Reuse traversal result for different traversal with same view point

Rename eyePoint to viewPoint to match OSG conventions (eyePoint is the camera position, viewPoint is for LOD handling)

apps/openmw/mwworld/cellpreloader.cpp

@@ -382,7 +382,7 @@ namespace MWWorld
             for (unsigned int i=0; i<mTerrainViews.size() && i<mPreloadPositions.size() && !mAbort; ++i)
             {
                 mWorld->preload(mTerrainViews[i], mPreloadPositions[i], mAbort);
-                mTerrainViews[i]->reset(0);
+                mTerrainViews[i]->reset();
             }
         }
 

components/terrain/quadtreenode.cpp

@@ -114,9 +114,10 @@ void QuadTreeNode::traverse(osg::NodeVisitor &nv)
     if (!hasValidBounds())
         return;
 
-    ViewData* vd = getView(nv);
+    bool needsUpdate = true;
+    ViewData* vd = getView(nv, needsUpdate);
 
-    if ((mLodCallback && mLodCallback->isSufficientDetail(this, distance(vd->getEyePoint()))) || !getNumChildren())
+    if ((mLodCallback && mLodCallback->isSufficientDetail(this, distance(vd->getViewPoint()))) || !getNumChildren())
         vd->add(this, true);
     else
         osg::Group::traverse(nv);
@@ -142,26 +143,24 @@ ViewDataMap *QuadTreeNode::getViewDataMap()
     return mViewDataMap;
 }
 
-ViewData* QuadTreeNode::getView(osg::NodeVisitor &nv)
+ViewData* QuadTreeNode::getView(osg::NodeVisitor &nv, bool& needsUpdate)
 {
+    ViewData* vd = NULL;
     if (nv.getVisitorType() == osg::NodeVisitor::CULL_VISITOR)
     {
         osgUtil::CullVisitor* cv = static_cast<osgUtil::CullVisitor*>(&nv);
-        ViewData* vd = mViewDataMap->getViewData(cv->getCurrentCamera());
-        vd->setEyePoint(nv.getViewPoint());
-        return vd;
+        vd = mViewDataMap->getViewData(cv->getCurrentCamera(), nv.getViewPoint(), needsUpdate);
     }
     else // INTERSECTION_VISITOR
     {
+        osg::Vec3f viewPoint = nv.getViewPoint();
+        mViewDataMap->getDefaultViewPoint(viewPoint);
+
         static osg::ref_ptr<osg::Object> dummyObj = new osg::DummyObject;
-        ViewData* vd = mViewDataMap->getViewData(dummyObj.get());
-        ViewData* defaultView = mViewDataMap->getDefaultView();
-        if (defaultView->hasEyePoint())
-            vd->setEyePoint(defaultView->getEyePoint());
-        else
-            vd->setEyePoint(nv.getEyePoint());
-        return vd;
+        vd = mViewDataMap->getViewData(dummyObj.get(), viewPoint, needsUpdate);
+        needsUpdate = true;
     }
+    return vd;
 }
 
 void QuadTreeNode::setBoundingBox(const osg::BoundingBox &boundingBox)

components/terrain/quadtreenode.hpp

@@ -85,7 +85,7 @@ namespace Terrain
         ViewDataMap* getViewDataMap();
 
         /// Create or retrieve a view for the given traversal.
-        ViewData* getView(osg::NodeVisitor& nv);
+        ViewData* getView(osg::NodeVisitor& nv, bool& needsUpdate);
 
     private:
         QuadTreeNode* mParent;

components/terrain/quadtreeworld.cpp

@@ -247,7 +247,7 @@ QuadTreeWorld::~QuadTreeWorld()
 }
 
 
-void traverse(QuadTreeNode* node, ViewData* vd, osg::NodeVisitor* nv, LodCallback* lodCallback, const osg::Vec3f& eyePoint, bool visible, float maxDist)
+void traverse(QuadTreeNode* node, ViewData* vd, osg::NodeVisitor* nv, LodCallback* lodCallback, const osg::Vec3f& viewPoint, bool visible, float maxDist)
 {
     if (!node->hasValidBounds())
         return;
@@ -255,7 +255,7 @@ void traverse(QuadTreeNode* node, ViewData* vd, osg::NodeVisitor* nv, LodCallbac
     if (nv && nv->getVisitorType() == osg::NodeVisitor::CULL_VISITOR)
         visible = visible && !static_cast<osgUtil::CullVisitor*>(nv)->isCulled(node->getBoundingBox());
 
-    float dist = node->distance(eyePoint);
+    float dist = node->distance(viewPoint);
     if (dist > maxDist)
         return;
 
