Hi J-S,
The dotosg wrapper / serializer recognizes classes from there class
names. These should be defined with the className() method (or
META_Node macro) and the writing processor in osgDB will try to find a
wrapper corresponding to the name. If found, the node will be written
to files; otherwise the unknown node and its subgraph will be skipped.
It can't decide if the OceanScene is derived from osg::Group without a
name-wrapper map recorded in the Registry object.
The ive plugin is not limited in this way, because it implements
read()/write() virtual functions for all common scene elements, but it
must have all the libraries as dependencies and is hard to extend.
Adding and implementing read()/write() virtual methods for all OSG
classes may be better for serialization IO, but it will certainly
cause changes to almost all source files and be completely a pain for
future debugging and compatibility tests.
Do you mind if I could have time to help finish the serializers of the
osgOcean project someday? :-)
Cheers,
Wang Rui
2010/12/1 Jean-Sébastien Guay <jean-sebastien.g...@cm-labs.com>:
> Hello all,
>
> I noticed when doing osgDB::writeNodeFile to .osg file with an
> osgOcean::OceanScene in the graph, the written graph stops at that node,
> i.e. that node and all its children (it is a subclass of osg::Group) are not
> in the file.
>
> I would think that even if no wrapper / serializer exists for this node
> type, it should be writable as its base class type (osg::Group)... Is this
> not what's supposed to happen?
>
> Initially, the OceanScene class didn't use the META_Node(library, class)
> macro, and I thought that was why it couldn't be saved even as its base
> class type (or any node type). But I changed the header to use the macro,
> and it still isn't written.
>
> I know the best thing would be to provide a serializer / osgdb_osgOcean
> plugin to be able to write and read the exact type and its members from .osg
> files (and other types). But what is the minimum I need to do so that at
> least, the writeNodeFile() traversal will traverse it as an osg::Group and
> write its children?
>
> Is there a way to write a callback that would be called for unknown node
> types, and from which I could static_cast<osg::Group*> and then traverse
> that, which would resolve the base class type correctly?
>
> I even checked the OceanScene::traverse() method, and it is written as:
>
> void OceanScene::traverse( osg::NodeVisitor& nv )
> {
> if( nv.getVisitorType() == osg::NodeVisitor::UPDATE_VISITOR )
> {
> //...
> }
> else if (nv.getVisitorType() == osg::NodeVisitor::CULL_VISITOR)
> {
> //...
> }
> else
> osg::Group::traverse(nv);
> }
>
> So I would have thought that would let the writeNodeFile() do its work as if
> it were an osg::Group...
>
> Thanks in advance,
>
> J-S
> --
> ______________________________________________________
> Jean-Sebastien Guay jean-sebastien.g...@cm-labs.com
> 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
>
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