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_AdvancePlayerSprite::
ld a, [wSpritePlayerStateData1YStepVector]
ld b, a
ld a, [wSpritePlayerStateData1XStepVector]
ld c, a
ld hl, wWalkCounter ; walking animation counter
dec [hl]
jr nz, .afterUpdateMapCoords
; if it's the end of the animation, update the player's map coordinates
ld hl, wPikachuOverworldStateFlags
res 5, [hl]
ld a, [wYCoord]
add b
ld [wYCoord], a
ld a, [wXCoord]
add c
ld [wXCoord], a
.afterUpdateMapCoords
ld a, [wWalkCounter] ; walking animation counter
cp $07
jp nz, .scrollBackgroundAndSprites
; if this is the first iteration of the animation
ld a, c
cp $01
jr nz, .checkIfMovingWest
; moving east
ld a, [wMapViewVRAMPointer]
ld e, a
and $e0
ld d, a
ld a, e
add $02
and $1f
or d
ld [wMapViewVRAMPointer], a
jr .adjustXCoordWithinBlock
.checkIfMovingWest
cp $ff
jr nz, .checkIfMovingSouth
; moving west
ld a, [wMapViewVRAMPointer]
ld e, a
and $e0
ld d, a
ld a, e
sub $02
and $1f
or d
ld [wMapViewVRAMPointer], a
jr .adjustXCoordWithinBlock
.checkIfMovingSouth
ld a, b
cp $01
jr nz, .checkIfMovingNorth
; moving south
ld a, [wMapViewVRAMPointer]
add $40
ld [wMapViewVRAMPointer], a
jr nc, .adjustXCoordWithinBlock
ld a, [wMapViewVRAMPointer + 1]
inc a
and $03
or $98
ld [wMapViewVRAMPointer + 1], a
jr .adjustXCoordWithinBlock
.checkIfMovingNorth
cp $ff
jr nz, .adjustXCoordWithinBlock
; moving north
ld a, [wMapViewVRAMPointer]
sub $40
ld [wMapViewVRAMPointer], a
jr nc, .adjustXCoordWithinBlock
ld a, [wMapViewVRAMPointer + 1]
dec a
and $03
or $98
ld [wMapViewVRAMPointer + 1], a
.adjustXCoordWithinBlock
ld a, c
and a
jr z, .pointlessJump ; mistake?
.pointlessJump
ld hl, wXBlockCoord
ld a, [hl]
add c
ld [hl], a
cp $02
jr nz, .checkForMoveToWestBlock
; moved into the tile block to the east
xor a
ld [hl], a
ld hl, wXOffsetSinceLastSpecialWarp
inc [hl]
ld de, wCurrentTileBlockMapViewPointer
call MoveTileBlockMapPointerEast
jr .updateMapView
.checkForMoveToWestBlock
cp $ff
jr nz, .adjustYCoordWithinBlock
; moved into the tile block to the west
ld a, $01
ld [hl], a
ld hl, wXOffsetSinceLastSpecialWarp
dec [hl]
ld de, wCurrentTileBlockMapViewPointer
call MoveTileBlockMapPointerWest
jr .updateMapView
.adjustYCoordWithinBlock
ld hl, wYBlockCoord
ld a, [hl]
add b
ld [hl], a
cp $02
jr nz, .checkForMoveToNorthBlock
; moved into the tile block to the south
xor a
ld [hl], a
ld hl, wYOffsetSinceLastSpecialWarp
inc [hl]
ld de, wCurrentTileBlockMapViewPointer
ld a, [wCurMapWidth]
call MoveTileBlockMapPointerSouth
jr .updateMapView
.checkForMoveToNorthBlock
cp $ff
jr nz, .updateMapView
; moved into the tile block to the north
ld a, $01
ld [hl], a
ld hl, wYOffsetSinceLastSpecialWarp
dec [hl]
ld de, wCurrentTileBlockMapViewPointer
ld a, [wCurMapWidth]
call MoveTileBlockMapPointerNorth
.updateMapView
call LoadCurrentMapView
ld a, [wSpritePlayerStateData1YStepVector]
cp $01
jr nz, .checkIfMovingNorth2
; if moving south
call ScheduleSouthRowRedraw
jr .scrollBackgroundAndSprites
.checkIfMovingNorth2
cp $ff
jr nz, .checkIfMovingEast2
; if moving north
call ScheduleNorthRowRedraw
jr .scrollBackgroundAndSprites
.checkIfMovingEast2
ld a, [wSpritePlayerStateData1XStepVector]
cp $01
jr nz, .checkIfMovingWest2
; if moving east
call ScheduleEastColumnRedraw
jr .scrollBackgroundAndSprites
.checkIfMovingWest2
cp $ff
jr nz, .scrollBackgroundAndSprites
; if moving west
call ScheduleWestColumnRedraw
.scrollBackgroundAndSprites
ld a, [wSpritePlayerStateData1YStepVector]
add a
ld b, a
ld a, [wSpritePlayerStateData1XStepVector]
add a
ld c, a
; shift all the sprites in the direction opposite of the player's motion
; so that the player appears to move relative to them
ld hl, wSprite01StateData1YPixels
ld e, 15
.spriteShiftLoop
ld a, [hl]
sub b
ld [hli], a
inc l
ld a, [hl]
sub c
ld [hl], a
ld a, $0e
add l
ld l, a
dec e
jr nz, .spriteShiftLoop
.done
ldh a, [hSCY]
add b
ldh [hSCY], a ; update background scroll Y
ldh a, [hSCX]
add c
ldh [hSCX], a ; update background scroll X
ret
; the following four functions are used to move the pointer to the upper left
; corner of the tile block map in the direction of motion
MoveTileBlockMapPointerEast::
ld a, [de]
add $01
ld [de], a
ret nc
inc de
ld a, [de]
inc a
ld [de], a
ret
MoveTileBlockMapPointerWest::
ld a, [de]
sub $01
ld [de], a
ret nc
inc de
ld a, [de]
dec a
ld [de], a
ret
MoveTileBlockMapPointerSouth::
add MAP_BORDER * 2
ld b, a
ld a, [de]
add b
ld [de], a
ret nc
inc de
ld a, [de]
inc a
ld [de], a
ret
MoveTileBlockMapPointerNorth::
add MAP_BORDER * 2
ld b, a
ld a, [de]
sub b
ld [de], a
ret nc
inc de
ld a, [de]
dec a
ld [de], a
ret
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