@@ -266,7 +266,7 @@ void traverse(QuadTreeNode* node, ViewData* vd, osg::NodeVisitor* nv, LodCallbac
     else
     {
         for (unsigned int i=0; i<node->getNumChildren(); ++i)
-            traverse(node->getChild(i), vd, nv, lodCallback, eyePoint, visible, maxDist);
+            traverse(node->getChild(i), vd, nv, lodCallback, viewPoint, visible, maxDist);
     }
 }
 
@@ -367,7 +367,8 @@ void loadRenderingNode(ViewData::Entry& entry, ViewData* vd, int vertexLodMod, C
 
 void QuadTreeWorld::accept(osg::NodeVisitor &nv)
 {
-    if (nv.getVisitorType() != osg::NodeVisitor::CULL_VISITOR && nv.getVisitorType() != osg::NodeVisitor::INTERSECTION_VISITOR)
+    bool isCullVisitor = nv.getVisitorType() == osg::NodeVisitor::CULL_VISITOR;
+    if (!isCullVisitor && nv.getVisitorType() != osg::NodeVisitor::INTERSECTION_VISITOR)
     {
         if (nv.getName().find("AcceptedByComponentsTerrainQuadTreeWorld") != std::string::npos)
         {
@@ -382,26 +383,40 @@ void QuadTreeWorld::accept(osg::NodeVisitor &nv)
         return;
     }
 
-    ViewData* vd = mRootNode->getView(nv);
+    bool needsUpdate = false;
+    ViewData* vd = mRootNode->getView(nv, needsUpdate);
 
-    if (nv.getVisitorType() == osg::NodeVisitor::CULL_VISITOR)
+    if (needsUpdate)
     {
-        osgUtil::CullVisitor* cv = static_cast<osgUtil::CullVisitor*>(&nv);
-
-        osg::UserDataContainer* udc = cv->getCurrentCamera()->getUserDataContainer();
-        if (udc && udc->getNumDescriptions() >= 2 && udc->getDescriptions()[0] == "NoTerrainLod")
+        vd->reset();
+        if (isCullVisitor)
         {
-            std::istringstream stream(udc->getDescriptions()[1]);
-            int x,y;
-            stream >> x;
-            stream >> y;
-            traverseToCell(mRootNode.get(), vd, x,y);
+            osgUtil::CullVisitor* cv = static_cast<osgUtil::CullVisitor*>(&nv);
+
+            osg::UserDataContainer* udc = cv->getCurrentCamera()->getUserDataContainer();
+            if (udc && udc->getNumDescriptions() >= 2 && udc->getDescriptions()[0] == "NoTerrainLod")
+            {
+                std::istringstream stream(udc->getDescriptions()[1]);
+                int x,y;
+                stream >> x;
+                stream >> y;
+                traverseToCell(mRootNode.get(), vd, x,y);
+            }
+            else
+                traverse(mRootNode.get(), vd, cv, mRootNode->getLodCallback(), cv->getViewPoint(), true, mViewDistance);
         }
         else
-            traverse(mRootNode.get(), vd, cv, mRootNode->getLodCallback(), cv->getViewPoint(), true, mViewDistance);
+            mRootNode->traverse(nv);
+    }
+    else if (isCullVisitor)
+    {
+        // view point is the same, but must still update visible status in case the camera has rotated
+        for (unsigned int i=0; i<vd->getNumEntries(); ++i)
+        {
+            ViewData::Entry& entry = vd->getEntry(i);
+            entry.set(entry.mNode, !static_cast<osgUtil::CullVisitor*>(&nv)->isCulled(entry.mNode->getBoundingBox()));
+        }
     }
-    else
-        mRootNode->traverse(nv);
 
     for (unsigned int i=0; i<vd->getNumEntries(); ++i)
     {
@@ -416,13 +431,16 @@ void QuadTreeWorld::accept(osg::NodeVisitor &nv)
             {
                 mCompositeMapRenderer->setImmediate(static_cast<CompositeMap*>(udc->getUserData()));
                 udc->setUserData(nullptr);
+
             }
             entry.mRenderingNode->accept(nv);
         }
     }
 
-    vd->reset(nv.getTraversalNumber());
+    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());
 }
 
@@ -473,12 +491,13 @@ View* QuadTreeWorld::createView()
     return new ViewData;
 }
 
-void QuadTreeWorld::preload(View *view, const osg::Vec3f &eyePoint, std::atomic<bool> &abort)
+void QuadTreeWorld::preload(View *view, const osg::Vec3f &viewPoint, std::atomic<bool> &abort)
 {
     ensureQuadTreeBuilt();
 
