Re: [Plib-devel] PLIB developers needed.

[Gil C. <g.c...@ca...>]

At 06:35 PM 8/21/00 -0500, you wrote:
>Christian Mayer wrote:
>
> > > It certainly does use clip-texture - that's why they wrote that 
> particular
> > > demo.
> >
> > Sorry, but what's the clip-texture really doing?
>
>Clip texture is lots of things - but essentially it allows you to have
>a 'virtual' texture map that is *MASSIVE* - perhaps 1,000,000 x 1,000,000
>texels.  Since that's impossibly large, you are allowed to write into just
>some sections at the highest MIPmap level - and others at lower levels -
>and where there are gaps it can fill in.
>
>Urgh - that's a terrible explanation - but essentially, it allows you
>much more freedom in paging texture from disk efficiently.

To get it from SGI themselves:

"IRIS Performer on InfiniteReality® allows you to create textures that are 
much bigger than will fit in texture memory and even in system memory, so 
that you can fit your entire world in a single texture. IRIS Performer will 
also manage all of the texture loading for you from disk to system memory 
and then to texture memory, based on your current position in the database. 
IRIS Performer provides for virtual memory for very large Mip-mapped 
textures by only storing potentially visible texels in system and texture 
memory. Efficient management of texture memory is made possible by special 
capabilities of the InfiniteReality texturing hardware. This general 
technique is called clipmapping and is the subject of the rest of this paper"

The paper which they're referring to is at 
http://www.sgi.com/software/performer/presentations/clipmap_intro.pdf

Rgds,

Gil