Re: [osg-users] How do I Subclass a file loader?
Hi Brett, You can override the reading and writing at a high level by doing using a Registry::ReadFileCallback and WriteFileCallback. You could use this to intercept all the the write of .ive and adapt them. Or just disable the change the ProxyNode's filename so that it includes an extension relating to your encrypted format. The other approach is to leave all the loaders as is, and just encrypted the vertex and image data. This would require an encryption that doesn't change the data size, but would enable you to use all the loaders as is, and just run a visitor over the scene grpah and decrypt/encrypt. Robert. On Fri, Oct 3, 2008 at 9:38 PM, brettwiesner <[EMAIL PROTECTED]> wrote: > OK. I have a workaround for my problem. I'll explain the original problem, > my solution and make a suggestion. > > Requirements: > A third party we have bought models from does not what their data to be > shipped unencrypted. So I have to encrypt it. > > Initial Solution: > My thought was that I'd like to just use the IVE loader to write a node to a > stream, then I'd encrypt that thereby getting an encrypted fast loading > file. So I tried that. I wrote a loader that use the IVE loader to get a > stream from a node, then I encrypted the stream and wrote it out. The loader > would also read in an encrypted file, decrypt it into a stream and pass that > into the IVE loader. All was well until I came across models with proxy > nodes (aka models that referenced other models). > > It turns out the IVE loader writes out .ive files for all it's proxy nodes. > There are several options that I can pass to the IVE loader that will make > it not write out external references, but I want it to. I just don't want > them to be written out as ".ive's"; I want them to be written out as my > encrypted file format. > > Workaround: > Because loaders don't have API's they can't be subclassed. Instead, I had to > do a little trickery. I'll use encryption as an example. When my loader is > active (ie: writing an encrypted file), I remove the real IVE loader from > the ReaderWriter list in the registry (but I keep around a pointer to it). I > register my loader as something that accepts the ".ive" extension. Now when > anyone tries to write out an ".ive" file, they will be using my loader. > Then I use the pointer to the real IVE loader to write the node to a > stream. When the IVE loader comes across a proxy node and wants to write out > an ".ive" file, it asks the registry for the IVE loader, which then gives it > back my loader. My loader gets the stream from the real IVE loader then does > the encryption and writes it out. At the end, my loader adds the real IVE > loader back to the reader writer list and then changed itself to no longer > accept ".ive's" as a valid extension. > > My suggestion: > This trickery could have been avoided if the logic for the IVE loader was in > a library that could be extended. The IVE loader has a little helper class > for every kind of node in OSG. These classes should be created with a > factory. Then I could subclass the IVE loader and replace the ProxyNode > helper class with my subclass and I'd be able to have an encrypted loader > that lives alongside the real IVE loader without any weird tricks. > > Imagine a library... osgDbIve. This would have headers in the include dir, a > lib in the lib dir, a dll in the bin dir. Then there would be one other > library, osgDB_ive which would be very small and only build the plugin. > Users could then subclass the loader logic since that is all contained in an > extendable API, and just write the small loader plugin . > > 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
Re: [osg-users] How do I Subclass a file loader?
