Add preloading implementation to QuadTreeWorld

components/terrain/quadtreenode.cpp

@@ -108,7 +108,7 @@ void QuadTreeNode::traverse(osg::NodeVisitor &nv)
             return;
     }
 
-    if ((mLodCallback && mLodCallback->isSufficientDetail(this, nv)) || !getNumChildren())
+    if ((mLodCallback && mLodCallback->isSufficientDetail(this, nv.getEyePoint())) || !getNumChildren())
         getView(nv)->add(this, true);
     else
         osg::Group::traverse(nv);

components/terrain/quadtreenode.hpp

@@ -23,7 +23,7 @@ namespace Terrain
     public:
         virtual ~LodCallback() {}
 
-        virtual bool isSufficientDetail(QuadTreeNode *node, osg::NodeVisitor &nv) = 0;
+        virtual bool isSufficientDetail(QuadTreeNode *node, const osg::Vec3f& eyePoint) = 0;
     };
 
     class ViewDataMap;

components/terrain/quadtreeworld.cpp

@@ -70,9 +70,9 @@ namespace Terrain
 class DefaultLodCallback : public LodCallback
 {
 public:
-    virtual bool isSufficientDetail(QuadTreeNode* node, osg::NodeVisitor& nv)
+    virtual bool isSufficientDetail(QuadTreeNode* node, const osg::Vec3f& eyePoint)
     {
-        float dist = distance(node->getBoundingBox(), nv.getEyePoint());
+        float dist = distance(node->getBoundingBox(), eyePoint);
         int nativeLodLevel = Log2(static_cast<unsigned int>(node->getSize()*4));
         int lodLevel = Log2(static_cast<unsigned int>(dist/2048.0));
 
@@ -238,20 +238,22 @@ QuadTreeWorld::~QuadTreeWorld()
 }
 
 
-void traverse(QuadTreeNode* node, ViewData* vd, osgUtil::CullVisitor* cv, bool visible)
+void traverse(QuadTreeNode* node, ViewData* vd, osg::NodeVisitor* nv, const osg::Vec3f& eyePoint, bool visible)
 {
     if (!node->hasValidBounds())
         return;
 
-    visible = visible && !cv->isCulled(node->getBoundingBox());
-    bool stopTraversal = (node->getLodCallback() && node->getLodCallback()->isSufficientDetail(node, *cv)) || !node->getNumChildren();
+    if (nv && nv->getVisitorType() == osg::NodeVisitor::CULL_VISITOR)
+        visible = visible && !static_cast<osgUtil::CullVisitor*>(nv)->isCulled(node->getBoundingBox());
+
+    bool stopTraversal = (node->getLodCallback() && node->getLodCallback()->isSufficientDetail(node, eyePoint)) || !node->getNumChildren();
 
     if (stopTraversal)
         vd->add(node, visible);
     else
     {
         for (unsigned int i=0; i<node->getNumChildren(); ++i)
-            traverse(node->getChild(i), vd, cv, visible);
+            traverse(node->getChild(i), vd, nv, eyePoint, visible);
     }
 }
 
@@ -313,7 +315,7 @@ void QuadTreeWorld::accept(osg::NodeVisitor &nv)
     if (nv.getVisitorType() == osg::NodeVisitor::CULL_VISITOR)
     {
         osgUtil::CullVisitor* cv = static_cast<osgUtil::CullVisitor*>(&nv);
-        traverse(mRootNode.get(), vd, cv, true);
+        traverse(mRootNode.get(), vd, cv, cv->getEyePoint(), true);
     }
     else
         mRootNode->traverse(nv);
@@ -374,6 +376,31 @@ void QuadTreeWorld::enable(bool enabled)
         mRootNode->setNodeMask(enabled ? ~0 : 0);
 }
 
