source: OGRE/trunk/ogrenew/RenderSystems/GL/src/OgreGLHardwareOcclusionQuery.cpp @ 657

/*
-----------------------------------------------------------------------------
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 "OgreGLHardwareOcclusionQuery.h"
#include "OgreException.h"

namespace Ogre {

bool GLHardwareOcclusionQuery::sUseArbQueries = false;
/**
  * This is a class that is the base class of the query class for 
  * hardware occlusion testing.
  *
  * @author Lee Sandberg email: lee@abcmedia.se
  *
  * Updated on 12/7/2004 by Chris McGuirk
  * - Implemented ARB_occlusion_query
  * Updated on 4/8/2005 by Tuan Kuranes email: tuan.kuranes@free.fr
  */

/**
  * Default object constructor
  * 
  */
GLHardwareOcclusionQuery::GLHardwareOcclusionQuery() 
{ 
        mPixelCount = 0; 
        mSkipCounter = 0;
        mSkipInterval = 0;

        // Check for hardware occlusion support
        // This is a hack to see if hw occlusion is supported. pointer is 0 if it's not supported.
        mHasOcclusionSupportARB = (glGenQueriesARB_ptr != 0);
        mHasOcclusionSupportNV = (glGenOcclusionQueriesNV_ptr != 0);

        if (sUseArbQueries && mHasOcclusionSupportARB)
                glGenQueriesARB_ptr(1, &mQueryID );     
        else if (!sUseArbQueries && mHasOcclusionSupportNV)
                glGenOcclusionQueriesNV_ptr(1, &mQueryID);
}

/**
  * Object destructor
  */
GLHardwareOcclusionQuery::~GLHardwareOcclusionQuery() 
{ 
        if (sUseArbQueries && mHasOcclusionSupportARB)
                glDeleteQueriesARB_ptr(1, &mQueryID);  
        else if (!sUseArbQueries && mHasOcclusionSupportNV)
                glDeleteOcclusionQueriesNV_ptr(1, &mQueryID);  
}

//------------------------------------------------------------------
// Occlusion query functions (see base class documentation for this)
//--
void GLHardwareOcclusionQuery::beginOcclusionQuery() 
{ 
        //if (mSkipCounter >= mSkipInterval)  // otherwise no query ever issued if mSkipInterval = 0 !
        //      mSkipCounter = 0; if (mSkipCounter != 0) return;

        if (sUseArbQueries && mHasOcclusionSupportARB)
                        glBeginQueryARB_ptr(GL_SAMPLES_PASSED_ARB, mQueryID);
        else if (!sUseArbQueries && mHasOcclusionSupportNV)
                        glBeginOcclusionQueryNV_ptr(mQueryID);
}
        
void GLHardwareOcclusionQuery::endOcclusionQuery() 
{ 
        //if( mSkipCounter != 0) return;
        if (sUseArbQueries && mHasOcclusionSupportARB)
                        glEndQueryARB_ptr(GL_SAMPLES_PASSED_ARB);
        else if (!sUseArbQueries && mHasOcclusionSupportNV)
                        glEndOcclusionQueryNV_ptr();
//      mSkipCounter++;
                }

bool GLHardwareOcclusionQuery::pullOcclusionQuery( unsigned int* NumOfFragments, const HW_OCCLUSIONQUERY flag  ) 
{
        if (sUseArbQueries && mHasOcclusionSupportARB)
                glGetQueryObjectuivARB_ptr(mQueryID, GL_QUERY_RESULT_ARB, NumOfFragments);
        else if (!sUseArbQueries && mHasOcclusionSupportNV)
glGetOcclusionQueryuivNV_ptr(mQueryID, GL_PIXEL_COUNT_NV, NumOfFragments);
        else
                *NumOfFragments = 100000;               // Fails quietly

        mPixelCount = *NumOfFragments; 
        
        return true;
}

#ifdef GTP_VISIBILITY_MODIFIED_OGRE
//------------------------------------------------------------------
bool GLHardwareOcclusionQuery::pullOcclusionQuery(unsigned int * NumOfFragments, 
                                                                                                  const bool waitForResult, 
                                                                                                  const HW_OCCLUSIONQUERY flag) 
{   
        if (sUseArbQueries && mHasOcclusionSupportARB)  
   {
                int isAvailable = GL_TRUE;

                if (!waitForResult)
                        glGetQueryivARB_ptr(mQueryID, GL_QUERY_RESULT_AVAILABLE_ARB, &isAvailable);
                
                if (isAvailable == GL_TRUE)
                        glGetQueryObjectuivARB_ptr(mQueryID, GL_QUERY_RESULT_ARB, NumOfFragments);

                mPixelCount = *NumOfFragments;

                return isAvailable == GL_TRUE;
   }
        else if (!sUseArbQueries && mHasOcclusionSupportNV)
   {
                unsigned int isAvailable = GL_TRUE;

                if (!waitForResult)
                                glGetOcclusionQueryuivNV_ptr(mQueryID, GL_PIXEL_COUNT_AVAILABLE_NV, &isAvailable);

                if (isAvailable == GL_TRUE)
                                glGetOcclusionQueryuivNV_ptr(mQueryID, GL_PIXEL_COUNT_NV, NumOfFragments);

                mPixelCount = *NumOfFragments; 

                return isAvailable == GL_TRUE;
   }
        
                // In case hardware occlusion isn't supported, every object is set visible.
                *NumOfFragments = 100000;               
                mPixelCount = *NumOfFragments; 

        return GL_TRUE; 
} 

#endif // GTP_VISIBILITY_MODIFIED_OGRE
}