Re: [vox-tech] glide question

[Bill Broadley <MAPSbill@math.ucdavis.edu>]

On Thu, Apr 12, 2001 at 11:10:54AM -0700, Peter Jay Salzman wrote:
> can anyone who knows this stuff care to comment on this exchange?
> 
> who is right?
> 
> pete
> 
> 
> 
> 
> > 1. What is Glide?
> > 
> > Glide is a very low level, 3D API plus drivers that accesses 3D graphics
> > accelerator hardware based on chipsets manufactured by 3Dfx (these cards are
> > collectively called "Voodoo cards").

Completely correct.

>  A program can ONLY use the special
> > hardware acceleration features of your Voodoo board by using the Glide
> > library. 

Well, sort of, it's possible to access the hardware directly, but 3dfx
never made the specs public.  Kinda sad since the linux drivers have
always been fairly lame.

> If you want to use your Voodoo's capabilities, you must use Glide.
> > Glide supports little else besides defining a view point, displaying a
> > texture, and send tri's.
> 
> Not at all true. All 3dfx cards can do openGL, aswell.

3dfx cards can no do openGL, drivers can use the 3dfx card to enable
accelerated opengl functionality.  I.e. mesa+glide drivers.

> > There are some Glide features which resemble OpenGL, and some have no
> > counterpart.  Either way, the important point is: if you use OpenGL or a

Yes the glide designers were very familiar with opengl, some even
came from SGI's opengl group.  There are some striking similarities,
including possible texture sizes, formats and similar.

> > clone to perform some graphics task, it won't be hardware accelerated unless
> > that implementation makes use of Glide.

Well they could, but afaik none do.  So yes the way people have accelerated
3d with 3dfx cards is to use glide.

> Ummm. Basically, under X3, Mesa used glide to do OpenGL accelleration.
> But it was genuine openGL.

Hrm, well mesa is pretty much "genuine" openGl but at least for a long
time (not sure about today) it wasn't "certified" so couldn't actually
be called a opengl implementation.

> Under X4, the same is true, but instead, now, there's a unified
> drivery-thingy called DRI that can talk to your hardware under it's
> own steam without going via Glide. Glide is still available, but it's
> not used like that...

I believe it's just a matter of XF including the glide libs... although
maybe when I wasn't looking 3dfx actually opened up their hardware docs
enough to allow writing a decent 3d driver.