Quick Demo stack for creating Transpanrecy effect.

[jbv]

Chipp,

I was wrong : you can't set transparent pixels using the "replace"
function (actually I thought that the 1st byte of each pixel was used
for the alpha channel, but it's just zero).

But you can try the following script which uses the offset function.
With the image in your example, it's roughly 28 times faster :

on mouseUp
  set cursor to watch
  lock screen
  put binaryEncode("C",0) into a
  put a into b
  repeat 3 times
    put binaryEncode("C",255) after a
  end repeat

  put imagedata of img 2 into IMD
  put alphadata of img 2 into AD
  put 0 into sk
  repeat forever
    put offset(a,IMD,sk) into c
    if c=0 then
      exit repeat
    else
      add c+3 to sk
      put b into char sk/4 of AD
    end if
  end repeat
  set alphadata of img 2 to AD
end mouseUp

JB

> Chipp,
>
> one more question : have you tried to use the replace function for
> groups
> of 4 bytes in the imagedata to speed up things, instead of checking
> binary values
> in the imagedata and then setting each byte of the alphadata ?
>
> best,
> JB
>
> > Helping out a friend, I did this. It could be good for a number of
> > things including:
> >
> > Creating cursors
> > Creating transparent GIFs
> > etc..
> >
> > in the messagebox:
> >
> > go URL "http://www.altuit.com/webs/altuit2/RunRev/altMakeTrans.rev"
> >
> > altMakeTransparent
> > This is a small demo stack which has a neat function which can make a
> > specific color transparent in an image.
> >
> > The demo makes all white pixels transparent. The function is in the
> > script of the button, "Make White Transparent"
> >
> > -Chipp
> >
> > _______________________________________________
> > use-revolution mailing list
> > use-revolution at lists.runrev.com
> > http://lists.runrev.com/mailman/listinfo/use-revolution
>
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