[Scummvm-devel] On Overlays (portes please read!)

Marcus Comstedt marcus at mc.pp.se
Thu Sep 19 04:24:03 CEST 2002


Max Horn <max at quendi.de> writes:

> >   The hardware will handle
> >alpha blending, so no problem with that even on a moving background.
> 
> Nope, it won't be able to handle the alpha blending. How should it be
> able to do it when we only have one bit of alpha mask? So to be able
> to do it, I am right now doing the alpha blending in the old way (only
> change is that now we don't blend using a palette anymore).

You can specify a floating point alpha value for the entire overlay.
Or separate alpha values for the corners and have it interpolated.
Did you want single pixel alpha control?  That can be arranged also,
using ARGB4444 pixel format.  But then you'll of course only have
12-bit colour, not 16-bit.


  // Marcus






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