Sharon Clay (src++at++rose.asd.sgi.com)
Mon, 26 Aug 1996 13:43:44 -0700
Clipmapping is simply a way of virtualizing texture
memory so that you can have a mipmapped texture of virtual size up
to 32Kx32K texels (that was on iR 6.2 with Perfomrer2.1 - it is getting much
bigger with more recent iR software) and yet use under 40MBytes of texture memory
(might be less depending on how you configure things).
You can probably get interactive clipmapping runing in a day and the
real-time 30/60-Hz version only requires playing with the formatting of enough disks
so that the disk bandwidth can keep up with your flying speed and the iR
downloading rates.
Just using Performer2.1 perfly you can give yourself a basic clipmapping demo on your
own data and even on your own database!
o There is clipmap documentation, data, and clipmap config files (file.ct)
under /usr/share/Performer/data/clipdata/ (**** see README in this dir !!!)
and tools to turn your data into clipmap data with rsets in
/usr/share/Performer/src/tools/
o You can run perfly on our and your clipmap data textured onto a single polygon
The /usr/share/Performer/data/clipdata/README shows how to do this.
Basically, it is just perfly file.im (where .im is the suffix for a
simple ascii loader that we ship).
perfly /usr/share/Performer/data/clipdata/moffett/mof.im will show you
1 meter data of Moffett Field.
o You can run perfly with our and your clipmap data replacing a texture
in _your_ database. From the perfly man page:
% setenv PFSUBSTCLIP_TEXTURE file.ct # needs to be in current dir or $PFPATH
% perfly your_datafile_fullname.substclip
That will just grab the first texture in your database and make it
a clipmap. You can select the texture by doing:
% setenv PFSUBSTCLIP_TEXTURE_I -1
- run perfly on database.substclip to get list of textures
and indices
% setenv PFSUBSTCLIP_TEXTURE_I tex_no
o There are simple programs under /usr/share/Performer/src/pguide/
to demonstrate different pieces of the clipmapping task:
pguide/libpr/C/{icache.c, cliptex.c}
We have more information about clipmapping in a document describing Performer2.1
features that I have put out on the ftp site:
ftp://sgigate.sgi.com/pub/Performer/docs/perf2.1.ps
We are working on the 2.2 release of Performer and if you would like
to develop a clipmapping application and are interested in being a 2.2 beta customer,
please let me know!
src.
--
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Sharon Rose Clay (Fischler) - Silicon Graphics, Advanced Systems Dev.
src++at++sgi.com (415) 933 - 1002 FAX: (415) 965 - 2658 MS 8U-590
http://www.sgi.com/Technology/Performer/
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