source: OGRE/trunk/ogre_changes/RenderSystems/Direct3D9/src/OgreD3D9HardwareOcclusionQuery.cpp @ 193

/*
-----------------------------------------------------------------------------
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.
-----------------------------------------------------------------------------
*/
#include "OgreD3D9HardwareOcclusionQuery.h"
#include "OgreRenderSystemCapabilities.h"
#include "OgreException.h"

namespace Ogre {

/**
  * This is a class that is the DirectX9 implementation of 
  * hardware occlusion testing.
  *
  * @author Lee Sandberg
        *
        * Updated on 12/7/2004 by Chris McGuirk
  */

/**
  * Default object constructor
  */
D3D9HardwareOcclusionQuery::D3D9HardwareOcclusionQuery( IDirect3DDevice9* pD3DDevice ) 
{ 
                mpDevice = pD3DDevice;
                mPixelCount = 0; 
                mSkipCounter = 0;
                mSkipInterval = 0;
                mHasOcclusionSupport = false;

                // create the occlusion query
                HRESULT hr = mpDevice->CreateQuery(D3DQUERYTYPE_OCCLUSION, &mpQuery);

        if ( hr != D3D_OK ) 
        {
                        mHasOcclusionSupport = false;
        }
        else 
        {
                        mHasOcclusionSupport = true;
        }
}

/**
  * Object destructor
  */
D3D9HardwareOcclusionQuery::~D3D9HardwareOcclusionQuery() 
{ 
                SAFE_RELEASE(mpQuery); 
}

//------------------------------------------------------------------
// Occlusion query functions (see base class documentation for this)
//--
void D3D9HardwareOcclusionQuery::beginOcclusionQuery() 
{ 
                // Make it fail silently if hardware occlusion isn't supported
                if(mHasOcclusionSupport)
        {
#ifndef GTP_VISIBILITY_MODIFIED_OGRE
                        // Counter starts at 0 again at mSkipInterval 
                        if(mSkipCounter == mSkipInterval) 
#else
                        if (mSkipCounter >= mSkipInterval)  // otherwise no query ever issued if mSkipInterval = 0 !
#endif // GTP_VISIBILITY_MODIFIED_OGRE
                {
                                mSkipCounter = 0; 
}
                        if (mSkipCounter == 0)
                {
                                mpQuery->Issue(D3DISSUE_BEGIN); 
                }
        }
        
}

        void D3D9HardwareOcclusionQuery::endOcclusionQuery() 
        {
                // Make it fail silently if hardware occlusion isn't supported
                if(mHasOcclusionSupport)
                        {
                        if(mSkipCounter == 0)
                        { 
                                mpQuery->Issue(D3DISSUE_END); 
        }

                        // The skip counter is increased
                        mSkipCounter++; 
        }
}

//------------------------------------------------------------------
        // This version of pullOcclusionQuery causes the DX9 API/Driver to not flush all commands to the 3D card
// to allow a fast result from the query, but the batching of API calls to the card will be normal. 
        // But the query wont be processed until the card recives the query in the next batch.
// Note: OpenGL dosn't use this flag at all so the application running OpenGL won't display any different behaviour.
//--
bool D3D9HardwareOcclusionQuery::pullOcclusionQuery( unsigned int* NumOfFragments, const HW_OCCLUSIONQUERY flag  ) 
{
        HRESULT hr;

                // Make it fail silently if hardware occlusion isn't supported
                if(mHasOcclusionSupport)
        {
                        DWORD d3dFlags = (flag == HWOCCLUSIONQUERY_FLUSH) ? D3DGETDATA_FLUSH : 0;
        
                        // run until success (http://www.gamedev.net/reference/programming/features/occlusionculling/page2.asp)
                        while(hr = mpQuery->GetData( NumOfFragments, sizeof( NumOfFragments ), d3dFlags) == S_FALSE);

                        mPixelCount = *NumOfFragments;
                        }
                        else 
                        { 
                        // fail silently if not supported, assume visible i suppose
                        mPixelCount = 100000;
                        }

                return true;
        }

#ifdef GTP_VISIBILITY_MODIFIED_OGRE
//------------------------------------------------------------------
        bool D3D9HardwareOcclusionQuery::pullOcclusionQuery( unsigned int* NumOfFragments, const bool waitForResult, 
                                                                                                             const HW_OCCLUSIONQUERY flag ) 
        {
                HRESULT hr = S_OK;
                DWORD queryFlag = (flag == HWOCCLUSIONQUERY_FLUSH) ? D3DGETDATA_FLUSH : 0;

                if (mHasOcclusionSupport)       // In case hardware occlusion isn't supported
                {       
                        do
                        {
                                hr = mpQuery->GetData(NumOfFragments, sizeof(NumOfFragments), queryFlag);
                }
                        while(waitForResult && (hr == S_FALSE));
                
                        mPixelCount = *NumOfFragments;
                }
                else
                {
                        mPixelCount = 100000; // every object is visible
                }
        
                return hr == S_OK;
        }


#endif // GTP_VISIBILITY_MODIFIED_OGRE


}