PMG0+16+(Y0 Rsh 2)-2››    ; Erase above/below, draw in new pos›    PMGY0(0)=0›    PMGY0(1)=0›    For I=0 To 7 Do›      PMGY0(I+2)=Src0Ptr^›      Src0Ptr==+1›    Od›    PMGY0(10)=0›    PMGY0(11)=0››    ; Move to X position›    HPOSP0=(X0 Rsh 2)+48››    Draw0=0››    ; Bump backwards if we touch other›    ; tank, water, or brick›    If P0PL>0 Or (P0PF&2)=2 Or (P0PF&4)=4 Then›      OX0=X0›      OY0=Y0›      X0=X0-((Delta(D0 Lsh 1) Lsh 1)-8)›      Y0=Y0-((Delta((D0 Lsh 1)+1) Lsh 1)-8)›      If X0<0 Or X0>604 Or Y0<0 Or Y0>244 Then›        X0=OX0›        Y0=OY0›      Else›        Draw0=1›      Fi›    Fi›  Fi››  ; --- DRAW PLAYER 2 ---›  ; (see above)›  If Draw1=1 Then›    Src1Ptr=Tank+(D1 Lsh 3)›    PMGY1=PMG1+16+(Y1 Rsh 2)-2››    PMGY1(0)=0›    PMGY1(1)=0›    For I=0 To 7 Do›      PMGY1(I+2)=Src1Ptr^›      Src1Ptr==+1›    Od›    PMGY1(10)=0›    PMGY1(11)=0››    HPOSP1=(X1 Rsh 2)+48››    Draw1=0››    If P1PL>0 Or (P1PF&2)=2 Or (P1PF&2)=4 Then›      OX1=X1›      OY1=Y1›      X1=X1-((Delta(D1 Lsh 1) Lsh 1)-8)›      Y1=Y1-((Delta((D1 Lsh 1)+1) Lsh 1)-8)›      If X1<0 Or X1>604 Or Y1<0 Or Y1>244 Then›        X1=OX1›        Y1=OY1›      Else›        Draw1=1›      Fi›    Fi›  Fi››  ; --- PLAYER 1 FIRE ---››  ; If not hit, bullet not already in›  ; flight, and fire btn press, shoot!›  If HIT0+HIT1=0 And›     STRIG0=0 And B0=0 Then›    ; Set flight time, direction,›    ; and starting pos›    B0=64›    BD0=D0›    BX0=X0+8›    BY0=Y0+16›  Fi››  ; --- PLAYER 2 FIRE ---›  ; (see above)›  If HIT0+HIT1=0 And›     STRIG1=0 And B1=0 Then›    B1=64›    BD1=D1›    BX1=X1+8›    BY1=Y1+16›  Fi››  ; --- PLAYER 1 BULLET ---›  If B0>0 Then›    ; Erase in old position›    ; (missiles shared, so &ing vs›    ; just setting to 0)›    PMGYM=PMGM+16+(BY0 Rsh 2)›    PMGYM(0)=PMGYM(0)&252››    ; Move bullet›    BX0=BX0+Delta(BD0 Lsh 1)-4›    BY0=BY0+Delta((BD0 Lsh 1)+1)-4››    ; Countdown flight time›    B0=B0-1››    ; Stop bullet immediately if out of›    ; bounds›    If BX0<0 Or BX0>604 Or BY0<0 Or BY0>260 Then›      B0=0›    Fi››    ; Bullet sfx›    AUDC1=(B0 Rsh 2)››    ; If still alive, set new X pos›    ; and draw in new Y pos›    ; (missiles shared, so %ing vs›    ; just setting to 1)›    If B0>0 Then›      HPOSM0=(BX0 Rsh 2)+48›      PMGYM=PMGM+16+(BY0 Rsh 2)›      PMGYM(0)=PMGYM(0)%1›    Fi››    ; Now that it's drawn in new pos,›    ; check for detection...››    ; Touching opponent? Make them›    ; explode!›    If M0PL=2 Then›      B0=1 ;Will die next loop›      HIT1=32›      ; FIXME: Scoring›    Fi››    ; Touching brick? Destroy it!