Did you notice the huge door in the background? It's about time it opens!
That's actually pretty simple. At the jump-to-next level code we add a check. Whether the open door animation is shown depends on a bit in the LEVEL_CONFIG byte.
GoToNextLevel
lda LEVEL_CONFIG
and #$04
beq .NoDoorAnim
jsr DoorAnim
.NoDoorAnim
The actual animation is straight forward. The door location is hard coded, and we simply copy the characters one step to the outer side and replace the innermost characters with empty space.
Notice that we use a method which is not possible that easy in todays code: We have a local code loop until the door is completely opened.
Since there are no events to be handled, messages to be retrieved or other OS specific code required, we can do that.
;------------------------------------------------------------
;open door animation
;------------------------------------------------------------
!zone DoorAnim
DoorAnim
lda #0
sta LEVEL_DONE_DELAY
.DoorAnimLoop
jsr WaitFrame
inc LEVEL_DONE_DELAY
lda LEVEL_DONE_DELAY
and #$07
bne .DoorAnimLoop
;open door (16,11)
lda #11
sta PARAM2
-
ldy PARAM2
lda SCREEN_LINE_OFFSET_TABLE_LO,y
sta ZEROPAGE_POINTER_1
lda SCREEN_LINE_OFFSET_TABLE_HI,y
sta ZEROPAGE_POINTER_1 + 1
ldy #17
lda (ZEROPAGE_POINTER_1),y
dey
sta (ZEROPAGE_POINTER_1),y
ldy #18
lda (ZEROPAGE_POINTER_1),y
dey
sta (ZEROPAGE_POINTER_1),y
ldy #19
lda (ZEROPAGE_POINTER_1),y
dey
sta (ZEROPAGE_POINTER_1),y
lda #32
ldy #19
sta (ZEROPAGE_POINTER_1),y
ldy #22
lda (ZEROPAGE_POINTER_1),y
iny
sta (ZEROPAGE_POINTER_1),y
ldy #21
lda (ZEROPAGE_POINTER_1),y
iny
sta (ZEROPAGE_POINTER_1),y
ldy #20
lda (ZEROPAGE_POINTER_1),y
iny
sta (ZEROPAGE_POINTER_1),y
lda #32
ldy #20
sta (ZEROPAGE_POINTER_1),y
inc PARAM2
lda PARAM2
cmp #21
bne -
;
lda LEVEL_DONE_DELAY
lsr
lsr
lsr
cmp #4
bne .DoorAnimLoop
;door is fully open now
-
jsr WaitFrame
inc LEVEL_DONE_DELAY
lda LEVEL_DONE_DELAY
cmp #200
bne -
rts
Also, since I'm going on vacation this tutorial takes a break until next year. Thanks for your support so far, have fun!
