/
checkforhiddenitems.asm
83 lines (79 loc) · 2.04 KB
/
checkforhiddenitems.asm
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CheckForHiddenItems:
; Checks to see if there are hidden items on the screen that have not yet been found. If it finds one, returns carry.
call GetMapScriptsBank
ld [wCurMapScriptBank], a
; Get the coordinate of the bottom right corner of the screen, and load it in wBottomRightYCoord/wBottomRightXCoord.
ld a, [wXCoord]
add SCREEN_WIDTH / 4
ld [wBottomRightXCoord], a
ld a, [wYCoord]
add SCREEN_HEIGHT / 4
ld [wBottomRightYCoord], a
; Get the pointer for the first bg_event in the map...
ld hl, wCurMapBGEventsPointer
ld a, [hli]
ld h, [hl]
ld l, a
; ... before even checking to see if there are any BG events on this map.
ld a, [wCurMapBGEventCount]
and a
jr z, .nobgeventitems
; For i = 1:wCurMapBGEventCount...
.loop
; Store the counter in wRemainingBGEventCount, and store the bg_event pointer in the stack.
ld [wRemainingBGEventCount], a
push hl
; Get the Y coordinate of the BG event.
call .GetFarByte
ld e, a
; Is the Y coordinate of the BG event on the screen? If not, go to the next BG event.
ld a, [wBottomRightYCoord]
sub e
jr c, .next
cp SCREEN_HEIGHT / 2
jr nc, .next
; Is the X coordinate of the BG event on the screen? If not, go to the next BG event.
call .GetFarByte
ld d, a
ld a, [wBottomRightXCoord]
sub d
jr c, .next
cp SCREEN_WIDTH / 2
jr nc, .next
; Is this BG event a hidden item? If not, go to the next BG event.
call .GetFarByte
cp BGEVENT_ITEM
jr nz, .next
; Has this item already been found? If not, set off the Itemfinder.
ld a, [wCurMapScriptBank]
call GetFarWord
ld a, [wCurMapScriptBank]
call GetFarWord
ld d, h
ld e, l
ld b, CHECK_FLAG
call EventFlagAction
ld a, c
and a
jr z, .itemnearby
.next
; Restore the bg_event pointer and increment it by the length of a bg_event.
pop hl
ld bc, BG_EVENT_SIZE
add hl, bc
; Restore the BG event counter and decrement it. If it hits zero, there are no hidden items in range.
ld a, [wRemainingBGEventCount]
dec a
jr nz, .loop
.nobgeventitems
xor a
ret
.itemnearby
pop hl
scf
ret
.GetFarByte:
ld a, [wCurMapScriptBank]
call GetFarByte
inc hl
ret