Message-Id: <3.0.1.32.19990216140256.0091b100@iut.ujf-grenoble.fr>
X-Sender: sletuffe AT iut DOT ujf-grenoble DOT fr
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Date: Tue, 16 Feb 1999 14:02:56 +0100
To: djgpp AT delorie DOT com
From: LETUFFE SYLVAIN <sletuffe AT iut DOT ujf-grenoble DOT fr>
Subject: Re: Line frame buffer speed problem
In-Reply-To: <36C82E49.FDA@club-internet.fr>
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Reply-To: djgpp AT delorie DOT com

>Hi!
>
>I have got a small problem.
>
>I have a graphic library(done with DJGPP offcourse) which
>I use in several applications.
>Well, I'm currently working on a 3D-viewer and the banked modes
>doesn't make life easy so I rebuilded it with mode-detection
>and LineFrameBuffer support.
>
>And performance dropped almost 70%...
>
>I have an old Matrox Millennium and I thought that maybe there
>were some drivers that wasn't up to date or something, so I got
>SciTech Display Doctor and it updated a lot of stuff, but
>still, the performance is really bad with LFB.
>
>The testvalues from SciTech Display Control Center:
>
>mode: 640x480x16bit: Banked
>
>Clr screen: 75Mb/sec
>BitBlt:     55Mb/sec
>
>mode: 640x480x16bit: Linear buffer
>
>Clr screen: 21Mb/sec
>BitBlt:     19Mb/sec

Well I have already heard of that problem with old matrox cards...
The Linear frame buffer is not well supported by that kind of cards... 
(sorry for you ! ... go back to banked buffer !)
Or else you could try to get univbe on the net...
It could help...

Well as a matter of fact could I get the source code of your graphical
library ??? please.
'cause I am also working on a 3D engine but only in bank switching mode and
I'd like to try the lfb as well...
How do you use the descriptor to lfb memory ? how do you know which adress
it is ?


Go on with your work ! (good luck...)
Could you just mail me a little explanation of how do you compute your
rotation (up-down)(left-right)?