source: trunk/VUT/OcclusionCullingSceneManager/include/OgreOcclusionCullingSceneTraverser.h @ 41

#ifndef _OcclusionCullingSceneTraverser_H__
#define _OcclusionCullingSceneTraverser_H__

#include "OgreSceneNode.h"
#include "OgreSceneManager.h"
#include "OgrePrerequisites.h"
#include "OgreSolidHalfBoundingBox.h"
#include "OgreCamera.h"
#include "OgreRenderSystem.h"
#include <queue>

using namespace std;

namespace Ogre {
        /**
                This class implements the compare operator for the priority queue.
                a lower distance has a higher value in the queue
        */
        template <typename T> class myless
        {
        public:
                myless(Camera *cam) { mCamera = cam; }
                //bool operator() (HierarchyNode *v1, HierarchyNode *v2) const
                bool operator() (T v1, T v2) const
                {
                        return v1->getSquaredViewDepth(mCamera) > v2->getSquaredViewDepth(mCamera);
                }
        private:
                Camera *mCamera;
        };

        typedef pair<SceneNode *, HardwareOcclusionQuery *> QueryPair;
        typedef priority_queue<SceneNode *, vector<SceneNode *>, myless<vector<SceneNode *>::value_type> > PriorityQueue;
        typedef queue<QueryPair> QueryQueue;
        /**
                Class which implements a scene mangager which uses occlusion queries for culling occluded objects
        */
        class OcclusionCullingSceneTraverser
        {
        public:
                /** Construction taking the current scene manager and the current rendersystem as argument
                @param sm current scene manager
                @param rsys current render system 
                */
                OcclusionCullingSceneTraverser(SceneManager *sm, RenderSystem *rsys);
                ~OcclusionCullingSceneTraverser();
        
                enum {RENDER_CULL_FRUSTUM, RENDER_STOP_AND_WAIT, RENDER_COHERENT, NUM_RENDERMODES};
                
                /** Renders the scene with the specified algorithm
                        @comment 
                        The algorithm type can be set with the parameter "Algorithm" and setOption.

                        The algorithm is one of:
                        RENDER_CULL_FRUSTUM: renders the scene with view frustum culling only
                        RENDER_STOP_AND_WAIT: renders the scene with the hierarchical stop and wait algorithm
                        RENDER_COHERENT: renders the scene with the coherent hierarchical algorithm
                        
                        @param cam current camera
                        @param root root of hierarchy 
                */
                void renderScene( Camera *cam, SceneNode *root );
        
                
                /** Sets the given option for the scene traverser.
                               @remarks
                        Options are:
                        "Algorithm", int *;                     
                */
                bool setOption( const String &, const void * );
                /** Gets the given option for the scene traverser.
                @remarks
                    See setOption
                */
                bool getOption( const String &, void * );
                bool getOptionKeys( StringVector &refKeys );
                
                /** Sets pointer to the current scene manager.
                @param the scene manager */
                void setSceneManager( SceneManager *sm );
                
                /** Sets pointer to the current render system 
                @param the rendersystem */
                void setRenderSystem( RenderSystem *rsys );
                
                /** Doing some necessary preprocessing.
                @comment e.g., initialises occlusion queries */
                void preprocess( void );

                /** Sets the current number of scene nodes in the scene.
                @param num number of scene nodes
                */
                void setNumSceneNodes(int num );

                /** Sets the required number of occlusion queries.
                @param num number occlusion queries
                */
                void setNumQueries( int num );

        protected:
                /** query mode (= without color) or RENDER_MODE */
                enum {MODE_QUERY, MODE_RENDER};
                /** returns true if node is leaf of the hierarchy */
                bool isLeaf( SceneNode *node );
                //HACK
                //unsigned int countSceneNodes(SceneNode *node);
                void traverseNode( Camera *cam, SceneNode *node );
                /** Renders current scene node 
                @param cam current camera
                @param node current scene node to be rendered
                */
                void renderSceneNode( Camera *cam, SceneNode *node);
                /** Sets rendering mode, e.g. query mode or render mode*/
                void setRenderingMode( int mode );
                /** Renders the scene with view frustum culling only. */
                void renderCullFrustum( Camera *cam );
                /** Renders the scene with the hierarchical stop and wait algorithm. */
                void renderStopAndWait( Camera *cam );
                /** Renders the scene with the coherent hierarchical algorithm and the query queye. */
                void renderCoherentWithQueue( Camera *cam );
                /** Issue a occlusion query for this node. 
                @param box the axis aligned bounding box of the node
                @wasVisible if the node was visible in previous frame
                */
                HardwareOcclusionQuery *issueOcclusionQuery( AxisAlignedBox *box, bool wasVisible );
                /** Pulls up the visibility from the child nodes. */
                void pullUpVisibility( SceneNode *node );
                /** delete all previously defined occlusion queries */
                void deleteQueries();
                /** Renders bounding box of specified node.
                @param box the bounding box of the scene node to be rendered */
                void renderBoundingBox( AxisAlignedBox *box );
                /** Returns one half of the bounding box.
                @param half the half index of the bouding box (0 or 1)
                */
                SolidHalfBoundingBox *getSolidHalfBoundingBox( int half );

                // we use a priority queue rather than a renderstack
                PriorityQueue *mDistanceQueue; 
                
                std::vector<HardwareOcclusionQuery *> mOcclusionQueries;
                // two halfes of a aabb
                SolidHalfBoundingBox *mHalfBoundingBox[2];      

                int mCurrentAlgorithm;

                unsigned int mFrameId;
                unsigned int mVisibilityThreshold;
                
                SceneManager *mSceneManager;
                RenderSystem *mRenderSystem;

                int mCurrentTestIdx;
                int mQueryMode;

                unsigned int mNumQueries;

                //--- statistics
                unsigned int mNumSceneNodes;
                unsigned int mNumTraversedNodes;
                unsigned int mNumQueryCulledNodes;
                unsigned int mNumFrustumCulledNodes;
                unsigned int mNumRenderedGeometry;
        };

}
#endif // OCCLUSIONCULLINGSCENEMANAGER_H