Angus Dorbie (dorbie++at++sgi.com)
Tue, 26 Oct 1999 15:46:27 -0700
With multisample transparency you have order invariance when drawing
transparent objects and this is particularly usefull for trees and other
billboard-like rendering, the blending isn't required.
The performance penalty for this is likely to be a marginal fill
performance cost depending on the details of the state and visual
you are using and the platform.
Blended fill is more expensive but more widely available on lower end
systems.
Cheers,Angus.
"Mason D. Menninger" wrote:
>
> I have a question regarding rgba vs rgb textures. I was
> hoping someone could give me an idea of what kind of
> performance hit I should expect if I use four channel
> instead of three channel textures. I know it involves
> more than just disk space and memory usage. Alpha makes
> the scene more complicated to sort. But how much more
> work do these factors add to rendering the world when
> using Performer?
>
> The answer is probably scene specific, so here's a little
> info about what I'm dealing with. I typically have a few
> very large textures (1024x1024 to 256x256) that include
> alpha. There are usually three or four of these textures
> placed on the same number of tiles that are essentially
> co-planer. There are a few bits of geometry here and
> there but the tiles compose the bulk of the scene.
>
> So what kind of damage am I doing if I choose to use
> the alpha channel in this manner?
>
> -Mason
> mason++at++praxis.jsc.nasa.gov
>
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This archive was generated by hypermail 2.0b2 on Tue Oct 26 1999 - 15:46:47 PDT