From 25a6a67508f777d326fcfab105f8509cbb62cda9 Mon Sep 17 00:00:00 2001
From: scrawl <720642+scrawl@users.noreply.github.com>
Date: Mon, 29 Jan 2018 19:44:12 +0000
Subject: [PATCH] Fix the optimizer messing up LOD node's children (Fixes
 #4301)

---
 components/sceneutil/optimizer.cpp | 13 +++++++++++++
 components/sceneutil/optimizer.hpp |  2 ++
 2 files changed, 15 insertions(+)

diff --git a/components/sceneutil/optimizer.cpp b/components/sceneutil/optimizer.cpp
index e7d5b3a40..b86744599 100644
--- a/components/sceneutil/optimizer.cpp
+++ b/components/sceneutil/optimizer.cpp
@@ -800,6 +800,13 @@ bool Optimizer::RemoveRedundantNodesVisitor::isOperationPermissible(osg::Node& n
            isOperationPermissibleForObject(&node);
 }
 
+void Optimizer::RemoveRedundantNodesVisitor::apply(osg::LOD& lod)
+{
+    // don't remove any direct children of the LOD because they are used to define each LOD level.
+    for (unsigned int i=0; i<lod.getNumChildren(); ++i)
+        traverse(*lod.getChild(i));
+}
+
 void Optimizer::RemoveRedundantNodesVisitor::apply(osg::Group& group)
 {
     if (typeid(group)==typeid(osg::Group) &&
@@ -1849,6 +1856,12 @@ bool Optimizer::MergeGroupsVisitor::isOperationPermissible(osg::Group& node)
             isOperationPermissibleForObject(&node);
 }
 
+void Optimizer::MergeGroupsVisitor::apply(osg::LOD &lod)
+{
+    // don't merge the direct children of the LOD because they are used to define each LOD level.
+    traverse(lod);
+}
+
 void Optimizer::MergeGroupsVisitor::apply(osg::Group &group)
 {
     if (group.getNumChildren() <= 1)
diff --git a/components/sceneutil/optimizer.hpp b/components/sceneutil/optimizer.hpp
index 804938074..1e4ffb342 100644
--- a/components/sceneutil/optimizer.hpp
+++ b/components/sceneutil/optimizer.hpp
@@ -339,6 +339,7 @@ class Optimizer
 
                 virtual void apply(osg::Group& group);
                 virtual void apply(osg::Transform& transform);
+                virtual void apply(osg::LOD& lod);
 
                 bool isOperationPermissible(osg::Node& node);
 
@@ -358,6 +359,7 @@ class Optimizer
             bool isOperationPermissible(osg::Group& node);
 
             virtual void apply(osg::Group& group);
+            virtual void apply(osg::LOD& lod);
         };
 
         class MergeGeometryVisitor : public BaseOptimizerVisitor