OK. I have a workaround for my problem. I'll explain the original problem, my solution and make a suggestion. Requirements: A third party we have bought models from does not what their data to be shipped unencrypted. So I have to encrypt it. Initial Solution: My thought was that I'd like to just use the IVE loader to write a node to a stream, then I'd encrypt that thereby getting an encrypted fast loading file. So I tried that. I wrote a loader that use the IVE loader to get a stream from a node, then I encrypted the stream and wrote it out. The loader would also read in an encrypted file, decrypt it into a stream and pass that into the IVE loader. All was well until I came across models with proxy nodes (aka models that referenced other models). It turns out the IVE loader writes out .ive files for all it's proxy nodes. There are several options that I can pass to the IVE loader that will make it not write out external references, but I want it to. I just don't want them to be written out as ".ive's"; I want them to be written out as my encrypted file format. Workaround: Because loaders don't have API's they can't be subclassed. Instead, I had to do a little trickery. I'll use encryption as an example. When my loader is active (ie: writing an encrypted file), I remove the real IVE loader from the ReaderWriter list in the registry (but I keep around a pointer to it). I register my loader as something that accepts the ".ive" extension. Now when anyone tries to write out an ".ive" file, they will be using my loader. Then I use the pointer to the real IVE loader to write the node to a stream. When the IVE loader comes across a proxy node and wants to write out an ".ive" file, it asks the registry for the IVE loader, which then gives it back my loader. My loader gets the stream from the real IVE loader then does the encryption and writes it out. At the end, my loader adds the real IVE loader back to the reader writer list and then changed itself to no longer accept ".ive's" as a valid extension. My suggestion: This trickery could have been avoided if the logic for the IVE loader was in a library that could be extended. The IVE loader has a little helper class for every kind of node in OSG. These classes should be created with a factory. Then I could subclass the IVE loader and replace the ProxyNode helper class with my subclass and I'd be able to have an encrypted loader that lives alongside the real IVE loader without any weird tricks. Imagine a library... osgDbIve. This would have headers in the include dir, a lib in the lib dir, a dll in the bin dir. Then there would be one other library, osgDB_ive which would be very small and only build the plugin. Users could then subclass the loader logic since that is all contained in an extendable API, and just write the small loader plugin . Thanks, Brett ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] How do I Subclass a file loader?
brettwiesner wrote on Thursday, October 02, 2008 2:22 PM:
> Jean,
>
> I did try my original solution which is how I know it writes out .ive
> files. I also just implemented the visitor solution to see what happens.
> As expected, the visitor goes and changes the names of all the
> referenced files. Then the top level file is written out. The proxy
> nodes try to write themselves out but since the files they reference
> ("referencedFile.eive") doesn't exist, nothing is written out.
>
> I would need to be able to change the proxy node ReadWrite class which
> is the part of the IVE loader that says to write out proxy nodes as
> "ive" files. This would require me to derive from ReaderWriterIVE and
> subclass the ProxyNode class so it writes out an "enc" file instead of
> an "ive" file.
Looking at ReaderWriterIVE, it looks like PagedLOD doesn't even try to write
its children (unless they are already loaded), so if that's what you've got in
your database, you'll have to manually encrypt its referenced files.
If you've got ProxyNodes, it looks like you can disable automatic writing of
its referenced files by putting "noWriteExternalReferenceFiles" into the
Options; then you can manually encrypt the referenced files (you'd still have
to changed the referenced filenames to "eive"). This would be a workaround to
subclassing ReaderWriterIVE.
I think the existing mechanisms to do this are not very pretty (and
inconsistent between ProxyNode and PagedLOD), so if you would like to suggest
improvements, that would be great!
> Jean-Sébastien Guay wrote:
>> Hi Brett,
>>
>> I'm wondering, if you suspect that ProxyNodes (and thus PagedLOD nodes
>> as well) would be a problem, why don't you just run a visitor that
>> would find those, and change their extension to eive (or whatever you
>> want)? Then if you write the top-level file, it will write the
>> referenced files with the right writer, and they will be re-read correctly
>> as well...
>>
>> Or, try it without and see what happens. If what you suspect turns out
>> to be true, then you have a possible solution above, but if it all
>> works like magic you won't have wasted any time.
>>
>> Hope this helps,
>>
>> J-S
>
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FlightSafety International
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Re: [osg-users] How do I Subclass a file loader?
Hi,
I'm going to try one more thing... In my readerWriter, I can unregister
the real IVE loader, and register my "encrypted ive" loader. This way,
my loader gets called when a ".ive" is written out/ read in. I'll
actually call the real IVE loader for all read and writes, but the
recursive proxy node writer will ask the registry for the readerWriter
associated with an ".ive" file and it will get give it my EIVE loader.
When it's all done, I'll re-register the IVE loader with the ".ive"
extension.
I'll let you know what happens...
Thanks,
Brett
Jean-Sébastien Guay wrote:
Hi Brett,
As expected, the visitor goes and changes the names of all the
referenced files. Then the top level file is written out. The proxy
nodes try to write themselves out but since the files they reference
("referencedFile.eive") doesn't exist, nothing is written out.
I don't quite know what options you have then. In the case of
ProxyNodes and PagedLOD nodes, you might have to force reading of the
whole file before you can write it out again anyways... But that may
exceed the memory in your system (the reason why you use those nodes
in the first place, most of the time...).
You could catch that error, read the file yourself (original ive
extension), write it out to eive, and then re-write the parent file.
(recursively) That's so ugly I'm almost ashamed I thought of it...
I still don't get why Robert tells you it should work fine, and you
say it doesn't. Sure, there are any number of things that may go
wrong, but it should be easier than that.
Sorry I can't help more,
J-S
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Re: [osg-users] How do I Subclass a file loader?
Hi Brett,
As expected, the visitor goes and changes the names of all the
referenced files. Then the top level file is written out. The proxy
nodes try to write themselves out but since the files they reference
("referencedFile.eive") doesn't exist, nothing is written out.
I don't quite know what options you have then. In the case of ProxyNodes
and PagedLOD nodes, you might have to force reading of the whole file
before you can write it out again anyways... But that may exceed the
memory in your system (the reason why you use those nodes in the first
place, most of the time...).
You could catch that error, read the file yourself (original ive
extension), write it out to eive, and then re-write the parent file.
(recursively) That's so ugly I'm almost ashamed I thought of it...
I still don't get why Robert tells you it should work fine, and you say
it doesn't. Sure, there are any number of things that may go wrong, but
it should be easier than that.
Sorry I can't help more,
J-S
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Re: [osg-users] How do I Subclass a file loader?
Jean,
I did try my original solution which is how I know it writes out .ive
files. I also just implemented the visitor solution to see what happens.
As expected, the visitor goes and changes the names of all the
referenced files. Then the top level file is written out. The proxy
nodes try to write themselves out but since the files they reference
("referencedFile.eive") doesn't exist, nothing is written out.
I would need to be able to change the proxy node ReadWrite class which
is the part of the IVE loader that says to write out proxy nodes as
"ive" files. This would require me to derive from ReaderWriterIVE and
subclass the ProxyNode class so it writes out an "enc" file instead of
an "ive" file.
Thanks,
-Brett
Jean-Sébastien Guay wrote:
Hi Brett,
I'm wondering, if you suspect that ProxyNodes (and thus PagedLOD nodes
as well) would be a problem, why don't you just run a visitor that
would find those, and change their extension to eive (or whatever you
want)? Then if you write the top-level file, it will write the
referenced files with the right writer, and they will be re-read
correctly as well...
Or, try it without and see what happens. If what you suspect turns out
to be true, then you have a possible solution above, but if it all
works like magic you won't have wasted any time.
Hope this helps,
J-S
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Re: [osg-users] How do I Subclass a file loader?
Hi Brett, I'm wondering, if you suspect that ProxyNodes (and thus PagedLOD nodes as well) would be a problem, why don't you just run a visitor that would find those, and change their extension to eive (or whatever you want)? Then if you write the top-level file, it will write the referenced files with the right writer, and they will be re-read correctly as well... Or, try it without and see what happens. If what you suspect turns out to be true, then you have a possible solution above, but if it all works like magic you won't have wasted any time. Hope this helps, J-S -- __ Jean-Sebastien Guay[EMAIL PROTECTED] http://www.cm-labs.com/ http://whitestar02.webhop.org/ ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] How do I Subclass a file loader?
Robert,
Maybe some code will help Let's say I write my own ReaderWriter that
reads and writes encrypted ive files or "eive" files.
class ReaderWriterEive : public osgDB::ReaderWriter
{
public
virtual bool acceptsExtension(const std::string& extension) const
{
// Accepts "eive" as an extension.
}
// This takes in a .eive file which is an "encrypted ive file".
virtual osgDB::ReaderWriter::ReadResult readNode(const std::string&
file,
const osgDB::ReaderWriter::Options* options) const
{
// basic file checking, etc.
std::ifstream istream(file.c_str(), std::ios::in | std::ios::binary);
return readNode(istream, options);
}
virtual osgDB::ReaderWriter::ReadResult readNode(std::istream&
encryptedInput,
const osgDB::ReaderWriter::Options* options) const
{
ReadResult rr;
//
// 1. decrypt stream.