     ViewData* vd = static_cast<ViewData*>(view);
-    traverse(mRootNode.get(), vd, nullptr, mRootNode->getLodCallback(), eyePoint, false, mViewDistance);
+    vd->setViewPoint(viewPoint);
+    traverse(mRootNode.get(), vd, nullptr, mRootNode->getLodCallback(), viewPoint, false, mViewDistance);
 
     for (unsigned int i=0; i<vd->getNumEntries() && !abort; ++i)
     {

components/terrain/quadtreeworld.hpp

@@ -37,7 +37,8 @@ namespace Terrain
         virtual void unloadCell(int x, int y);
 
         View* createView();
-        void preload(View* view, const osg::Vec3f& eyePoint, std::atomic<bool>& abort);
+
+        void preload(View* view, const osg::Vec3f& viewPoint, std::atomic<bool>& abort);
 
         void reportStats(unsigned int frameNumber, osg::Stats* stats);
 

components/terrain/terraingrid.cpp

@@ -15,7 +15,7 @@ class MyView : public View
 public:
     osg::ref_ptr<osg::Node> mLoaded;
 
-    virtual void reset(unsigned int frame) {}
+    virtual void reset() {}
 };
 
 TerrainGrid::TerrainGrid(osg::Group* parent, osg::Group* compileRoot, Resource::ResourceSystem* resourceSystem, Storage* storage, int nodeMask, int preCompileMask, int borderMask)

components/terrain/viewdata.cpp

@@ -7,7 +7,7 @@ ViewData::ViewData()
     : mNumEntries(0)
     , mFrameLastUsed(0)
     , mChanged(false)
-    , mHasEyePoint(false)
+    , mHasViewPoint(false)
 {
 
 }
@@ -17,6 +17,15 @@ ViewData::~ViewData()
 
 }
 
+void ViewData::copyFrom(const ViewData& other)
+{
+    mNumEntries = other.mNumEntries;
+    mEntries = other.mEntries;
+    mChanged = other.mChanged;
+    mHasViewPoint = other.mHasViewPoint;
+    mViewPoint = other.mViewPoint;
+}
+
 void ViewData::add(QuadTreeNode *node, bool visible)
 {
     unsigned int index = mNumEntries++;
@@ -44,23 +53,23 @@ bool ViewData::hasChanged() const
     return mChanged;
 }
 
-bool ViewData::hasEyePoint() const
+bool ViewData::hasViewPoint() const
 {
-    return mHasEyePoint;
+    return mHasViewPoint;
 }
 
-void ViewData::setEyePoint(const osg::Vec3f &eye)
+void ViewData::setViewPoint(const osg::Vec3f &viewPoint)
 {
-    mEyePoint = eye;
-    mHasEyePoint = true;
+    mViewPoint = viewPoint;
+    mHasViewPoint = true;
 }
 
-const osg::Vec3f& ViewData::getEyePoint() const
+const osg::Vec3f& ViewData::getViewPoint() const
 {
-    return mEyePoint;
+    return mViewPoint;
 }
 
-void ViewData::reset(unsigned int frame)
+void ViewData::reset()
 {
     // clear any unused entries
     for (unsigned int i=mNumEntries; i<mEntries.size(); ++i)
@@ -69,8 +78,6 @@ void ViewData::reset(unsigned int frame)
     // reset index for next frame
     mNumEntries = 0;
     mChanged = false;
-
-    mFrameLastUsed = frame;
 }
 
 void ViewData::clear()
@@ -80,6 +87,7 @@ void ViewData::clear()
     mNumEntries = 0;
     mFrameLastUsed = 0;
     mChanged = false;
+    mHasViewPoint = false;
 }
 
 bool ViewData::contains(QuadTreeNode *node)
@@ -112,17 +120,42 @@ bool ViewData::Entry::set(QuadTreeNode *node, bool visible)
     }
 }
 
-ViewData *ViewDataMap::getViewData(osg::Object *viewer)
+bool suitable(ViewData* vd, const osg::Vec3f& viewPoint, float& maxDist)
+{
+    return vd->hasViewPoint() && (vd->getViewPoint() - viewPoint).length2() < maxDist*maxDist;
+}
+
+ViewData *ViewDataMap::getViewData(osg::Object *viewer, const osg::Vec3f& viewPoint, bool& needsUpdate)
 {
     Map::const_iterator found = mViews.find(viewer);
+    ViewData* vd = nullptr;
     if (found == mViews.end())
     {
-        ViewData* vd = createOrReuseView();
+        vd = createOrReuseView();
+        vd->setViewer(viewer);
         mViews[viewer] = vd;
-        return vd;
     }
     else
-        return found->second;
+        vd = found->second;
+
+    if (!suitable(vd, viewPoint, mReuseDistance))
+    {
+        for (Map::const_iterator other = mViews.begin(); other != mViews.end(); ++other)
+        {
+            if (suitable(other->second, viewPoint, mReuseDistance) && other->second->getNumEntries())
+            {
+                vd->copyFrom(*other->second);
+                needsUpdate = false;
+                return vd;
+            }
+        }
+        vd->setViewPoint(viewPoint);
+        needsUpdate = true;
+    }
+    else
+        needsUpdate = false;
+
+    return vd;
 }
 
