terribleAssembly/src/animation.asm
2020-05-28 15:21:34 +12:00

156 lines
4.4 KiB
NASM

;----------------
; Animation Subs
;----------------
struct Actor
bytes 1, YPos
bytes 1, XPos
bytes 1, GFXCounter
bytes 1, GFXState
bytes 1, TileData
words 1, GFXData
end_struct
SECTION "Actor STructs", WRAM0
dstruct Actor, Player
dstruct Actor, NPC01
dstruct Actor, NPC02
dstruct Actor, NPC03
dstruct Actor, NPC04
dstruct Actor, NPC05
SECTION "Animation Variables", HRAM
hCameraX: dw
hCameraY: dw
hWorkingX: dw
hWorkingY: dw
hWorkingScreenX: db
hWorkingScreenY: db
hWorkingState: db
hWorkingCounter: db
hWorkingData: dw
hWorkingTile: db
SECTION "Animations Subs", ROM0
; RenderActor:
; takes a pointer to an actor struct
; and renders it to shadow OAM, advancinc
; the animation frame and constructing
; each frame as needed.
; initial input:
; [hl] <- start of Actor Struct in WRAM
; output:
; an oam object for each line in the frame data,
; copied to shadowOAM (wShadowOAM)
RenderActor::
; @input: hl <- Player
; @input: de <- ShadowOAM place
; clobbers af, bc, de, hl
ld a, [hli] ; a <- YPos
ldh [hWorkingScreenY], a
ld a, [hli] ; a <- XPos
ldh [hWorkingScreenX], a
push hl ; save counter pointer on stack
ld a, [hli] ; a <- GFXCounter
ldh [hWorkingCounter], a
ld a, [hli] ; a <- GFXState
ldh [hWorkingState], a
ld a, [hli] ; a <- TileData
ldh [hWorkingTile], a
ld a, [hli] ; a <- GFXData(Low)
ld h, [hl] ; a <- GFXData (High)
ld l, a
ld a, [hWorkingState] ; add actor struct offset saved in wWorkingState
rlca ; double state offset because of word length
add a, l
ld l, a
adc a, h
sub l
ld h, a ; hl contains state struct pointer
ld a, [hli] ;
ld h, [hl] ; derefence [hl]
ld l, a ;
ld a, [hWorkingCounter]
inc a
ld b, a
ld a, [hli] ; a <- state frame limit
cp b
ld a, b
jr nc, .continueAnimation
xor a
.continueAnimation
ldh [hWorkingCounter], a
ld b, h ;
ld c, l ; save current hl
pop hl ; restore counter wram pointer
ld [hl], a ;
ld h, b ; restore hl
ld l, c ;
ld c, a ; save current frame in c
xor a ; set a = 0
.loopFrameFind ;
ld b, a ; b <- current total
ld a, [hli] ; a <- next frame tick limit
add b ; add to limit
cp c ; compare to limit
jr nc, .foundFrame ; if no carry, cum total > current frame
inc hl
inc hl
jr .loopFrameFind
.foundFrame
ld a, [hli]
ld h, [hl]
ld l, a ; hl <- pointer to frame data
ld a, [hli]
ld b, a ; b <- sprite counter
.spriteLoop
ld a, [hli] ; load Y position, then offset by -16
ld c, a
ld a, [hWorkingScreenY]
add c
ld c, 16
add c
ld [de], a ; store YPos in shadowOAM
inc de
ld a, [hli] ; load X position, then offset by -8
ld c, a
ld a, [hWorkingScreenX]
add c
ld c, 8
add c
ld [de], a ; store XPos in shadowOAM
inc de
ld a, [hli] ; load tile offset, and add to base tile pointer
ld c, a
ld a, [hWorkingTile]
add c
ld [de], a
inc de
ld a, [hli] ; load attributes and xor them
ld c, a
ld a, 0 ; TO DO: set base attributes
xor c
ld [de], a
inc de
dec b ; end of single sprite
jr nz, .spriteLoop
ret