As I' m also interested in texture compression my question is:
when using .osg files or ive files without texture inside (those
obtained by osgconv -O noTexturesInIVEFile useOriginalExternalReferences
foo.osg soo.ive)
if there is a chain of pagedlod files that refer to the same texture
(for example the same material texture is used for different files at
different lods)
does it get readed or loaded in txture memory several times?
I though it does not happen... but willing to be sure.
Instead, if it is embedded in ive, it is replicated.
Am I wrong?
Another question: could be feasible to store jpeg as S3TC_DXT* instead
of uncompressed?
I know it is not happening now... would it be hard to implement? are
there technical limitations?
it seem to me that other web enabled sw like Google Earth are
transmitting jpeg texture
I experimented once trying to call the same compression code in osgconv
inside the jpeg plugin after the read... but the code got unstable and slow.
Has anyone tried this and/or would it be of some interest?
Thanks in advance
Robert Osfield ha scritto:
Hi Yefei,
On Wed, Apr 1, 2009 at 4:24 PM, Yefei He <[email protected]
<mailto:[email protected]>> wrote:
Thanks for your reply. Yes, I agree it will take quite some
effort and possibly format change to implement texture sharing
between ive files with built-in textures. That's why I would like
a quicker way out:) -- using ive files without built-in texture but
refer to compressed texture in dds format. Is my assumption
correct that compressed texture in dds format remains compressed
when loaded into memory and passed on to the osg core and GL layer
without being decompressed, as opposed to say jpeg images which
are decompressed during loading and then passed on to osg core in
uncompressed bitmap format?
Yes this is correct, the OSG loads the S3TC_DXT* compressed formats
from the .dds file and keeps them in that format in the osg::Image and
the final downloaded texture. You can compress the textures for a
file using osgconv:
osgconv --compressed myfile.flt myfile.ive
It won't solve the problem of sharing textures though.
Robert.
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