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RE: DDraw Blt vs BltFast


Alexander,

Because the following article:

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/wcegmm/htm/
ddover_51.asp

states that:

"BltFast cannot be used on surfaces that have an attached clipper."

We use a clipper to account for any other Windows window overlaying our
window, which would cause a portion of our blit destiation to be
undrawable... which would mean that we wouldn't be allowed to use BltFast.

Now... could we use BltFast in DirectDraw fullscreen modes?  Probably... but
some coding would have to be done that prevents the clipper from being
allocated, and it would only give a (slight) performance boost if we wrote a
Windowed and FullScreen version of the shadow function (else we'd be doing
the if clipper test that Blt does but BltFast does not do).

I don't think that using BltFast would be worth the effort.  I'm going to
guess that you wouldn't see any measurable improvement, whatsoever.

But, you are welcome to try it...

Harold

> -----Original Message-----
> From: cygwin-xfree-owner@cygwin.com
> [mailto:cygwin-xfree-owner@cygwin.com]On Behalf Of Alexander Gottwald
> Sent: Monday, March 11, 2002 10:50 AM
> To: cygwin-xfree@sources.redhat.com
> Subject: DDraw Blt vs BltFast
>
>
> Hi,
>
> Is there any reason why we use Blt instead of BltFast for copying the
> shadow surface. I just searched the MSDN and found this article
> http://msdn.microsoft.com/library/default.asp?url=/library/en-us/w
cegmm/htm/ddover_52.asp

bye
	ago
--
 Alexander.Gottwald@informatik.tu-chemnitz.de
 http://www.gotti.org           ICQ: 126018723
 phone: +49 3725 349 80 80	mobile: +49 172 7854017


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