+View* QuadTreeWorld::createView()
+{
+    ViewData* vd = mViewDataMap->createOrReuseView();
+    vd->setPersistent(true);
+    return vd;
+}
+
+void QuadTreeWorld::removeView(View *view)
+{
+    mViewDataMap->removeView(static_cast<ViewData*>(view));
+}
+
+void QuadTreeWorld::preload(View *view, const osg::Vec3f &eyePoint)
+{
+    ensureQuadTreeBuilt();
+
+    ViewData* vd = static_cast<ViewData*>(view);
+    traverse(mRootNode.get(), vd, NULL, eyePoint, false);
+
+    for (unsigned int i=0; i<vd->getNumEntries(); ++i)
+    {
+        ViewData::Entry& entry = vd->getEntry(i);
+        loadRenderingNode(entry, vd, mChunkManager.get());
+    }
+}
 
 
 }

components/terrain/quadtreeworld.hpp

@@ -28,6 +28,10 @@ namespace Terrain
 
         virtual void enable(bool enabled);
 
+        View* createView();
+        void removeView(View* view);
+        void preload(View* view, const osg::Vec3f& eyePoint);
+
     private:
         void ensureQuadTreeBuilt();
 

components/terrain/viewdata.cpp

@@ -12,6 +12,11 @@ ViewData::ViewData()
 
 }
 
+ViewData::~ViewData()
+{
+
+}
+
 void ViewData::add(QuadTreeNode *node, bool visible)
 {
     unsigned int index = mNumEntries++;
@@ -121,6 +126,13 @@ ViewData *ViewDataMap::createOrReuseView()
     }
 }
 
+void ViewDataMap::removeView(ViewData* vd)
+{
+    vd->setPersistent(false);
+    vd->clear();
+    mUnusedViews.push_back(vd);
+}
+
 void ViewDataMap::clearUnusedViews(unsigned int frame)
 {
     for (Map::iterator it = mViews.begin(); it != mViews.end(); )

components/terrain/viewdata.hpp

@@ -6,15 +6,18 @@
 
 #include <osg/Node>
 
+#include "world.hpp"
+
 namespace Terrain
 {
 
     class QuadTreeNode;
 
-    class ViewData
+    class ViewData : public View
     {
     public:
         ViewData();
+        ~ViewData();
 
         void add(QuadTreeNode* node, bool visible);
 
@@ -42,6 +45,7 @@ namespace Terrain
         Entry& getEntry(unsigned int i);
 
         bool getPersistent() const { return mPersistent; }
+        void setPersistent(bool persistent) { mPersistent = persistent; }
 
         osg::Object* getViewer() const { return mViewer.get(); }
         void setViewer(osg::Object* viewer) { mViewer = viewer; }
@@ -66,6 +70,7 @@ namespace Terrain
         ViewData* getViewData(osg::Object* viewer, bool ref);
 
         ViewData* createOrReuseView();
+        void removeView(ViewData* view);
 
         void clearUnusedViews(unsigned int frame);
 

components/terrain/world.hpp

@@ -28,6 +28,19 @@ namespace Terrain
     class ChunkManager;
     class CompositeMapRenderer;
 
+    /**
+     * @brief A View is a collection of rendering objects that are visible from a given camera/intersection.
+     * The base View class is part of the interface for usage in conjunction with preload feature.
+     */
+    class View
+    {
+    public:
+        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;
+    };
+
     /**
      * @brief The basic interface for a terrain world. How the terrain chunks are paged and displayed
      *  is up to the implementation.
@@ -66,6 +79,17 @@ namespace Terrain
 
         virtual void enable(bool enabled) {}
 
+        /// Create a View to use with preload feature. If a View is returned, it will remain valid until the user calls 'removeView' or the World is destroyed.
+        /// @note Not thread safe.
+        virtual View* createView() { return NULL; }
+
+        /// Remove a View that was previously created with 'createView'.
+        /// @note Not thread safe.
+        virtual void removeView(View* view) {}
+
+        /// @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) {}
+
         Storage* getStorage() { return mStorage; }
 
     protected: