Re: [Linux-fbdev-devel] Alpha blending

[Geert U. <ge...@li...>]

On Mon, 2 Apr 2001, Scott A McConnell wrote:
> I assume the Transp is for Alpha blending.
> It appears that the  API can support Alpha blending at the pixel level.
> 
> What about support at the rectangular level?
> 
> Not that they are an authority.... ;-)
> 
> http://www.pcwebopedia.com/TERM/a/alpha_channel.html
> 
> "Typically, you wouldn't define the alpha channel on a pixel-by-pixel
> basis, but rather per object. Different parts of the object would have
> different levels of transparency depending on how much you wanted the
> background to show through. This allows you to
> create rectangular objects that appear as if they are irregular in shape
> -- you define the rectangular edges as transparent so that the
> background shows through. This is especially important for animation,
> where the background changes from one frame to the next. "

That's something different. `transp' in fbdev is about transparency of the
screen (for a video underlay or so), not about transparency of objects to be
blended together on the screen.

> Wouldn't we want an Alpha/Transp value to be passed to the three
> accelerated functions?

No, we don't want transparant text consoles :-)

Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- ge...@li...

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
							    -- Linus Torvalds