QB64 Phoenix Edition
Would this "RbgaPset" be a way around not having _RGBA ? - Printable Version

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+--- Thread: Would this "RbgaPset" be a way around not having _RGBA ? (/showthread.php?tid=1930)

Would this "RbgaPset" be a way around not having _RGBA ? - CharlieJV - 08-22-2023

Implementing _RGBA in BAM would be, I think, I real nightmare.

Instead, I'm thinking better to set an include library with this "RgbaPset" function.  Question is: am I right in thinking this yields the same as what _RGBA  would do color-wise ?

Code: (Select All)
SUB RgbaPset(x,y,r,g,b,a)
    c = POINT(x,y)
    c$ = RIGHT$("000000" + HEX$(c), 6)
    cr = VAL("0x" + LEFT$(c$,2)) * 256 ^ 2
    cg = VAL("0x" + MID$(c$,3,2)) * 256 ^ 1
    cb = VAL("0x" + RIGHT$(c$,2))
    PSET(x,y), { [cr * (255-a)/255 + r * a / 255] _
                + [cg * (255-a)/255 + g * a / 255] _
                + [cb * (255-a)/255 + b * a / 255] }
END SUB

screen 27

line (0,0) - (400,400), &h0000ff ,BF

FOR this_x = 50 to 150
FOR this_y = 50 to 150

RgbaPset(this_x,this_y,0,0,0,100)

next this_y
next this_x


RE: Would this "RbgaPset" be a way around not having _RGBA ? - bplus - 08-22-2023

(08-22-2023, 06:16 PM)CharlieJV Wrote: Implementing _RGBA in BAM would be, I think, I real nightmare.

Instead, I'm thinking better to set an include library with this "RgbaPset" function.  Question is: am I right in thinking this yields the same as what _RGBA  would do color-wise ?

Code: (Select All)
SUB RgbaPset(x,y,r,g,b,a)
    c = POINT(x,y)
    c$ = RIGHT$("000000" + HEX$(c), 6)
    cr = VAL("0x" + LEFT$(c$,2)) * 256 ^ 2
    cg = VAL("0x" + MID$(c$,3,2)) * 256 ^ 1
    cb = VAL("0x" + RIGHT$(c$,2))
    PSET(x,y), { [cr * (255-a)/255 + r * a / 255] _
                + [cg * (255-a)/255 + g * a / 255] _
                + [cb * (255-a)/255 + b * a / 255] }
END SUB

screen 27

line (0,0) - (400,400), &h0000ff ,BF

FOR this_x = 50 to 150
FOR this_y = 50 to 150

RgbaPset(this_x,this_y,0,0,0,100)

next this_y
next this_x

Yeah I think I translated your code to QB64 and compared your method, Charlie, with normal way of drawing an Alpha rectangle in QB64.

No blinking between 2 methods demos that it works. I tried a few colors too.
Code: (Select All)
Screen _NewImage(800, 600, 32)
Do
    Cls
    Line (0, 0)-(400, 400), &HFF0000FF, BF

    For this_x = 50 To 150
        For this_y = 50 To 150

            RgbaPset this_x, this_y, 255, 255, 0, 100

        Next this_y
    Next this_x
    _Delay 1
    _Display


    Cls
    Line (0, 0)-(400, 400), &HFF0000FF, BF
    Line (50, 50)-(150, 150), _RGB32(255, 255, 0, 100), BF
    _Delay 1
    _Display

Loop Until _KeyDown(27)

Sub RgbaPset (x, y, r, g, b, a)
    Dim c As _Unsigned Long
    c = Point(x, y)
    cr = _Red32(c)
    cg = _Green32(c)
    cb = _Blue32(c)
    PSet (x, y), _RGB32(cr * (255 - a) / 255 + r * a / 255, cg * (255 - a) / 255 + g * a / 255, cb * (255 - a) / 255 + b * a / 255)
End Sub

Nice one, assuming I did it correctly.

RE: Would this "RbgaPset" be a way around not having _RGBA ? - CharlieJV - 08-22-2023

Arg!  I was in hockey puck mode and forgot to "rgb" the color for the PSET statement in the sub.

This works:

Code: (Select All)
' This only works with BAM modes 23 to 27
' Not meant to be used with any other modes

SUB RgbaPset(x,y,r,g,b,a)
    c = POINT(x,y)
    c$ = RIGHT$("000000" + HEX$(c), 6)
    cr = VAL("0x" + LEFT$(c$,2)) * 256 ^ 2
    cg = VAL("0x" + MID$(c$,3,2)) * 256 ^ 1
    cb = VAL("0x" + RIGHT$(c$,2))
    PSET(x,y), _rgb( [cr * (255-a)/255 + r * a / 255], _
                    [cg * (255-a)/255 + g * a / 255], _
                    [cb * (255-a)/255 + b * a / 255] )

END SUB

screen 27

line (0,0) - (400,400), &h0000ff ,BF

FOR this_x = 50 to 150
    FOR this_y = 50 to 150
        RgbaPset(this_x,this_y,255,255,0,255)
    next this_y
next this_x


RE: Would this "RbgaPset" be a way around not having _RGBA ? - CharlieJV - 08-22-2023

And here it is: https://www.reddit.com/r/BASICAnywhereMachine/comments/15yle1r/prototyping_an_rgbapset_subroutine/

BTW: Truth be told, I'm on this because I really want to get @Dav 's Space Orbs working in BAM.  Without that alpha-blending, what I did get working is pretty psychedelic.

RE: Would this "RbgaPset" be a way around not having _RGBA ? - CharlieJV - 08-24-2023

Another little test program.  After the screen fills up with a bunch of wee orbs, half of the screen has a gradient overlay of alpha-blended (?) blue: