Just to give an update on compression in VRML. Mime defines a compression
capability. There's an "enc=" field in a mime entry in addition to the
"type=" field. This means you can have a file that is both compressed and
mime typed. The 2 compression types I've seen are x-compress and x-gzip.
The "x-" prefix means they are not standard, so support is not
guaranteed. Netsite definitely supports them (.gz for x-gzip, and .Z for
x-compress) and the stock CERN server does not. But I know of at least
one person who has successfully gotten the CERN server to ship the enc
field intact.
If you have netsite (or the CERN server with the properly munged
mime.types file) then giving a VRML file of the form "foo.wrl.gz" will
ship out the mime type of "x-world/x-vrml" and the encoding type of
"x-gzip".
The browser writers need to support this encoding type field and "do the
right thing", i.e. - "gzip -d" the file, then treat it like normal vrml
data.
I've not seen any other vrml browsers, but I know that in the beta 1
version of WebSpace this is broken because the implementor of this feature
(i.e. - me) was using an old version of gzip for testing. WebSpace Beta 2
will fix this.
I've gotten 3 data points (myself and people at 2 other locations) and
we've all seen similar compression ratios - 8:1 on most files. I feel
this this is sufficient to obviate the need for a binary vrml format.
I don't know where any formal documentation of the above encoding
information resides or how to get a particular server on a particular
platform to recognize the compression suffixes. Any help from anyone else
on this matter???
--
chris marrin Silicon http://www.sgi.com/Products/WebFORCE/WebSpace
(415) 390-5367 Graphics ," http://reality.sgi.com/employees/cmarrin/
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