Added support for occluders occluding other occluders, which helps reduce

the number of occluder that will be used in cull traversal to only the
ones that will be effective. Note. Holes in occluders arn't handled in
this occluder occlusion test, will implement this later.

include/osg/CollectOccludersVisitor

@@ -8,6 +8,8 @@
 #include <osg/NodeVisitor>
 #include <osg/CullStack>
 
+#include <set>
+
 namespace osg {
 
 class SG_EXPORT CollectOccludersVisitor : public osg::NodeVisitor, public osg::CullStack
@@ -15,6 +17,8 @@ class SG_EXPORT CollectOccludersVisitor : public osg::NodeVisitor, public osg::C
     public:
 
 
+        typedef std::set<ShadowVolumeOccluder> ShadowVolumeOccluderSet;
+
         CollectOccludersVisitor();
         virtual ~CollectOccludersVisitor();
 
@@ -37,9 +41,12 @@ class SG_EXPORT CollectOccludersVisitor : public osg::NodeVisitor, public osg::C
         void setCreateDrawablesOnOccludeNodes(bool flag) { _createDrawables=flag; }
         bool getCreateDrawablesOnOccludeNodes() const { return _createDrawables; }
 
-        void setCollectedOcculderList(const ShadowVolumeOccluderList& svol) { _occluderList = svol; }
-        ShadowVolumeOccluderList& getCollectedOccluderList() { return _occluderList; }
-        const ShadowVolumeOccluderList& getCollectedOccluderList() const { return _occluderList; }
+        void setCollectedOcculderList(const ShadowVolumeOccluderSet& svol) { _occluderSet = svol; }
+        ShadowVolumeOccluderSet& getCollectedOccluderSet() { return _occluderSet; }
+        const ShadowVolumeOccluderSet& getCollectedOccluderSet() const { return _occluderSet; }
+
+        /** remove occluded occluders for the collected occluders list.*/
+        void removeOccludedOccluders();
 
 
     protected:
@@ -66,7 +73,7 @@ class SG_EXPORT CollectOccludersVisitor : public osg::NodeVisitor, public osg::C
 
         float                       _minimumShadowOccluderVolume;
         bool                        _createDrawables;
-        ShadowVolumeOccluderList    _collectedOccluderList;
+        ShadowVolumeOccluderSet     _occluderSet;
 
 };
 

include/osg/Polytope

@@ -18,16 +18,18 @@ class SG_EXPORT Polytope
 
     public:
 
-        typedef unsigned int ClippingMask;
-        typedef std::vector<Plane> PlaneList;
-        typedef fast_back_stack<ClippingMask> MaskStack;
+        typedef unsigned int                    ClippingMask;
+        typedef std::vector<Plane>              PlaneList;
+        typedef std::vector<Vec3>               VertexList;
+        typedef fast_back_stack<ClippingMask>   MaskStack;
 
         inline Polytope() {setupMask();}
 
         inline Polytope(const Polytope& cv) : 
             _maskStack(cv._maskStack),
             _resultMask(cv._resultMask),
-            _planeList(cv._planeList) {}
+            _planeList(cv._planeList),
+            _referenceVertexList(cv._referenceVertexList) {}
         
         inline Polytope(const PlaneList& pl) : _planeList(pl) {setupMask();}
 
@@ -41,6 +43,7 @@ class SG_EXPORT Polytope
             _maskStack = cv._maskStack;
             _resultMask = cv._resultMask;
             _planeList = cv._planeList;
+            _referenceVertexList = cv._referenceVertexList;
             return *this;
         }
         
@@ -77,6 +80,14 @@ class SG_EXPORT Polytope
 
         inline const PlaneList& getPlaneList() const { return _planeList; }
 
+
+        inline void setReferenceVertexList(VertexList& vertices) { _referenceVertexList=vertices; }
+
+        inline VertexList& getReferenceVertexList() { return _referenceVertexList; }
+        
+        inline const VertexList& getReferenceVertexList() const { return _referenceVertexList; }
+
+
         inline void setupMask()
         {
             _resultMask = 0;
@@ -312,6 +323,7 @@ class SG_EXPORT Polytope
         MaskStack                           _maskStack;
         ClippingMask                        _resultMask;
         PlaneList                           _planeList;
+        VertexList                          _referenceVertexList;
 
 };
 

include/osg/ShadowVolumeOccluder

@@ -33,6 +33,8 @@ class SG_EXPORT ShadowVolumeOccluder
             _volume(0.0f) {}
 
 
+        bool operator < (const ShadowVolumeOccluder& svo) const { return getVolume()>svo.getVolume(); } // not greater volume first. 
+
         /** compute the shadow volume occluder. */
         bool computeOccluder(const NodePath& nodePath,const ConvexPlanerOccluder& occluder,CullStack& cullStack,bool createDrawables=false);
         
@@ -86,7 +88,7 @@ class SG_EXPORT ShadowVolumeOccluder
         }
         
 
-    protected:
+//    protected:
 
         float                   _volume;
         NodePath                _nodePath;