From Sondra Iversion "Loading a single model from an externally

referenced file is a standard option for OpenFlight and is specified by
including the modelname in angle brackets, such as:  filename<modelname>.

The attached code identifies and handles this case."

VisualStudio/osgPlugins/flt/flt.dsp

@@ -131,6 +131,10 @@ SOURCE=..\..\..\src\osgPlugins\flt\FaceRecord.cpp
 # End Source File
 # Begin Source File
 
+SOURCE=..\..\..\src\osgPlugins\flt\FindExternalModelVisitor.cpp
+# End Source File
+# Begin Source File
+
 SOURCE=..\..\..\src\osgPlugins\flt\flt.cpp
 # End Source File
 # Begin Source File
@@ -323,6 +327,10 @@ SOURCE=..\..\..\src\osgPlugins\flt\FaceRecord.h
 # End Source File
 # Begin Source File
 
+SOURCE=..\..\..\src\osgPlugins\flt\FindExternalModelVisitor.h
+# End Source File
+# Begin Source File
+
 SOURCE=..\..\..\src\osgPlugins\flt\flt.h
 # End Source File
 # Begin Source File

src/osgPlugins/flt/ExternalRecord.cpp

@@ -25,6 +25,65 @@ ExternalRecord::~ExternalRecord()
 {
 }
 
+/**
+ * Return the filename of the external record.  External references are
+ * specified as either:
+ *    filename              - include the entire file
+ *    filename<modelname>   - include only the specified model from the file
+ *
+ * Therefore, the filename is either the entire string or the portion of the
+ * string prior to the first '<' character.
+ **/
+const std::string ExternalRecord::getFilename( void ) 
+{ 
+  std::string wholeFilename(getData()->szPath);
+  std::string filename;
+
+  size_t pos = wholeFilename.find_first_of( "<" );
+
+  if (pos != std::string::npos)
+  {
+    filename = wholeFilename.substr( 0, pos );
+  }
+  else
+  {
+    filename = wholeFilename;
+  }
+
+  return filename;
+}
+
+
+
+/**
+ * Return the modelname of the external record.  External references are
+ * specified as either:
+ *    filename              - include the entire file
+ *    filename<modelname>   - include only the specified model from the file
+ *
+ * Therefore, the modelname is the portion of the string between '<' and '>'
+ * characters when those characters are present.  Otherwise there is no
+ * modelname.
+ **/
+std::string ExternalRecord::getModelName( void ) 
+{ 
+  std::string wholeFilename(getData()->szPath);
+  std::string modelName;
+
+  size_t pos = wholeFilename.find_first_of( "<" );
+
+  if (pos != std::string::npos)
+  {
+    size_t pos2 = wholeFilename.find_first_of( ">" );
+
+    // Starting after the first '<', return the characters prior to the 
+    // first '>'.
+    modelName = wholeFilename.substr( pos+1, pos2-pos-1 );
+  }
+
+  return modelName;
+}
+
 
 void ExternalRecord::setExternal(FltFile* pExternal)
 {

src/osgPlugins/flt/ExternalRecord.h

@@ -45,8 +45,11 @@ class ExternalRecord : public PrimNodeRecord
         SExternalReference* getData() const { return (SExternalReference*)_pData; }
 
         void setExternal(FltFile* pExternal);
+
         FltFile* getExternal() { return _fltfile.get(); }
-        const std::string getFilename( void ) const { return std::string(getData()->szPath); }
+
+        const std::string getFilename( void );
+        std::string getModelName() ;
 
         enum Flag
         {

src/osgPlugins/flt/FindExternalModelVisitor.cpp

@@ -0,0 +1,18 @@
+// FindExternalModelVisitor.cpp
+
+#include "FindExternalModelVisitor.h"
+
+using namespace flt;
+
+
+/**
+ *
+ */
+void FindExternalModelVisitor::apply( osg::Node &node )
+{
+  if ( node.getName() == _modelName )
+    _model = &node;   // Store the node.  No need to process children.
+  else
+	  traverse( node );
+}
+

src/osgPlugins/flt/FindExternalModelVisitor.h

@@ -0,0 +1,36 @@
+// FindExternalModelVisitor.h
+
+#ifndef __FIND_EXTERNAL_MODEL_VISITOR_H_
+#define __FIND_EXTERNAL_MODEL_VISITOR_H_
+
+#include <iostream>
+#include <osg/Node>
+#include <osg/NodeVisitor>
+
+namespace flt {
+
+/**
+ * A visitor to find a named node.
+ */
+class FindExternalModelVisitor : public osg::NodeVisitor
+{
+public:
+	FindExternalModelVisitor( ) : osg::NodeVisitor( TRAVERSE_ALL_CHILDREN ) {}
+
+	virtual void apply( osg::Node &node );
+
+	void setModelName( std::string modelName ) { _modelName = modelName; }
+
+  osg::Node *getModel() { return _model.get(); }
+
+private:
+
+  std::string              _modelName;
+  osg::ref_ptr<osg::Node>  _model;
+
+};
+
+}; // end namespace flt
+
+#endif // __FIND_EXTERNAL_MODEL_VISITOR_H_
+

src/osgPlugins/flt/FltFile.cpp

@@ -209,7 +209,7 @@ bool FltFile::readFile(const std::string& fileName)
                     MaterialPool*   pMaterialPool = NULL;
                     LtPtAppearancePool* pLtPtAppearancePool = NULL;
                     LtPtAnimationPool* pLtPtAnimationPool = NULL;
-                    std::string filename(pSExternal->szPath);
+                    std::string filename( rec.getFilename() );
 
                     osg::notify(osg::INFO) << "External=" << filename << std::endl;
 

src/osgPlugins/flt/GNUmakefile

@@ -48,6 +48,7 @@ CXXFILES =\
     MultiTextureRecord.cpp\
     UVListRecord.cpp\
     BSPRecord.cpp\
+    FindExternalModelVisitor.cpp\
 #    PointLight.cpp\
 
 

src/osgPlugins/flt/flt2osg.cpp

@@ -84,6 +84,7 @@
 #include "LightSourcePaletteRecord.h"
 #include "AttrData.h"
 #include "BSPRecord.h"
+#include "FindExternalModelVisitor.h"
 
 static int dprint = 0 ;
 #define DPRINT if(dprint)fprintf
@@ -2448,7 +2449,47 @@ osg::Group* ConvertFromFLT::visitExternal(osg::Group& osgParent, ExternalRecord*
         pFile->setDesiredUnits( rec->getFltFile()->getDesiredUnits() );
         external = pFile->convert();
         if (external)
-            visitAncillary(osgParent, *external, rec)->addChild(external);
+        {
+          osg::Group *tempParent = visitAncillary(osgParent, *external, rec);
+
+          // In the situation in which only one model is required from an
+          // externally referenced file, it would be more efficient to only
+          // convert that one model from the FltFile records.  (This would be
+          // the preferred method if this loader is rewritten.)  However, 
+          // since this situation is fairly rare and it is currently much 
+          // more straight forward to work with the OSG structure, we will 
+          // just pull out the part of the OSG tree that is needed at this 
+          // point.
+
+          // If a model name was specified, find and add the node with
+          // that name.  Otherwise, add the entire tree.
+
+          std::string modelName = rec->getModelName();
+          if ( modelName.empty() )
+          {
+            // Add the entire externally referenced file
+            tempParent->addChild(external);
+          }
+          else
+          {
+            // Find the specified model
+            FindExternalModelVisitor findExternalModelVisitor;
+            findExternalModelVisitor.setModelName( modelName );
+            external->accept( findExternalModelVisitor );
+            osg::Node *model = findExternalModelVisitor.getModel();
+            if (model)
+            {
+              tempParent->addChild(model);
+            }
+            else
+            {
+              osg::notify(osg::WARN) << "In ConvertFromFLT::visitExternal,"
+                        << " the requested model " << modelName 
+                        << " was not found in external file " 
+                        << rec->getFilename() << std::endl;
+            }
+          }
+        }
     }
 
     return external;