source: GTP/trunk/App/Demos/Vis/FriendlyCulling/src/OcclusionQuery.h @ 3258

#ifndef _OcclusionQuery_H__
#define _OcclusionQuery_H__

#include <vector>
#include "common.h"


namespace CHCDemoEngine 
{ 

class BvhNode;

/** This class is an implementation for single node queries and multiqueries.
        @remark the class encapsulates hardware occlusion query calls.
*/
class OcclusionQuery
{
        friend class QueryHandler;

public:
        /** constructor requesting an opengl occlusion query.
        */
        OcclusionQuery();

        virtual ~OcclusionQuery();
        /** Returns true if the query result is available.
        */
        bool ResultAvailable() const;
        /** Returns number of visible pixels.
        */
        unsigned int GetQueryResult() const;
        /** Starts the query. Everything drawn inbetween start and end is
                queried.
        */
        void BeginQuery() const;
        /** Ends the query.
        */
        void EndQuery() const;
        /** Returns id of this query.
        */
        unsigned int GetQueryId() const;
        /** Returns the first node of the multiquery
        */
        inline BvhNode *GetFrontNode() const { return mNodes[0]; }
        /** Returns nodes by reference
        */
        inline const BvhNodeContainer &GetNodes() const { return mNodes; }
        /** Reset the list of nodes associated with this query.
        */
        inline void Reset() { mNodes.clear(); }
        /** Adds a node to the query.
        */
        inline void AddNode(BvhNode *node) { mNodes.push_back(node); }
        /** Returns the size of the multiquery.
        */
        inline int GetSize() const { return (int)mNodes.size(); }

        inline bool IsEmpty() const { return GetSize() == 0; }


protected:
        /** Constructor taking an already allocated query id.
        */
        OcclusionQuery(unsigned int id): mQueryId(id) { }

        ///////
        //-- members

        /// all nodes that are tested with the same query
        BvhNodeContainer mNodes; 
        // the query associated with this test
        unsigned int mQueryId;
};


class QueryHandler
{
public:

        QueryHandler();
        ~QueryHandler() { DestroyQueries(); }

        OcclusionQuery *RequestQuery();

        /** Must be called every frame.
        */
        void ResetQueries();
        /** Destroys all the queries.
        */
        void DestroyQueries();

protected:
        
        /** allocates n queries in advance
        */
        void Allocate(int n);


        ////////////////

        int mCurrentQueryIdx;

        QueryContainer mOcclusionQueries;
};


} // namespace 
#endif // OcclusionQuery_H