Fix waiting on initial quad tree build

components/terrain/quadtreeworld.cpp

@@ -337,34 +337,39 @@ void QuadTreeWorld::accept(osg::NodeVisitor &nv)
     mRootNode->getViewDataMap()->clearUnusedViews(nv.getTraversalNumber());
 }
 
-void QuadTreeWorld::loadCell(int x, int y)
+void QuadTreeWorld::ensureQuadTreeBuilt()
 {
-    if (mQuadTreeBuilt && !mRootNode)
     {
+        OpenThreads::ScopedLock<OpenThreads::Mutex> lock(mQuadTreeMutex);
+        if (mQuadTreeBuilt)
+            return;
+        if (!mQuadTreeBuilt && !mWorkItem)
+        {
+            const float minSize = 1/4.f;
+            mWorkItem = new BuildQuadTreeItem(mStorage, mViewDataMap.get(), minSize);
+            mWorkQueue->addWorkItem(mWorkItem);
+        }
+    }
+
+    mWorkItem->waitTillDone();
+    {
+        OpenThreads::ScopedLock<OpenThreads::Mutex> lock(mQuadTreeMutex);
         mRootNode = mWorkItem->getRootNode();
         mRootNode->setWorld(this);
-        mTerrainRoot->addChild(mRootNode);
-        mWorkItem = NULL;
+        mQuadTreeBuilt = true;
     }
 }
 
-osg::ref_ptr<osg::Node> QuadTreeWorld::cacheCell(int x, int y)
+void QuadTreeWorld::enable(bool enabled)
 {
-    if (!mQuadTreeBuilt)
+    if (enabled)
     {
-        const float minSize = 1/4.f;
-        mWorkItem = new BuildQuadTreeItem(mStorage, mViewDataMap.get(), minSize);
-        mWorkQueue->addWorkItem(mWorkItem);
-
-        mWorkItem->waitTillDone();
+        ensureQuadTreeBuilt();
 
-        mQuadTreeBuilt = true;
+        if (!mRootNode->getNumParents())
+            mTerrainRoot->addChild(mRootNode);
     }
-    return NULL;
-}
 
-void QuadTreeWorld::enable(bool enabled)
-{
     if (mRootNode)
         mRootNode->setNodeMask(enabled ? ~0 : 0);
 }

components/terrain/quadtreeworld.hpp

@@ -5,6 +5,8 @@
 
 #include "world.hpp"
 
+#include <OpenThreads/Mutex>
+
 namespace SceneUtil
 {
     class WorkQueue;
@@ -30,12 +32,11 @@ namespace Terrain
 
         void accept(osg::NodeVisitor& nv);
 
-        virtual void loadCell(int x, int y);
-        virtual osg::ref_ptr<osg::Node> cacheCell(int x, int y);
-
         virtual void enable(bool enabled);
 
     private:
+        void ensureQuadTreeBuilt();
+
         osg::ref_ptr<RootNode> mRootNode;
 
         osg::ref_ptr<SceneUtil::WorkQueue> mWorkQueue;
@@ -44,6 +45,7 @@ namespace Terrain
 
         osg::ref_ptr<ViewDataMap> mViewDataMap;
 
+        OpenThreads::Mutex mQuadTreeMutex;
         bool mQuadTreeBuilt;
     };