From 03b71d3c30a92f7bdf13212510ed591f80a73637 Mon Sep 17 00:00:00 2001
From: Andrei Kortunov <andrei.kortunov@yandex.ru>
Date: Sun, 27 Jan 2019 15:19:48 +0400
Subject: [PATCH] Improve switchable nodes handling by optimizer

---
 components/sceneutil/optimizer.cpp | 17 ++++++++++++++++-
 components/sceneutil/optimizer.hpp |  2 ++
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/components/sceneutil/optimizer.cpp b/components/sceneutil/optimizer.cpp
index f2717fea2..25ad03fba 100644
--- a/components/sceneutil/optimizer.cpp
+++ b/components/sceneutil/optimizer.cpp
@@ -737,6 +737,20 @@ bool Optimizer::CombineStaticTransformsVisitor::removeTransforms(osg::Node* node
 // RemoveEmptyNodes.
 ////////////////////////////////////////////////////////////////////////////
 
+void Optimizer::RemoveEmptyNodesVisitor::apply(osg::Switch& switchNode)
+{
+    // We should keep all switch child nodes since they reflect different switch states.
+    for (unsigned int i=0; i<switchNode.getNumChildren(); ++i)
+        traverse(*switchNode.getChild(i));
+}
+
+void Optimizer::RemoveEmptyNodesVisitor::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::RemoveEmptyNodesVisitor::apply(osg::Group& group)
 {
     if (group.getNumParents()>0)
@@ -1856,7 +1870,8 @@ bool Optimizer::MergeGeometryVisitor::mergePrimitive(osg::DrawElementsUInt& lhs,
 
 bool Optimizer::MergeGroupsVisitor::isOperationPermissible(osg::Group& node)
 {
-    return !node.asTransform() &&
+    return !node.asSwitch() &&
+           !node.asTransform() &&
            !node.getCullCallback() &&
            !node.getEventCallback() &&
            !node.getUpdateCallback() &&
diff --git a/components/sceneutil/optimizer.hpp b/components/sceneutil/optimizer.hpp
index 6dd4394d1..9974e7097 100644
--- a/components/sceneutil/optimizer.hpp
+++ b/components/sceneutil/optimizer.hpp
@@ -321,6 +321,8 @@ class Optimizer
                     BaseOptimizerVisitor(optimizer, REMOVE_REDUNDANT_NODES) {}
 
                 virtual void apply(osg::Group& group);
+                virtual void apply(osg::LOD& lod);
+                virtual void apply(osg::Switch& switchNode);
 
                 void removeEmptyNodes();