[osg-submissions] Support for reading images from an osgDB::Archive

[Robert Osfield]

Hi Glenn,

On Jan 21, 2008 2:19 PM, Glenn Waldron <gwaldron at gmail.com> wrote:
> Here is an example file:
>
> http://pelicanmapping.com/downloads/scene.osga

Thanks for the example.


>  This archive contains one .osg file and two textures. The .osg file
> references the textures by simple file names like "comm1.jpg". In order to
> see the textures, you will need the patch. (Side note: when you extract the
> osg file from the archive, the texture image filename is gone....not sure
> why.)

Can't say without testing it myself and digging into the code.

> FYI, the context here is my work on the osgGIS project, in which I am
> generating archives with huge numbers of buildings that need to share a
> (relatively) small collection of textures.

Yes this makes sense.  Although Ideally we'd actually have a even high
level feature for actually sharing the textures rather than just the
imagery... something for a future rev of the OSG.

>
> > It sounds like you are
> > actually specifying it as it is directory, which if a correct
> > assesement is a interesting way of doing things I haven't thought
> > about before.
>
> The concept of using archive name as directory already existed -- that's the
> first code block in Registry::read -- PagedLOD uses this by prepending the
> archive name into something like "file.osga/out.ive". The catch is that only
> PagedLOD does this, so it only works for paged node refs and not images.

Yes, an archive is conceptually a directory, just packed up into a single file.

>  My patch just checks the database path list for any archives and searches
> them for the referenced file. If it's not there, it continues on the normal
> search procedure.

I was actually hoping for a specific example illustrating it, my guess
reading this is that you could do something like:

  export OSG_FILE_PATH=/data/myarchive.osga
  osgviewer --image myimage.rgb

Where myimage.rgb can be found in the myarchive.osga.

Is this what you have in mind?

Robert.