Mario Veraart (rioj7++at++fel.tno.nl)
Wed, 8 Apr 1998 14:46:45 +0200 (MET DST)
My experience is that if you disable the flattening of loaded flight
geometry there will be only one copy of externals in memory.
I haven't tried instancing to see the results.
You can do this with perfly with the option
perfly -y,1,0 myfile.flt
Look at the tree to see how the geometry is stored.
In your program with
pfdConverterMode("flt", PFFLT_FLATTEN, FALSE);
Mario
Andy Walker wrote:
>
> Hello Donna
>
> I am not sure how Performer deals with the OpenFlight construct of
> external references and instances. My experience in the past was that
> externals and instances are turned into unique elements in memory not
> just pointers to one piece of memory. So in this case a flight file
> with a lot of externals and instances could grow much larger.
>
> Does your database use external references and instances extensively?
>
> Andy Walker
>
> > -----Original Message-----
> > From: Angus Dorbie [SMTP:dorbie++at++sgi.com]
> > Sent: Tuesday, April 07, 1998 2:15 PM
> > To: Steve Baker
> > Cc: Allen, Donna N; 'SGI Performer Users Group'; Reynolds, Berton
> > Subject: Re: Too Big?
> >
> > Steve Baker wrote:
> > >
> > > On Tue, 7 Apr 1998, Allen, Donna N wrote:
> > >
> > > > hi,
> > > >
> > > > I'm trying to load a 152MB Open Flight database with about 150 KB
> > of
> > > > texture into perfly on an Indigo 2 Extreme with 250 MH processor
> > and 256
> > > > MB Ram. I crashes with a memory allocation error. I would think
> > 256MB
> > > > ram would be enough for this. Is this too big?
> > >
> > > Sounds like it. You are assuming that the size of a '.flt' file on
> > disk
> > > is somehow a 1:1 correspondance with the amount of memory that a
> > similar
> > > Performer data structure will consume in main memory. This is very
> > far
> > > from the truth (although I confess that I don't know what the actual
> > > ratio is likely to be).
> >
> > A flt file should take up much less memory than disk space in
> > Performer.
> >
> > However textures are not embeded in the OpenFlight file format and
> > you'd
> > have to add those to memory useage so what I just said is probably
> > untrue
> > for many textured databases. And during the loading phase a texture
> > will exist in main memory, in OpenGL, plus MIP maps. Ultimately
> > you won't have a host copy but you still have a copy in system memory
> > in the GL even if it's currently downloaded to texture memory.
> >
> > Cheers,Angus.
> >
> > --
> > "Only the mediocre are always at their best." -- Jean Giraudoux
> >
> > For advanced 3D graphics Performer + OpenGL based examples and tutors:
> > http://www.dorbie.com/
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