Metasprite animation definition

metasprite_defs.asm

MACRO nb_cels
    REDEF NB_CELS equs "_NB_CELS\@"
    db {NB_CELS}
    DEF {NB_CELS} = 0
ENDM
MACRO cel
    db (\1) ; Amount of frames to display this cel during
    REDEF {NB_CELS} = {NB_CELS} + (\1)
    dw (\2) ; Ptr to cel
ENDM

PlayerDownWalkingDraw:
    nb_cels ; Total animation length (it wraps after this)
    cel $10, PlayerDownStandingFrame
    cel $10, .frame0
    cel $10, PlayerDownStandingFrame
    cel $10, .frame1
    ; (it would be nice to also guarantee that $40 = $10 + $10 + $10 + $10 somehow)

MACRO nb_objs
    REDEF _NUM_OBJS EQUS "_NUM_OBJS_\@"
    db {_NUM_OBJS}
    DEF {_NUM_OBJS} = 0
ENDM
MACRO obj
    db (\1), (\2), (\3), (\4) ; y, x, tile, attr
    REDEF {_NUM_OBJS} = {_NUM_OBJS} + 1
ENDM

    dw PlayerDownWalkingTiles ; ... the player is a bit special, ignore this
.frame0
    nb_objs
    obj -27, -12, 0, 0 ; (-12, -27) from the actor position, which is between its feet
    obj -27,  -4, 2, 0
    obj -27,   4, 4, 0
    obj -11,  -8, 6, 0
    obj -11,   0, 8, 0