From Ricard Schmidt, dot writer plugin.

src/osgPlugins/dot/ReaderWriterDOT.cpp

@@ -0,0 +1,41 @@
+/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2006 Robert Osfield 
+ *
+ * This library is open source and may be redistributed and/or modified under  
+ * the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or 
+ * (at your option) any later version.  The full license is in LICENSE file
+ * included with this distribution, and on the openscenegraph.org website.
+ * 
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
+ * OpenSceneGraph Public License for more details.
+*/
+#include <osgDB/ReaderWriter>
+#include <osgDB/FileUtils>
+#include <osgDB/FileNameUtils>
+#include "SimpleDotVisitor.h"
+
+class ReaderWriterDOT : public osgDB::ReaderWriter {
+  public:
+    virtual const char* className() const { return "DOT Writer"; }
+    virtual bool acceptsExtension(const std::string& extension) const { return osgDB::equalCaseInsensitive(extension,"dot"); }
+
+    virtual WriteResult writeNode(const osg::Node& node,const std::string& fileName,const Options* options = NULL) const { 
+      std::ofstream o( fileName.c_str(), std::ios_base::out );
+      if ( o ) {
+        return writeNode( node, o, options );
+      }
+
+      return WriteResult(WriteResult::ERROR_IN_WRITING_FILE);
+    }
+    
+    virtual WriteResult writeNode(const osg::Node& node,std::ostream& fout,const Options* options = NULL) const {
+      osgDot::SimpleDotVisitor sdv;
+      sdv.run( *const_cast<osg::Node*>( &node ), &fout );
+      return WriteResult(WriteResult::FILE_SAVED);
+    }
+};
+
+// now register with Registry to instantiate the above
+// reader/writer.
+REGISTER_OSGPLUGIN(dot, ReaderWriterDOT)