Store preloaded terrain view in the main thread

apps/openmw/mwworld/cellpreloader.cpp

@@ -167,6 +167,44 @@ namespace MWWorld
         std::vector<osg::ref_ptr<const osg::Object> > mPreloadedObjects;
     };
 
+    class TerrainPreloadItem : public SceneUtil::WorkItem
+    {
+    public:
+        TerrainPreloadItem(const std::vector<osg::ref_ptr<Terrain::View> >& views, Terrain::World* world, const std::vector<osg::Vec3f>& preloadPositions)
+            : mAbort(false)
+            , mTerrainViews(views)
+            , mWorld(world)
+            , mPreloadPositions(preloadPositions)
+        {
+        }
+
+        void storeViews(double referenceTime)
+        {
+            for (unsigned int i=0; i<mTerrainViews.size() && i<mPreloadPositions.size(); ++i)
+                mWorld->storeView(mTerrainViews[i], referenceTime);
+        }
+
+        virtual void doWork()
+        {
+            for (unsigned int i=0; i<mTerrainViews.size() && i<mPreloadPositions.size() && !mAbort; ++i)
+            {
+                mTerrainViews[i]->reset();
+                mWorld->preload(mTerrainViews[i], mPreloadPositions[i], mAbort);
+            }
+        }
+
+        virtual void abort()
+        {
+            mAbort = true;
+        }
+
+    private:
+        std::atomic<bool> mAbort;
+        std::vector<osg::ref_ptr<Terrain::View> > mTerrainViews;
+        Terrain::World* mWorld;
+        std::vector<osg::Vec3f> mPreloadPositions;
+    };
+
     /// Worker thread item: update the resource system's cache, effectively deleting unused entries.
     class UpdateCacheItem : public SceneUtil::WorkItem
     {
@@ -288,6 +326,9 @@ namespace MWWorld
             }
 
             mPreloadCells.erase(found);
+
+            if (cell->isExterior() && mTerrainPreloadItem && mTerrainPreloadItem->isDone())
+                mTerrainPreloadItem->storeViews(0.0);
         }
     }
 
@@ -329,6 +370,12 @@ namespace MWWorld
             mWorkQueue->addWorkItem(mUpdateCacheItem, true);
             mLastResourceCacheUpdate = timestamp;
         }
+
+        if (mTerrainPreloadItem && mTerrainPreloadItem->isDone())
+        {
+            mTerrainPreloadItem->storeViews(timestamp);
+            mTerrainPreloadItem = nullptr;
+        }
     }
 
     void CellPreloader::setExpiryDelay(double expiryDelay)
@@ -366,38 +413,6 @@ namespace MWWorld
         mUnrefQueue = unrefQueue;
     }
 
-    class TerrainPreloadItem : public SceneUtil::WorkItem
-    {
-    public:
-        TerrainPreloadItem(const std::vector<osg::ref_ptr<Terrain::View> >& views, Terrain::World* world, const std::vector<osg::Vec3f>& preloadPositions)
-            : mAbort(false)
-            , mTerrainViews(views)
-            , mWorld(world)
-            , mPreloadPositions(preloadPositions)
-        {
-        }
-
-        virtual void doWork()
-        {
-            for (unsigned int i=0; i<mTerrainViews.size() && i<mPreloadPositions.size() && !mAbort; ++i)
-            {
-                mWorld->preload(mTerrainViews[i], mPreloadPositions[i], mAbort);
-                mTerrainViews[i]->reset();
-            }
-        }
-
-        virtual void abort()
-        {
-            mAbort = true;
-        }
-
-    private:
-        std::atomic<bool> mAbort;
-        std::vector<osg::ref_ptr<Terrain::View> > mTerrainViews;
-        Terrain::World* mWorld;
-        std::vector<osg::Vec3f> mPreloadPositions;
-    };
-
     void CellPreloader::setTerrainPreloadPositions(const std::vector<osg::Vec3f> &positions)
     {
         if (mTerrainPreloadItem && !mTerrainPreloadItem->isDone())
@@ -418,8 +433,6 @@ namespace MWWorld
                     mTerrainViews.push_back(mTerrain->createView());
             }
 
