source: trunk/VUT/work/ogre_changes/RenderSystems/Direct3D9/include/OgreD3D9HardwareOcclusionQuery.h @ 115

/*
-----------------------------------------------------------------------------
This source file is part of OGRE
    (Object-oriented Graphics Rendering Engine)
For the latest info, see http://ogre.sourceforge.net/

Copyright (c) 2000-2005 The OGRE Team
Also see acknowledgements in Readme.html

This program is free software; you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License as published by the Free Software
Foundation; either version 2 of the License, or (at your option) any later
version.

This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with
this program; if not, write to the Free Software Foundation, Inc., 59 Temple
Place - Suite 330, Boston, MA 02111-1307, USA, or go to
http://www.gnu.org/copyleft/lesser.txt.
-----------------------------------------------------------------------------
*/

#ifndef _D3D9HARWAREOCCLUSIONQUERY_H__
#define _D3D9HARWAREOCCLUSIONQUERY_H__

#include "OgreD3D9Prerequisites.h"
#include "OgreHardwareOcclusionQuery.h"


namespace Ogre {

// If you use multiple rendering passes you can test only the first pass and all other passes don't have to be rendered 
        // if the first pass resultet has too few pixels visible.

// Be sure to render all occlluder first and whats out so the RenderQue don't switch places on 
// the occluding objects and the tested objects because it thinks it's more effective..

/**
  * This is a class that is the DirectX9 implementation of 
  * hardware occlusion testing.
  *
  * @author Lee Sandberg, email lee@abcmedia.se
        *
        * Updated on 12/7/2004 by Chris McGuirk
  */
class D3D9HardwareOcclusionQuery : public HardwareOcclusionQuery
{
//----------------------------------------------------------------------
// Public methods
//--
public:

        /**
          * Default object constructor
          * 
          */
        D3D9HardwareOcclusionQuery( IDirect3DDevice9* pD3DDevice );

        /**
          * Object destructor
          */
        ~D3D9HardwareOcclusionQuery();

        //------------------------------------------------------------------
        // Occlusion query functions (see base class documentation for this)
        //--

        void beginOcclusionQuery();     
        void endOcclusionQuery();
                bool pullOcclusionQuery( unsigned int* NumOfFragments, const HW_OCCLUSIONQUERY flag = HWOCCLUSIONQUERY_FLUSH);
                unsigned int getLastQuerysPixelcount() { return mPixelCount; }

                // These functions are optional, it's a simple filter that simply skips some hardware occlusion tests on visible objects only
                // It's easy to use if you don't have to keep track of which objects are visible (can be skipped) and what objects arn't visible..
                // (None visible objects and object you introduce for the first time have always to be tested although the cheapest possible 
                // LOD (Level Of Detail) mesh and material-wise). 

        /**
          *   
                * Remarks This function allows you to set how often the hardware occlusion query is sent to the driver
          * if you set it to 0 every hw occlusion test is acctually made. If you set it to 1 only the half of your queries are sent 
                * 2 will result in 25% of all queries to acctualy be sent. 
                * This functionality is here because this class can keep track on visible and none visible objects for you.
          * Once you you set the SkipRate for any hardware occlusion instance it effects all others.
          */

                void setSkipRate( int skip ) { mSkipInterval = skip; }                  // Using 2 only 50 % of the tests are actully made and 3 results in only 33% of the tests. So on.
                int      getSkipRate() { return mSkipInterval; } 

#ifdef GTP_VISIBILITY_MODIFIED_OGRE
        bool pullOcclusionQuery( unsigned int* NumOfFragments, const bool waitForResult, const HW_OCCLUSIONQUERY flag = HWOCCLUSIONQUERY_FLUSH ); 
#endif // GTP_VISIBILITY_MODIFIED_OGRE
//----------------------------------------------------------------------
// Protected members
//--
protected:

                unsigned int            mPixelCount;            
                IDirect3DQuery9*        mpQuery;
                IDirect3DDevice9*   mpDevice;
                int                                     mSkipCounter;
                int                                     mSkipInterval;
                bool                            mHasOcclusionSupport;
};


}


#endif