// 2. call the ive readerWriter's readNode() method on the
decrypted stream.
//
// Create an input stream to store the decrypted data in so the
reader can read it.
std::istringstream decryptedInputStream(std::ios::in |
std::ios::binary);
// Decrypted the encryptedInput into the decryptedInputStream.
if(decrypt(encryptedInput, decryptedInputStream))
{
// Find the correct reader writer.
osgDB::ReaderWriter* readerWriter =
osgDB::Registry::instance()->getReaderWriterForExtension(".ive");
if(readerWriter)
{
// Use the reader to read the decrypted data.
rr = readerWriter->readNode(decryptedInputStream,
options);
}
}
return rr;
}
virtual osgDB::ReaderWriter::WriteResult writeNode(const osg::Node& node,
const std::string& fileName, const osgDB::ReaderWriter::Options*
options) const
{
// basic file checking...
std::ofstream fout(fileName.c_str(), std::ios::out |
std::ios::binary);
if(!fout)
{
return osgDB::ReaderWriter::WriteResult::ERROR_IN_WRITING_FILE;
}
osgDB::ReaderWriter::WriteResult result = writeNode(node, fout,
local_opt.get());
fout.close();
return result;
}
virtual osgDB::ReaderWriter::WriteResult writeNode(const osg::Node& node,
std::ostream& fout, const osgDB::ReaderWriter::Options* options) const
{
WriteResult wr;
//
// 1. call the ive readerWriter's writeNode() method on the stream.
// 2. encrypt stream.
//
// Find the correct reader writer.
osgDB::ReaderWriter* readerWriter =
osgDB::Registry::instance()->getReaderWriterForExtension(".ive");
if(readerWriter)
{
// Create an output stream to store the raw ive data.
std::ostringstream rawIveData(std::ios::out |std::ios::binary);
// Use the reader to write the decrypted data.
// This is where the problem is. The ive's reader writer will
get called
// for every proxy node. My reader writer will not get called
and therefore all
// referenced files will be written out as unencrypted ive files.
wr = readerWriter->writeNode(node, rawIveData, options);
// Encrypt the decrypted data into the file output.
encrypt(rawIveData, fileOutputStream);
}
return wr;
}
The problem is in the writeNode() method that writes out to an ofstream.
When I give it a stream to write the data to, it does so, but it also
writes out all referenced files on its own, as regular .ive's. Perhaps
my design is flawed and there is a better way but I'm not seeing it in
the curl or osga loader.
Thanks,
Brett
Robert Osfield wrote:
HI Brett,
Please follow the suggestions already made. The osga plugin already
implementents a custom std::streambuf, and the curl plugin uses a
stingstream to adapt an external stream into something that the other
OSG plugins can use.
Robert.
On Thu, Oct 2, 2008 at 3:47 PM, brettwiesner <[EMAIL PROTECTED]> wrote:
Robert,
OK, I'm reading up on basic_streambuf now. In the meantime, maybe you
can help me understand how I can use a derived streambuf with the existing
IVE loader. Aren't I going to run into the same problem? When the IVE loader
comes across a proxy node, it will write out the node using the IVE loader
and it won't matter that I originally made the call to writeNode() with my
specialized ostream. It's going to create a file stream and write out the
proxy node and there's no way for me to change that.
Thanks,
Brett
Robert Osfield wrote:
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 OS
Re: [osg-users] How do I Subclass a file loader?
HI Brett, Please follow the suggestions already made. The osga plugin already implementents a custom std::streambuf, and the curl plugin uses a stingstream to adapt an external stream into something that the other OSG plugins can use. Robert. On Thu, Oct 2, 2008 at 3:47 PM, brettwiesner <[EMAIL PROTECTED]> wrote: > Robert, > > OK, I'm reading up on basic_streambuf now. In the meantime, maybe you > can help me understand how I can use a derived streambuf with the existing > IVE loader. Aren't I going to run into the same problem? When the IVE loader > comes across a proxy node, it will write out the node using the IVE loader > and it won't matter that I originally made the call to writeNode() with my > specialized ostream. It's going to create a file stream and write out the > proxy node and there's no way for me to change that. > > Thanks, > Brett > > Robert Osfield wrote: >> >> 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-
Re: [osg-users] How do I Subclass a file loader?
