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

[J.Brown (Ender/Amigo)]

I say, commit a patch using some form of RGBA for the actual overlay, but
ignore alpha for the time being.

We can do alpha easily enough in software, later on, but for the moment
alpha isn't a "Must have", just a feature that would be very nice to add
later on.

 - Ender

On Thu, 19 Sep 2002, Max Horn wrote:

> Date: Thu, 19 Sep 2002 13:42:37 +0200
> From: Max Horn <max at quendi.de>
> To: Marcus Comstedt <marcus at mc.pp.se>
> Cc: scummvm-devel at lists.sourceforge.net
> Subject: Re: [Scummvm-devel] On Overlays (portes please read!)
>
> At 13:21 Uhr +0200 19.09.2002, Marcus Comstedt wrote:
> >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.
>
> Yes we wannt single pixel alpha control, it seems. The problem is
> that this is supposed to work on all backends, and I don't think they
> all support ARBG4444, so while the DC port would be able to handle
> this nicely, other ports might have to emulate this in software...
>
>
> I will try to make all my changes into one big patch that I'll put on
> the patch tracker for public review. So that you guys can see what I
> actually did, and if you can indeed port it to your backend or not.
>
>
> Max
> --
> -----------------------------------------------
> Max Horn
> Software Developer
>
> email: <mailto:max at quendi.de>
> phone: (+49) 6151-494890
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