Index: OpenSceneGraph/trunk/src/osgPlugins/OpenFlight/Document.cpp
===================================================================
--- OpenSceneGraph/trunk/src/osgPlugins/OpenFlight/Document.cpp (revision 8563)
+++ OpenSceneGraph/trunk/src/osgPlugins/OpenFlight/Document.cpp (revision 10084)
@@ -46,4 +46,5 @@
     _shaderPoolParent(false)
 {
+    _subsurfaceDepth = new osg::Depth(osg::Depth::LESS, 0.0, 1.0,false);
 }
 
@@ -111,4 +112,20 @@
 }
 
+void Document::setSubSurfacePolygonOffset(int level, osg::PolygonOffset* po)
+{
+    _subsurfacePolygonOffsets[level] = po;
+}
+
+osg::PolygonOffset* Document::getSubSurfacePolygonOffset(int level)
+{
+    osg::notify(osg::DEBUG_INFO)<<"Document::getSubSurfacePolygonOffset("<<level<<")"<<std::endl;
+    osg::ref_ptr<osg::PolygonOffset>& po = _subsurfacePolygonOffsets[level];
+    if (!po)
+    {
+        po = new osg::PolygonOffset(-1.0f*float(level), -1.0f);
+    }
+    return po.get();
+}
+
 double flt::unitsToMeters(CoordUnits unit)
 {