›    If M0PF=2 Then›      B0=1 ;Will die next loop›      SC((BY0 Rsh 5)*20+(BX0 Rsh 5))=2›      Expl=15›    Fi›  Else›    HPOSM0=0›  Fi››  ; Prepare for fresh collision›  ; detection during the next frame›  HITCLR=0››  ; Brick just exploded? Play sfx›  If Expl>0 Then›    Expl=Expl-1›    CONSOL=RANDOM›  Fi› ›  GETTEMPS›  XITVBV››; Enable our VBI›Proc VBIInit()›  CRITIC=1›  OldVBI=VVBLKD›  VVBLKD=VBIDrawSprite›  CRITIC=0›Return››; Disable our VBI›Proc ClearVBI()›  CRITIC=1›  VVBLKD=OldVBI›  CRITIC=0›Return››; Draw a random map›Proc DrawMap()›  Byte I,X,Y,X1,X2,Y1,Y2››  Zero(SC,240)››  ; River going down center(ish) of›  ; screen›  X=Rand(10)+5›  For Y=0 To 9 Do›    SC(Y*20+X)=130›    If X>0 And Rand(255)<64 Then›      X=X-1›    ElseIf X<19 And Rand(255)<64 Then›      X=X+1›    Fi›  Od››  ; Some random brick walls›  ; FIXME: This sucks›  For I=0 To 5 Do›    X1=Rand(20)›    X2=Rand(20)›    Y=Rand(10)›    For X=X1 To X2 Do›      SC(Y*20+X)=65›    Od››    X=Rand(20)›    Y1=Rand(10)›    Y2=Rand(10)›    For Y=Y1 To Y2 Do›      SC(Y*20+X)=65›    Od›  Od›Return››Proc Main()›  Byte I,B››  Graphics(2)›  ›  ; Some space for Player/Missile gfx›  ; and redefine character set›  PMG=RAMTOP-16›  PMBASE=PMG›  CHBAS=PMG+8››  ; Pointers to tops of PMG memory›  ; for missiles, P0, and P1›  PMG==*256›  PMGM=PMG+384›  PMG0=PMG+512›  PMG1=PMG+640››  ; Zero out PMG data›  Zero(PMG+384,384)››  ; Zero out charset data›  CHSET=PMG+2048›  Zero(CHSET+1024)››  ; Chset: Dirt›  Poke(CHSET+2,2)›  Poke(CHSET+4,32)›  Poke(CHSET+7,8)››  ; Chset: Brick›  Poke(CHSET+8,251)›  Poke(CHSET+9,251)›  Poke(CHSET+10,251)›  Poke(CHSET+12,223)›  Poke(CHSET+13,223)›  Poke(CHSET+14,223)››  ; Chset: Water/Explosion (the same)›  For I=16 To 31 Do›    B=Rand(255)›    Poke(CHSET+I,B)›  Od››  ; Find beginning of screen memory›  SC=SAVMSC››  ; PMG config›  GPRIOR=1  ; All PMGs above playfield›  SIZEP0=0  ; Narrow P0›  SIZEP1=0  ; Narrow P1›  SDMCTL=46 ; Std playfield (+2),›            ;   missile DMA (+4),›            ;   player DMA (+4),›            ;   screen DMA (+32)›  GRACTL=3  ; Enable players & missiles››  ; Players' starting state›  D0=0›  X0=1›  Y0=1›  HIT0=0››  D1=6›  X1=50›  Y1=50›  HIT1=0››  ; Movement speed›  MaxSpd=3››  ; Sound config›  AUDCTL=0 ; ???›  SKCTL=3  ; ???››  ; Default sounds›  AUDF1=40  ; Player 1 engine›  AUDC1=0›  AUDF2=200 ; Player 1 bullet›  AUDC2=0›  AUDF3=30  ; Player 2 engine›  AUDC3=0›  AUDF4=220 ; Player 2 bullet›  AUDC4=0››  ; Screen colors›  COLOR0=34  ; Yellow dirt›  COLOR1=70  ; Red bricks›  COLOR2=172 ; Blue water›  COLOR3=0   ; Black (unused)›  COLOR4=192 ; Dark green ground (bkgd)›  PCOLR0=220 ; Light yellow green P1›  PCOLR1=186 ; Light bluegreen P2››  ; Set up map & start game VBI›  DrawMap()›  VBIInit()››  ; Main program loop (outside VBI)›  CH=255›  DO›    ; FIXME: Do anything else? :)›  UNTIL CH=28 OD ; Exit loop on [Esc]›  CH=255››  ; End game VBI›  ClearVBI()››  GRACTL=0››  ; Silence sounds›  AUDCTL=0›  SKCTL=3›  AUDF1=0›  AUDC1=0›  AUDF2=0›  AUDC2=0›  AUDF3=0›  AUDC3=0›  AUDF4=0›  AUDC4=0›Return››