_SETALPHA Question

[SMcNeill]

You can always do something like this, if you really just need to change alpha for a whole range at once for a _RGB color:

Code: (Select All)

OPTION _EXPLICIT

SCREEN _NEWIMAGE(640, 480, 32)





'|

'| Fade in a red box test

'|



DIM RedBox AS LONG

DIM c AS INTEGER



RedBox = _NEWIMAGE(320, 240, 32)

_DEST RedBox

CLS , _RGB32(255, 0, 0)

_DEST 0



c = 0

DO

    CLS

    _LIMIT 30

    ChangeAllAlpha c, _RGB32(255, 0, 0), RedBox

    _PUTIMAGE (159, 119), RedBox

    _DISPLAY

    _LIMIT 30

    c = c + 1

LOOP UNTIL c = 256



SUB ChangeAllAlpha (Alpha AS _UNSIGNED _BYTE, Kolor AS _UNSIGNED LONG, Image AS LONG)

    DIM AS _MEM m

    DIM AS _OFFSET o

    DIM AS _UNSIGNED _BYTE r, r1, g, g1, b, b1

    m = _MEMIMAGE(Image)

    r = _RED32(Kolor): g = _GREEN32(Kolor): b = _BLUE32(Kolor)

    o = m.OFFSET

    $CHECKING:OFF

    DO UNTIL o >= m.OFFSET + m.SIZE

        _MEMGET m, o + 2, r1

        _MEMGET m, o + 1, g1

        _MEMGET m, o, b1

        IF r = r1 AND g = g1 AND b = b1 THEN _MEMPUT m, o + 3, Alpha

        o = o + 4

    LOOP

    $CHECKING:ON

    _MEMFREE m

END SUB