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Re: [ogl-sample] Future of the SI?

To: ogl-sample@xxxxxxxxxxx
Subject: Re: [ogl-sample] Future of the SI?
From: "Nathan D. Tuck" <nate@xxxxxxxxxxxxxxxxxxx>
Date: Thu, 27 Apr 2000 14:04:06 +0000 (GMT)
In-reply-to: <200004271257215.SM00160@KENDALLB> from "Kendall Bennett" at Apr 27, 2000 12:55:09 PM
Reply-to: ogl-sample@xxxxxxxxxxx
Sender: owner-ogl-sample@xxxxxxxxxxx
Hi,

As far as I remember from the last time I looked at the SI/Windows
code, this was not too hard since there were appropriate function
pointer tables for say cards that didn't do T&L, setup, or whatever.
Perhaps John just meant to say that doing this isn't necessarily a
fill in the blanks exercise?

Certainly a whole bundle of cards without T&L have used this codebase
to base their drivers on.

nate

> Sure, for the future and to support hardware T&L, the OpenGL API 
> really is the device driver layer for the most part. However although 
> all interesting new hardware has hardware T&L, there are still 
> literally millions of good boards out there in the field that don't 
> have this! Hence we need to way to ensure that we can provide good 
> solutions for legacy hardware (hell, are we *already* at the stage of 
> calling the TNT2 and Voodoo3 legacy hardware!).
> 
> So my idea is that we need a layered device driver model. One layer 
> is for cards with only 2D acceleration, and most does all the 
> rendering in software (with perhaps an accelerated screen clear and 
> 2D primitives ;-). The next layer is for rasterisation only hardware 
> and provides a device driver model for that. The next layer above 
> that is for harware T&L, where a large portion of the OpenGL API 
> functions go directly into the device driver layers (once you do all 
> the usual OS specific stuff for managing threads etc).
> 
> An abstract API for all this stuff is certainly possible. If it 
> wasn't, Direct3D immediate mode would not exist ;-)
> 
> Regards,
> 
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