From d9c1f4523121d476044053a8a44e7a783ee21cb8 Mon Sep 17 00:00:00 2001
From: Robert Osfield <robert@openscenegraph.com>
Date: Fri, 20 Nov 2009 14:39:15 +0000
Subject: [PATCH] From Wang Rui, "I've made a small fix to osgViewer/Scene.cpp,
 which is already attached. I would like to explain what I've done and why.

In Scene::updateSceneGraph(), change:

if (getSceneData())
{
        updateVisitor.setImageRequestHandler(getImagePager());
        getSceneData()->accept(updateVisitor);
}
if (getDatabasePager())
{
        // synchronize changes required by the DatabasePager thread to the scene graph
        getDatabasePager()->updateSceneGraph((*updateVisitor.getFrameStamp()));
}

to

if (getDatabasePager())
{
        // synchronize changes required by the DatabasePager thread to the scene graph
        getDatabasePager()->updateSceneGraph((*updateVisitor.getFrameStamp()));
}
if (getSceneData())
{
        updateVisitor.setImageRequestHandler(getImagePager());
        getSceneData()->accept(updateVisitor);
}

That is, just swap the positions of two 'if () {...}' segments.

While working on a paged terrain, I need to collect every newly allocated PagedLODs and make them temporarily unrenderable in the next frame, which are all done in a update callback. But I found that these PagedLODs will always be shown before collecting them, because of the unsuitable sequence in Scene::updateSceneGraph(). DatabasePager is synchronized AFTER the user updating traversal, that is, user cannot IMMEDIATELY find out changes made by DatabasePager.
 "
---
 src/osgViewer/Scene.cpp | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/src/osgViewer/Scene.cpp b/src/osgViewer/Scene.cpp
index d5ed8f6ce..6455f00d2 100644
--- a/src/osgViewer/Scene.cpp
+++ b/src/osgViewer/Scene.cpp
@@ -81,25 +81,24 @@ void Scene::updateSceneGraph(osg::NodeVisitor& updateVisitor)
 {
     if (!_sceneData) return;
 
-    if (getSceneData())
-    {
-        updateVisitor.setImageRequestHandler(getImagePager());
-        getSceneData()->accept(updateVisitor);
-    }
-
     if (getDatabasePager())
     {
         // synchronize changes required by the DatabasePager thread to the scene graph
         getDatabasePager()->updateSceneGraph((*updateVisitor.getFrameStamp()));
     }
 
+    if (getSceneData())
+    {
+        updateVisitor.setImageRequestHandler(getImagePager());
+        getSceneData()->accept(updateVisitor);
+    }
+
     if (getImagePager())
     {
         // synchronize changes required by the DatabasePager thread to the scene graph
         getImagePager()->updateSceneGraph(*(updateVisitor.getFrameStamp()));
     }
 
-
 }