A C64 Game - Step 21

Now some more tidbits. A game is not complete without a neat title screen:


For now this is nothing more than a almost empty screen and a separate control loop. The loop simply waits for a button press and then jumps to the game main loop. Once the player lost all lives he is returned to the title loop.

Note that for both cases we also check if the button has been released before allowing to go forward. Nothing's more annyoing than accidental commencing.



Rather unspectacular, the title screen code. First the screen is displayed and then the check button loop entered. Once the button has been pressed the game variables are reset and the code runs into the main game loop.

;------------------------------------------------------------
;the title screen game loop
;------------------------------------------------------------
!zone TitleScreen
TitleScreen
          ldx #0
          stx BUTTON_PRESSED
          stx BUTTON_RELEASED
          sta VIC_SPRITE_ENABLE

          ;clear screen
          lda #32
          ldy #0
          jsr ClearScreen

          ;display title logo
          lda #<‍TEXT_TITLE
          sta ZEROPAGE_POINTER_1
          lda #>TEXT_TITLE
          sta ZEROPAGE_POINTER_1 + 1
          lda #0
          sta PARAM1
          lda #1
          sta PARAM2
          jsr DisplayText

          ;display start text
          lda #<‍TEXT_FIRE_TO_START
          sta ZEROPAGE_POINTER_1
          lda #>TEXT_FIRE_TO_START
          sta ZEROPAGE_POINTER_1 + 1
          lda #11
          sta PARAM1
          lda #23
          sta PARAM2
          jsr DisplayText

.TitleLoop
          jsr WaitFrame
          lda #$10
          bit $dc00
          bne .ButtonNotPressed

          ;button pushed
          lda BUTTON_RELEASED
          bne .Restart
          jmp .TitleLoop

.ButtonNotPressed
          lda #1
          sta BUTTON_RELEASED
          jmp .TitleLoop

.Restart
          ;game start values
          lda #3
          sta PLAYER_LIVES

          ;setup level
          jsr StartLevel
          lda #0
          sta LEVEL_NR
          jsr BuildScreen
          jsr CopyLevelToBackBuffer

;------------------------------------------------------------
;the main game loop
;------------------------------------------------------------

Of course the counter part needs to be added to the DeadControl routine. If the player lost his last life, return to the title screen:

!zone DeadControl
DeadControl
          lda SPRITE_ACTIVE
          beq .PlayerIsDead
          rts

.PlayerIsDead
          lda #$10
          bit $dc00
          bne .ButtonNotPressed

          ;button pushed
          lda BUTTON_RELEASED
          bne .Restart
          rts

.ButtonNotPressed
          lda #1
          sta BUTTON_RELEASED
          rts

.Restart
          ;if last live return to title
          lda PLAYER_LIVES
          bne .RestartLevel
          jmp TitleScreen

.RestartLevel

step21.zip