From Mike Weiblen, with mods of using references by Robert Osfield for efficiency. Submission notes from Mike:

"By repurpose, I'm creating a new plugin that uses much of the .osg fileformat,
but with some changes.  Specifically, I'm creating a ".osgfs" plugin, which
represents the scenegraph hierarchy as a filesystem of nested subdirectories and
individual files for each node, rather than nested braces with everything in a
single monolithic file.  I intend to incorporate file alteration monitor events
to watch the filesystem for modifications and automatically reload.

The problem I'm running into is osgDB is too tightly coupled to the .osg format.
osgDB::Output::writeObject() contains literal .osg format-specific strings like
"{" to represent the Object hierarchy at too low a semantic level.  I propose
using virtual methods; my plugin can then derive from osgDB::Output and
represent Object hiearchy differently.
"

include/osgDB/Output

@@ -62,7 +62,10 @@ class OSGDB_EXPORT Output : public std::ofstream
         void moveOut();
         
         virtual bool writeObject(const osg::Object& obj);
-        
+        virtual void writeBeginObject(const std::string& name);
+        virtual void writeEndObject();
+        virtual void writeUseID(const std::string& id);
+        virtual void writeUniqueID(const std::string& id);
 
         bool getUniqueIDForObject(const osg::Object* obj,std::string& uniqueID);
         bool createUniqueIDForObject(const osg::Object* obj,std::string& uniqueID);

src/osgDB/Output.cpp

@@ -108,6 +108,27 @@ bool Output::writeObject(const osg::Object& obj)
     return Registry::instance()->writeObject(obj,*this);
 }
 
+
+void Output::writeBeginObject(const std::string& name)
+{
+    indent() << name << " {" << std::endl;
+}
+
+void Output::writeEndObject()
+{
+    indent() << "}" << std::endl;
+}
+
+void Output::writeUseID(const std::string& id)
+{
+    indent() << "Use " << id << std::endl;
+}
+
+void Output::writeUniqueID(const std::string& id)
+{
+    indent() << "UniqueID " << id << std::endl;
+}
+
 bool Output::getUniqueIDForObject(const osg::Object* obj,std::string& uniqueID)
 {
     UniqueIDToLabelMapping::iterator fitr = _objectToUniqueIDMap.find(obj);

src/osgDB/Registry.cpp

@@ -1116,14 +1116,14 @@ bool Registry::writeObject(const osg::Object& obj,Output& fw)
         std::string uniqueID;
         if (fw.getUniqueIDForObject(&obj,uniqueID))
         {
-            fw.indent() << "Use " << uniqueID << std::endl;
+            fw.writeUseID( uniqueID );
             return true;
         }
     }
 
-    std::string classname = obj.className();
-    std::string libraryName = obj.libraryName();
-    std::string compositeName = libraryName + "::" + classname;
+    const std::string classname( obj.className() );
+    const std::string libraryName( obj.libraryName() );
+    const std::string compositeName( libraryName + "::" + classname );
 
     // try composite name first
     DotOsgWrapperMap::iterator itr = _classNameWrapperMap.find(compositeName);
@@ -1131,11 +1131,11 @@ bool Registry::writeObject(const osg::Object& obj,Output& fw)
     if (itr==_classNameWrapperMap.end())
     {
         // first try the standard nodekit library.
-        std::string nodeKitLibraryName = createLibraryNameForNodeKit(obj.libraryName());
+        std::string nodeKitLibraryName = createLibraryNameForNodeKit(libraryName);
         if (loadLibrary(nodeKitLibraryName)) return writeObject(obj,fw);
 
         // otherwise try the osgdb_ plugin library.
-        std::string pluginLibraryName = createLibraryNameForExtension(obj.libraryName());
+        std::string pluginLibraryName = createLibraryNameForExtension(libraryName);
         if (loadLibrary(pluginLibraryName)) return writeObject(obj,fw);
 
         // otherwise try simple class name
@@ -1148,11 +1148,10 @@ bool Registry::writeObject(const osg::Object& obj,Output& fw)
         DotOsgWrapper* wrapper = itr->second.get();
         const DotOsgWrapper::Associates& assoc = wrapper->getAssociates();
 
-        if (strcmp(obj.libraryName(),"osg")==0)
+        if (libraryName=="osg")
         {
             // member of the core osg, so no need to have composite library::class name.
-            fw.indent() << wrapper->getName() << " {"<< std::endl;
-            fw.moveIn();
+            fw.writeBeginObject( wrapper->getName() );
         }
         else
         {
@@ -1160,15 +1159,14 @@ bool Registry::writeObject(const osg::Object& obj,Output& fw)
             std::string::size_type posDoubleColon = wrapper->getName().find("::");
             if (posDoubleColon != std::string::npos)
             {
-                fw.indent() << wrapper->getName() << " {"<< std::endl;
+                fw.writeBeginObject( wrapper->getName() );
             }
             else
             {
-                fw.indent() << obj.libraryName()<<"::"<< wrapper->getName() << " {"<< std::endl;
+                fw.writeBeginObject( libraryName + "::" + wrapper->getName() );
             }
-
-            fw.moveIn();
         }
+        fw.moveIn();
 
 
         // write out the unique ID if required.
@@ -1177,7 +1175,7 @@ bool Registry::writeObject(const osg::Object& obj,Output& fw)
             std::string uniqueID;
             fw.createUniqueIDForObject(&obj,uniqueID);
             fw.registerUniqueIDForObject(&obj,uniqueID);
-            fw.indent() << "UniqueID " << uniqueID << std::endl;
+            fw.writeUniqueID( uniqueID );
         }
 
         // read the local data by iterating through the associate
@@ -1231,7 +1229,7 @@ bool Registry::writeObject(const osg::Object& obj,Output& fw)
         }
 
         fw.moveOut();
-        fw.indent() << "}"<< std::endl;
+        fw.writeEndObject();
 
         return true;
     }