Added _maximumNumberOfActiveOccluders variable to CollectOccludersVisitor(), to

limit the maximum number of occluders used in the cull traversal, default is
now 10.

Added set/getCollectOccluderVisitor() method into SceneView to allow control
of the the settings of the CollectOccluderVisitor.

include/osg/CollectOccludersVisitor

@@ -46,10 +46,15 @@ class SG_EXPORT CollectOccludersVisitor : public osg::NodeVisitor, public osg::C
         virtual void apply(osg::LOD& node);
         virtual void apply(osg::OccluderNode& node);
 
-
+        /** Set the minimum shadow occluder volume that an active occluder must have.
+          * volume is units relative the clip space volume where 1.0 is the whole clip space.*/
         void setMinimumShadowOccluderVolume(float vol) { _minimumShadowOccluderVolume = vol; }
         float getMinimumShadowOccluderVolume() const { return _minimumShadowOccluderVolume; }
 
+        /** Set the maximum number of occluders to have active for culling purposes.*/
+        void setMaximumNumberOfActiveOccluders(unsigned int num) { _maximumNumberOfActiveOccluders = num; }
+        unsigned int getMaximumNumberOfActiveOccluders() const { return _maximumNumberOfActiveOccluders; }
+
         void setCreateDrawablesOnOccludeNodes(bool flag) { _createDrawables=flag; }
         bool getCreateDrawablesOnOccludeNodes() const { return _createDrawables; }
 
@@ -57,7 +62,9 @@ class SG_EXPORT CollectOccludersVisitor : public osg::NodeVisitor, public osg::C
         ShadowVolumeOccluderSet& getCollectedOccluderSet() { return _occluderSet; }
         const ShadowVolumeOccluderSet& getCollectedOccluderSet() const { return _occluderSet; }
 
-        /** remove occluded occluders for the collected occluders list.*/
+        /** remove occluded occluders for the collected occluders list,
+          * and then discard of all but MaximumNumberOfActiveOccluders of occluders,
+          * discarding the occluders with the lowests shadow occluder volume .*/
         void removeOccludedOccluders();
 
 
@@ -84,6 +91,7 @@ class SG_EXPORT CollectOccludersVisitor : public osg::NodeVisitor, public osg::C
         }
 
         float                       _minimumShadowOccluderVolume;
+        unsigned                    _maximumNumberOfActiveOccluders;
         bool                        _createDrawables;
         ShadowVolumeOccluderSet     _occluderSet;
 

include/osgUtil/SceneView

@@ -19,6 +19,7 @@
 #include <osg/Light>
 #include <osg/FrameStamp>
 #include <osg/DisplaySettings>
+#include <osg/CollectOccludersVisitor>
 
 
 #include <osgUtil/CullVisitor>
@@ -234,6 +235,10 @@ class OSGUTIL_EXPORT SceneView : public osg::Referenced
         void setCullVisitorRight(osgUtil::CullVisitor* cv) { _cullVisitorRight = cv; }
         osgUtil::CullVisitor* getCullVisitorRight() { return _cullVisitorRight.get(); }
         const osgUtil::CullVisitor* getCullVisitorRight() const { return _cullVisitorRight.get(); }
+        
+        void setCollectOccludersVisitor(osg::CollectOccludersVisitor* cov) { _collectOccludersVisistor = cov; }
+        osg::CollectOccludersVisitor* getCollectOccludersVisitor() { return _collectOccludersVisistor.get(); }
+        const osg::CollectOccludersVisitor* getCollectOccludersVisitor() const { return _collectOccludersVisistor.get(); }
 
 
         void setRenderGraph(osgUtil::RenderGraph* rg) { _rendergraph = rg; }
@@ -465,8 +470,11 @@ class OSGUTIL_EXPORT SceneView : public osg::Referenced
         osg::ref_ptr<osgUtil::RenderGraph>          _rendergraphRight;
         osg::ref_ptr<osgUtil::RenderStage>          _renderStageRight;
 
+        osg::ref_ptr<osg::CollectOccludersVisitor>  _collectOccludersVisistor;
+        
         osg::ref_ptr<osg::FrameStamp>               _frameStamp;
 