-            // TODO: provide some way of giving the preloaded view to the main thread when we enter the cell
-            // right now, we just use it to make sure the resources are preloaded
             mTerrainPreloadPositions = positions;
             mTerrainPreloadItem = new TerrainPreloadItem(mTerrainViews, mTerrain, positions);
             mWorkQueue->addWorkItem(mTerrainPreloadItem);

apps/openmw/mwworld/cellpreloader.hpp

@@ -31,6 +31,7 @@ namespace MWRender
 namespace MWWorld
 {
     class CellStore;
+    class TerrainPreloadItem;
 
     class CellPreloader
     {
@@ -105,7 +106,7 @@ namespace MWWorld
 
         std::vector<osg::ref_ptr<Terrain::View> > mTerrainViews;
         std::vector<osg::Vec3f> mTerrainPreloadPositions;
-        osg::ref_ptr<SceneUtil::WorkItem> mTerrainPreloadItem;
+        osg::ref_ptr<TerrainPreloadItem> mTerrainPreloadItem;
         osg::ref_ptr<SceneUtil::WorkItem> mUpdateCacheItem;
     };
 

components/terrain/quadtreeworld.cpp

@@ -440,8 +440,14 @@ void QuadTreeWorld::accept(osg::NodeVisitor &nv)
     if (!isCullVisitor)
         vd->reset(); // we can't reuse intersection views in the next frame because they only contain what is touched by the intersection ray.
 
-    vd->finishFrame(nv.getTraversalNumber());
-    mRootNode->getViewDataMap()->clearUnusedViews(nv.getTraversalNumber());
+    vd->markUnchanged();
+
+    double referenceTime = nv.getFrameStamp() ? nv.getFrameStamp()->getReferenceTime() : 0.0;
+    if (referenceTime != 0.0)
+    {
+        vd->setLastUsageTimeStamp(referenceTime);
+        mViewDataMap->clearUnusedViews(referenceTime);
+    }
 }
 
 void QuadTreeWorld::ensureQuadTreeBuilt()
@@ -504,6 +510,17 @@ void QuadTreeWorld::preload(View *view, const osg::Vec3f &viewPoint, std::atomic
         ViewData::Entry& entry = vd->getEntry(i);
         loadRenderingNode(entry, vd, mVertexLodMod, mChunkManager.get());
     }
+    vd->markUnchanged();
+}
+
+void QuadTreeWorld::storeView(const View* view, double referenceTime)
+{
+    osg::ref_ptr<osg::Object> dummy = new osg::DummyObject;
+    const ViewData* vd = static_cast<const ViewData*>(view);
+    bool needsUpdate = false;
+    ViewData* stored = mViewDataMap->getViewData(dummy, vd->getViewPoint(), needsUpdate);
+    stored->copyFrom(*vd);
+    stored->setLastUsageTimeStamp(referenceTime);
 }
 
 void QuadTreeWorld::reportStats(unsigned int frameNumber, osg::Stats *stats)

components/terrain/quadtreeworld.hpp

@@ -37,8 +37,8 @@ namespace Terrain
         virtual void unloadCell(int x, int y);
 
         View* createView();
-
-        void preload(View* view, const osg::Vec3f& viewPoint, std::atomic<bool>& abort);
+        void preload(View* view, const osg::Vec3f& eyePoint, std::atomic<bool>& abort);
+        void storeView(const View* view, double referenceTime);
 
         void reportStats(unsigned int frameNumber, osg::Stats* stats);
 

components/terrain/viewdata.cpp

@@ -5,7 +5,7 @@ namespace Terrain
 
 ViewData::ViewData()
     : mNumEntries(0)
-    , mFrameLastUsed(0)
+    , mLastUsageTimeStamp(0.0)
     , mChanged(false)
     , mHasViewPoint(false)
 {
@@ -85,7 +85,7 @@ void ViewData::clear()
     for (unsigned int i=0; i<mEntries.size(); ++i)
         mEntries[i].set(nullptr, false);
     mNumEntries = 0;
-    mFrameLastUsed = 0;
+    mLastUsageTimeStamp = 0;
     mChanged = false;
     mHasViewPoint = false;
 }
@@ -173,12 +173,12 @@ ViewData *ViewDataMap::createOrReuseView()
     }
 }
 
