Re: Overhead for rendering multiple windows

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Angus Dorbie (dorbie++at++sgi.com)
Wed, 29 Jul 1998 06:51:41 -0700

Colin Bridgewater wrote:
>
> Angus Dorbie wrote:
> >
> > Colin Bridgewater wrote:
> >> ... the Performer Progammers' Guide states:
> >>> The use of multiple windows on a single graphics pipe can add
> >>> overhead. The sharing of the graphics context between windows
> >>> consumes almost all of this overhead.
> >> Would anyone care to be more specific as to what "almost" means ?
> > Well how much does a glViewport, glFrustum, a modelview loadmatrix,
> > a couple of matrix mode changes a glScissor and potentially another
> > glClear (quite reasonably ignoring the time taken to actually
> > perform the clear) cost?
>
> So, handling the X layer is done in hardware is it ?

It's the _SAME_ context!

X is out of the loop because you have a direct rendering context on SGI
when on the local display.

You're far too cynical :-)

Why don't you measure the difference if you can. It should be easy
if there's a large overhead right.

Cheers,Angus.

-- 
"Only the mediocre are always at their best." -- Jean Giraudoux 


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