+
         osg::Vec4                                   _backgroundColor;
 
         CullVisitor::ComputeNearFarMode             _computeNearFar;

src/osg/CollectOccludersVisitor.cpp

@@ -31,6 +31,7 @@ CollectOccludersVisitor::CollectOccludersVisitor():
                    SMALL_FEATURE_CULLING);
     
     _minimumShadowOccluderVolume = 0.005f;
+    _maximumNumberOfActiveOccluders = 10;
     _createDrawables = false;
     
 }
@@ -42,6 +43,7 @@ CollectOccludersVisitor::~CollectOccludersVisitor()
 void CollectOccludersVisitor::reset()
 {
     CullStack::reset();
+    _occluderSet.clear();
 }
 
 float CollectOccludersVisitor::getDistanceToEyePoint(const Vec3& pos, bool withLODScale) const
@@ -236,4 +238,16 @@ void CollectOccludersVisitor::removeOccludedOccluders()
             
         }
     }
+    
+
+    if (_occluderSet.size()<=_maximumNumberOfActiveOccluders) return;
+    
+    // move the iterator to the _maximumNumberOfActiveOccluders th occluder.
+    occludeeItr = _occluderSet.begin();
+    for(unsigned int i=0;i<_maximumNumberOfActiveOccluders;++i)
+        ++occludeeItr;
+        
+    // discard last occluders.
+    _occluderSet.erase(occludeeItr,_occluderSet.end());
+    
 }

src/osgUtil/SceneView.cpp

@@ -449,35 +449,38 @@ void SceneView::cullStage(const osg::Matrixd& projection,const osg::Matrixd& mod
     {
         //std::cout << "Scene graph contains occluder nodes, searching for them"<<std::endl;
         
-        osg::CollectOccludersVisitor cov;
         
-        cov.setFrameStamp(_frameStamp.get());
+        if (!_collectOccludersVisistor) _collectOccludersVisistor = new osg::CollectOccludersVisitor;
+        
+        _collectOccludersVisistor->reset();
+        
+        _collectOccludersVisistor->setFrameStamp(_frameStamp.get());
 
         // use the frame number for the traversal number.
         if (_frameStamp.valid())
         {
-             cov.setTraversalNumber(_frameStamp->getFrameNumber());
+             _collectOccludersVisistor->setTraversalNumber(_frameStamp->getFrameNumber());
         }
 
-        cov.pushViewport(_viewport.get());
-        cov.pushProjectionMatrix(proj.get());
-        cov.pushModelViewMatrix(mv.get());
+        _collectOccludersVisistor->pushViewport(_viewport.get());
+        _collectOccludersVisistor->pushProjectionMatrix(proj.get());
+        _collectOccludersVisistor->pushModelViewMatrix(mv.get());
 
         // traverse the scene graph to search for occluder in there new positions.
-        _sceneData->accept(cov);
+        _sceneData->accept(*_collectOccludersVisistor);
 
-        cov.popModelViewMatrix();
-        cov.popProjectionMatrix();
-        cov.popViewport();
+        _collectOccludersVisistor->popModelViewMatrix();
+        _collectOccludersVisistor->popProjectionMatrix();
+        _collectOccludersVisistor->popViewport();
         
         // sort the occluder from largest occluder volume to smallest.
-        cov.removeOccludedOccluders();
+        _collectOccludersVisistor->removeOccludedOccluders();
         
         
-        //std::cout << "finished searching for occluder - found "<<cov.getCollectedOccluderSet().size()<<std::endl;
+        osg::notify(osg::INFO) << "finished searching for occluder - found "<<_collectOccludersVisistor->getCollectedOccluderSet().size()<<std::endl;
            
         cullVisitor->getOccluderList().clear();
-        std::copy(cov.getCollectedOccluderSet().begin(),cov.getCollectedOccluderSet().end(), std::back_insert_iterator<CullStack::OccluderList>(cullVisitor->getOccluderList()));
+        std::copy(_collectOccludersVisistor->getCollectedOccluderSet().begin(),_collectOccludersVisistor->getCollectedOccluderSet().end(), std::back_insert_iterator<CullStack::OccluderList>(cullVisitor->getOccluderList()));
     }