Added CullVisitor::Identifier to help with cull operations that require a consistent identifier for

cull traveresals when osgViewer::Renderer uses double buffering.

include/osgUtil/CullVisitor

@@ -70,9 +70,19 @@ class OSGUTIL_EXPORT CullVisitor : public osg::NodeVisitor, public osg::CullStac
 
         virtual void reset();
 
+        struct Identifier : public osg::Referenced
+        {
+            Identifier() {}
+            virtual ~Identifier() {}
+        };
+
+        void setIdentifier(Identifier* identifier) { _identifier = identifier; }
+        Identifier* getIdentifier() { return _identifier.get(); }
+        const Identifier* getIdentifier() const { return _identifier.get(); }
+
         virtual osg::Vec3 getEyePoint() const { return getEyeLocal(); }
         virtual osg::Vec3 getViewPoint() const { return getViewPointLocal(); }
-        
+
         virtual float getDistanceToEyePoint(const osg::Vec3& pos, bool withLODScale) const;
         virtual float getDistanceFromEyePoint(const osg::Vec3& pos, bool withLODScale) const;
 
@@ -369,7 +379,8 @@ class OSGUTIL_EXPORT CullVisitor : public osg::NodeVisitor, public osg::CullStac
         
         typedef std::multimap<value_type, MatrixPlanesDrawables>   DistanceMatrixDrawableMap;
         DistanceMatrixDrawableMap                                  _nearPlaneCandidateMap;
-    
+
+        osg::ref_ptr<Identifier> _identifier;
 };
 
 inline void CullVisitor::addDrawable(osg::Drawable* drawable,osg::RefMatrix* matrix)

src/osgUtil/CullVisitor.cpp

@@ -53,6 +53,7 @@ CullVisitor::CullVisitor():
     _currentReuseRenderLeafIndex(0),
     _numberOfEncloseOverrideRenderBinDetails(0)
 {
+    _identifier = new Identifier;
 }
 
 CullVisitor::CullVisitor(const CullVisitor& rhs):
@@ -63,7 +64,8 @@ CullVisitor::CullVisitor(const CullVisitor& rhs):
     _computed_znear(FLT_MAX),
     _computed_zfar(-FLT_MAX),
     _currentReuseRenderLeafIndex(0),
-    _numberOfEncloseOverrideRenderBinDetails(0)
+    _numberOfEncloseOverrideRenderBinDetails(0),
+    _identifier(rhs._identifier)
 {
 }