Re: Too Big?

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Angus Dorbie (dorbie++at++sgi.com)
Tue, 07 Apr 1998 14:15:08 -0700

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 


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