Robert, OK, I'm reading up on basic_streambuf now. In the meantime, maybe you can help me understand how I can use a derived streambuf with the existing IVE loader. Aren't I going to run into the same problem? When the IVE loader comes across a proxy node, it will write out the node using the IVE loader and it won't matter that I originally made the call to writeNode() with my specialized ostream. It's going to create a file stream and write out the proxy node and there's no way for me to change that. Thanks, Brett Robert Osfield wrote: 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 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] How do I Subclass a file loader?
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
Re: [osg-users] How do I Subclass a file loader?
brettwiesner wrote on Wednesday, October 01, 2008 3:27 PM: > 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. I think Robert was suggesting implementing your own istream/ostream that does the encryption internally, then passing that to the read/write methods that take streams. > 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? -- Bryan Thrall FlightSafety International [EMAIL PROTECTED] ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] How do I Subclass a file loader?
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
Re: [osg-users] How do I Subclass a file loader?
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
Re: [osg-users] How do I Subclass a file loader?
brettwiesner wrote on Wednesday, October 01, 2008 11:54 AM: > Bryan, > > Thanks for the reply. See inline... >> You could implement your own loader with a different file extension >> (say, ".enc") that does the en/decryption and then calls the IVE loader >> to load the resulting data. The curl loader does something like this. >> > > This is what I did originally. There was a problem with referenced > files; those wouldn't get encrypted/ decrypted. The IVE loader would > just process them as .ive's. > >> Or you could use a osgDB::Registry::Read/WriteFileCallback to de/encrypt >> the data before it gets read/sent from/to disk. >> >> > > That is interesting. I didn't know about those before. I think they will > have the same problem though. If I write a callback that does something > special when it's suppose to write out an encrypted file, and it uses > the IVE loader to get the data to encrypt, that process will still cause > the IVE loader to write out referenced files as .ive's. > > This would be pretty easy if I could derive from ReaderWriterIVE. It sounds like the problem is the referenced filenames; perhaps a visitor to change them to have the ".enc" extension so they get written through your loader rather than the IVE one directly? For example, a ProxyNode or PagedLOD that refers to "foo.osg" would have to be changed to refer to "foo.osg.enc" before you do the actual write. -- Bryan Thrall FlightSafety International [EMAIL PROTECTED] ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] How do I Subclass a file loader?
Bryan, Thanks for the reply. See inline... You could implement your own loader with a different file extension (say, ".enc") that does the en/decryption and then calls the IVE loader to load the resulting data. The curl loader does something like this. This is what I did originally. There was a problem with referenced files; those wouldn't get encrypted/ decrypted. The IVE loader would just process them as .ive's. Or you could use a osgDB::Registry::Read/WriteFileCallback to de/encrypt the data before it gets read/sent from/to disk. That is interesting. I didn't know about those before. I think they will have the same problem though. If I write a callback that does something special when it's suppose to write out an encrypted file, and it uses the IVE loader to get the data to encrypt, that process will still cause the IVE loader to write out referenced files as .ive's. This would be pretty easy if I could derive from ReaderWriterIVE. Thanks, Brett ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] How do I Subclass a file loader?
brettwiesner wrote on Wednesday, October 01, 2008 11:02 AM: > 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. > 2) Is there some other mechanism in OSG that will let me do this? You could implement your own loader with a different file extension (say, ".enc") that does the en/decryption and then calls the IVE loader to load the resulting data. The curl loader does something like this. Or you could use a osgDB::Registry::Read/WriteFileCallback to de/encrypt the data before it gets read/sent from/to disk. -- Bryan Thrall FlightSafety International [EMAIL PROTECTED] ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
[osg-users] How do I Subclass a file loader?
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