-void ViewDataMap::clearUnusedViews(unsigned int frame)
+void ViewDataMap::clearUnusedViews(double referenceTime)
 {
     for (Map::iterator it = mViews.begin(); it != mViews.end(); )
     {
         ViewData* vd = it->second;
-        if (vd->getFrameLastUsed() + 2 < frame)
+        if (vd->getLastUsageTimeStamp() + mExpiryDelay < referenceTime)
         {
             vd->clear();
             mUnusedViews.push_back(vd);

components/terrain/viewdata.hpp

@@ -46,11 +46,12 @@ namespace Terrain
 
         Entry& getEntry(unsigned int i);
 
-        unsigned int getFrameLastUsed() const { return mFrameLastUsed; }
-        void finishFrame(unsigned int frame) { mFrameLastUsed = frame; mChanged = false; }
+        double getLastUsageTimeStamp() const { return mLastUsageTimeStamp; }
+        void setLastUsageTimeStamp(double timeStamp) { mLastUsageTimeStamp = timeStamp; }
 
         /// @return Have any nodes changed since the last frame
         bool hasChanged() const;
+        void markUnchanged() { mChanged = false; }
 
         bool hasViewPoint() const;
 
@@ -60,7 +61,7 @@ namespace Terrain
     private:
         std::vector<Entry> mEntries;
         unsigned int mNumEntries;
-        unsigned int mFrameLastUsed;
+        double mLastUsageTimeStamp;
         bool mChanged;
         osg::Vec3f mViewPoint;
         bool mHasViewPoint;
@@ -71,14 +72,16 @@ namespace Terrain
     {
     public:
         ViewDataMap()
-            : mReuseDistance(100) // large value should be safe because the visibility of each node is still updated individually for each camera even if the base view was reused.
+            : mReuseDistance(300) // large value should be safe because the visibility of each node is still updated individually for each camera even if the base view was reused.
+                                  // this value also serves as a threshold for when a newly loaded LOD gets unloaded again so that if you hover around an LOD transition point the LODs won't keep loading and unloading all the time.
+            , mExpiryDelay(1.f)
         {}
 
         ViewData* getViewData(osg::Object* viewer, const osg::Vec3f& viewPoint, bool& needsUpdate);
 
         ViewData* createOrReuseView();
 
-        void clearUnusedViews(unsigned int frame);
+        void clearUnusedViews(double referenceTime);
 
         void clear();
 
@@ -93,6 +96,7 @@ namespace Terrain
         Map mViews;
 
         float mReuseDistance;
+        float mExpiryDelay; // time in seconds for unused view to be removed
 
         std::deque<ViewData*> mUnusedViews;
 

components/terrain/world.hpp

@@ -82,7 +82,7 @@ namespace Terrain
         /// @note Thread safe.
         virtual void clearAssociatedCaches();
 
-        /// Load a terrain cell at maximum LOD and store it in the View for later use.
+        /// Load a terrain cell and store it in the View for later use.
         /// @note Thread safe.
         virtual void cacheCell(View* view, int x, int y) {}
 
@@ -106,6 +106,10 @@ namespace Terrain
 
         virtual void preload(View* view, const osg::Vec3f& viewPoint, std::atomic<bool>& abort) {}
 
+        /// Store a preloaded view into the cache with the intent that the next rendering traversal can use it.
+        /// @note Not thread safe.
+        virtual void storeView(const View* view, double referenceTime) {}
+
         virtual void reportStats(unsigned int frameNumber, osg::Stats* stats) {}
 
         /// Set the default viewer (usually a Camera), used as viewpoint for any viewers that don't use their own viewpoint.