 ViewData *ViewDataMap::createOrReuseView()
@@ -168,9 +201,16 @@ void ViewDataMap::setDefaultViewer(osg::Object *viewer)
     mDefaultViewer = viewer;
 }
 
-ViewData* ViewDataMap::getDefaultView()
+bool ViewDataMap::getDefaultViewPoint(osg::Vec3f& viewPoint)
 {
-    return getViewData(mDefaultViewer);
+     Map::const_iterator found = mViews.find(mDefaultViewer);
+     if (found != mViews.end() && found->second->hasViewPoint())
+     {
+        viewPoint = found->second->getViewPoint();
+        return true;
+     }
+     else
+        return false;
 }
 
 

components/terrain/viewdata.hpp

@@ -21,12 +21,14 @@ namespace Terrain
 
         void add(QuadTreeNode* node, bool visible);
 
-        void reset(unsigned int frame);
+        void reset();
 
         void clear();
 
         bool contains(QuadTreeNode* node);
 
+        void copyFrom(const ViewData& other);
+
         struct Entry
         {
             Entry();
@@ -45,28 +47,34 @@ namespace Terrain
         Entry& getEntry(unsigned int i);
 
         unsigned int getFrameLastUsed() const { return mFrameLastUsed; }
+        void finishFrame(unsigned int frame) { mFrameLastUsed = frame; mChanged = false; }
 
         /// @return Have any nodes changed since the last frame
         bool hasChanged() const;
 
-        bool hasEyePoint() const;
+        bool hasViewPoint() const;
 
-        void setEyePoint(const osg::Vec3f& eye);
-        const osg::Vec3f& getEyePoint() const;
+        void setViewPoint(const osg::Vec3f& viewPoint);
+        const osg::Vec3f& getViewPoint() const;
 
     private:
         std::vector<Entry> mEntries;
         unsigned int mNumEntries;
         unsigned int mFrameLastUsed;
         bool mChanged;
-        osg::Vec3f mEyePoint;
-        bool mHasEyePoint;
+        osg::Vec3f mViewPoint;
+        bool mHasViewPoint;
+        float mReuseDistance;
     };
 
     class ViewDataMap : public osg::Referenced
     {
     public:
-        ViewData* getViewData(osg::Object* viewer);
+        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.
+        {}
+
+        ViewData* getViewData(osg::Object* viewer, const osg::Vec3f& viewPoint, bool& needsUpdate);
 
         ViewData* createOrReuseView();
 
@@ -76,7 +84,7 @@ namespace Terrain
 
         void setDefaultViewer(osg::Object* viewer);
 
-        ViewData* getDefaultView();
+        bool getDefaultViewPoint(osg::Vec3f& viewPoint);
 
     private:
         std::list<ViewData> mViewVector;
@@ -84,6 +92,8 @@ namespace Terrain
         typedef std::map<osg::ref_ptr<osg::Object>, ViewData*> Map;
         Map mViews;
 
+        float mReuseDistance;
+
         std::deque<ViewData*> mUnusedViews;
 
         osg::ref_ptr<osg::Object> mDefaultViewer;

components/terrain/world.hpp

@@ -8,6 +8,7 @@
 #include <atomic>
 #include <memory>
 #include <set>
+#include <atomic>
 
 #include "defs.hpp"
 #include "cellborder.hpp"
@@ -48,7 +49,7 @@ namespace Terrain
         virtual ~View() {}
 
         /// Reset internal structure so that the next addition to the view will override the previous frame's contents.
-        virtual void reset(unsigned int frame) = 0;
+        virtual void reset() = 0;
     };
 
     /**
@@ -102,7 +103,8 @@ namespace Terrain
         virtual View* createView() { return nullptr; }
 
         /// @note Thread safe, as long as you do not attempt to load into the same view from multiple threads.
-        virtual void preload(View* view, const osg::Vec3f& eyePoint, std::atomic<bool>& abort) {}
+
+        virtual void preload(View* view, const osg::Vec3f& viewPoint, std::atomic<bool>& abort) {}
 
         virtual void reportStats(unsigned int frameNumber, osg::Stats* stats) {}