From Paul Martz, Introduced osg::OcclusionQueryNode with support for OpenGL occlusion query extension

src/osgUtil/CullVisitor.cpp

@@ -19,6 +19,7 @@
 #include <osg/ClipNode>
 #include <osg/TexGenNode>
 #include <osg/OccluderNode>
+#include <osg/OcclusionQueryNode>
 #include <osg/Notify>
 #include <osg/TexEnv>
 #include <osg/AlphaFunc>
@@ -1392,5 +1393,34 @@ void CullVisitor::apply(osg::OccluderNode& node)
     popOccludersCurrentMask(_nodePath);
 }
 
+void CullVisitor::apply(osg::OcclusionQueryNode& node)
+{
+    if (isCulled(node)) return;
+
+    // push the culling mode.
+    pushCurrentMask();
+
+    // push the node's state.
+    StateSet* node_state = node.getStateSet();
+    if (node_state) pushStateSet(node_state);
 
 
+    osg::Camera* camera = getRenderStage()->getCamera();
+    // If previous query indicates visible, then traverse as usual.
+    if (node.getPassed( camera, getDistanceToEyePoint( node.getBound()._center, false ) ))
+        handle_cull_callbacks_and_traverse(node);
+
+    // Traverse the query subtree if OcclusionQueryNode needs to issue another query.
+    node.traverseQuery( camera, *this );
+
+    // Traverse the debug bounding geometry, if enabled.
+    node.traverseDebug( *this );
+
+
+    // pop the node's state off the render graph stack.    
+    if (node_state) popStateSet();
+
+    // pop the culling mode.
+    popCurrentMask();
+}
+