Hi Brett, You need to read up about deriving your own custom std::streambuf, once you understand this part then adapting existing plugins to use your encrypted stream will be straightforward. You could even be lazy a use a stringstream like the curl plugin does. Please look into this stuff - this will answer your need, and there is certainly no need to subclass from plugins, C++ std::stream streambuf extensibility exist to help solve problem like yours, and the OSG takes advantage of this.
Robert. On Wed, Oct 1, 2008 at 9:27 PM, brettwiesner <[EMAIL PROTECTED]> wrote: > Hey Robert, > > I'm confused about what you mean here. Many plugins have read/ write methods > that take istreams/ ostreams (ReaderWriterIVE being one of them). However, > since I can't subclass them I can't attach to the stream. For example, in > ReaderWriterIVE::writeNode() a std::ofstream is created but there's no way > for me to attach it to a stream buffer. > > It seems like the osga plugin would have the same problem. The doread()/ > dowrite() methods call up to whatever ReaderWriter was passed in and I can't > subclass those. > > Thanks, > Brett > > Robert Osfield wrote: >> >> Hi Brett, >> >> A number of the plugins support reading a writing from istream/ostream >> which means you can implement your std::streambuffer and attach to the >> stream and then pass this to the plugin. This technique allows you to >> do items like compression/decompression/encription/decription. Have a >> look at the osga and curl plugins as they provide examples of using >> streams this way. >> >> Robert. >> >> On Wed, Oct 1, 2008 at 5:02 PM, brettwiesner <[EMAIL PROTECTED]> >> wrote: >> >>> >>> Hi, >>> >>> I've got a requirement to ship certain 3rd party model data only in an >>> encrypted format. So I wrote my own loader that does the encryption/ >>> decryption but uses the IVE loader for everything. This works except for >>> files that reference other files. The master file is encrypted, but the >>> referenced files are saved out as .ive's. >>> >>> Ideally all I would have to do is subclass ReaderWriterIVE and override >>> the >>> following stream methods: >>> >>> virtual osgDB::ReaderWriter::ReadResult readObject(std::istream& fin, >>> const osgDB::ReaderWriter::Options* options) const; >>> >>> virtual osgDB::ReaderWriter::ReadResult readImage(std::istream& fin, >>> const osgDB::ReaderWriter::Options* options) const; >>> >>> virtual osgDB::ReaderWriter::ReadResult readNode(std::istream& fin, >>> const osgDB::ReaderWriter::Options* options) const; >>> >>> virtual osgDB::ReaderWriter::WriteResult writeObject(const osg::Object& >>> object, >>> std::ostream& fout, const osgDB::ReaderWriter::Options* options) >>> const; >>> >>> virtual osgDB::ReaderWriter::WriteResult writeImage(const osg::Image& >>> image, >>> std::ostream& fout, const osgDB::ReaderWriter::Options* options) >>> const; >>> >>> virtual osgDB::ReaderWriter::WriteResult writeNode(const osg::Node& >>> node, >>> std::ostream& fout, const osgDB::ReaderWriter::Options* options) >>> const; >>> >>> For writing I could get the raw data from the ive loader encrypt it and >>> write it out. For reading I could decrypt the data, then pass the >>> unencrypted data up to the ive loader for use. >>> >>> There is one fatal flaw... I can't subclass the ReaderWriterIVE plugin. >>> :( >>> >>> 1) Has anyone besides me ever wanted to derive from a file loader? Would >>> it >>> make sense to keep the logic in a lib with headers, then have another >>> library that is just the plugin? >>> >>> 2) Is there some other mechanism in OSG that will let me do this? >>> >>> Thanks, >>> Brett >>> _______________________________________________ >>> osg-users mailing list >>> osg-users@lists.openscenegraph.org >>> http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org >>> >>> >> >> _______________________________________________ >> osg-users mailing list >> osg-users@lists.openscenegraph.org >> http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org >> > > _______________________________________________ > osg-users mailing list > osg-users@lists.openscenegraph.org > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org > _______________________________________________ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
