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

[Max Horn]

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