[Scummvm-devel] Re: Transparency in OSystem

Marcus Comstedt marcus at mc.pp.se
Sun Apr 3 13:56:24 CEST 2005


Max Horn <max at quendi.de> writes:

> One reason we didn't use alpha channels, and will never be able to
> rely on their existance, is that for some of our targets, the overlays
> are purely 8 bit.
>
> We will have to keep clearOverlay (although it indeed should be
> renamed to grabOverlay) for this very reason

Yes, I know.  I didn't remove anything, just added the _possibility_
to have an overlay with real alpha, making the management much easier.
As it turned out, it was possible to have both variants in the same
"system", only the blending code needs to be duplicated because it
works differently depending on whether you have alpha or not (even
though the visual result is the same).  On 8 bit systems, blendRect
is just an alias for fillRect, the blending code is #ifdef:ed out, so
for them nothing has changed at all.


  // Marcus







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