source: trunk/VUT/work/ogre_changes/RenderSystems/GL/src/OgreGLHardwareOcclusionQuery.cpp @ 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.
-----------------------------------------------------------------------------
*/

#include "OgreGLHardwareOcclusionQuery.h"
#include "OgreException.h"


namespace Ogre {

/**
  * 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
  */

/**
  * 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.
        //if (glGenQueriesARB_ptr != 0)
        if (glGenOcclusionQueriesNV_ptr != 0)
    {
                mHasOcclusionSupport = true;
        }
        else
        {
                mHasOcclusionSupport = false;
        }

        if(mHasOcclusionSupport)
        {
                //glGenQueriesARB_ptr(1, &mQueryID );   
                glGenOcclusionQueriesNV_ptr(1, &mQueryID);
        }
}

/**
  * Object destructor
  */
GLHardwareOcclusionQuery::~GLHardwareOcclusionQuery() 
{ 
        if( mHasOcclusionSupport )
        {
                //glDeleteQueriesARB_ptr(1, &mQueryID);  
                glDeleteOcclusionQueriesNV_ptr(1, &mQueryID);  
        }       
}

//------------------------------------------------------------------
// Occlusion query functions (see base class documentation for this)
//--
void GLHardwareOcclusionQuery::beginOcclusionQuery() 
{ 
        // Make it fail silently if hardware occlusion isn't supported
        if(mHasOcclusionSupport)
        {
                // Counter starts at 0 again at mSkipInterval 
#ifndef GTP_VISIBILITY_MODIFIED_OGRE
                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)
                {
                        //glBeginQueryARB_ptr(GL_SAMPLES_PASSED_ARB, mQueryID);
                        glBeginOcclusionQueryNV_ptr(mQueryID);
                }
        }
}
        
void GLHardwareOcclusionQuery::endOcclusionQuery() 
{ 
        // Make it fail silently if hardware occlusion isn't supported
        if(mHasOcclusionSupport)
        {
                if( mSkipCounter == 0)
                {
                        //glEndQueryARB_ptr(GL_SAMPLES_PASSED_ARB);
                        glEndOcclusionQueryNV_ptr();
                }

                mSkipCounter++;
        } 
}

//------------------------------------------------------------------
// OpenGL dosn't use the flag paramter.
//------------------------------------------------------------------
bool GLHardwareOcclusionQuery::pullOcclusionQuery( unsigned int* NumOfFragments, const HW_OCCLUSIONQUERY flag  ) 
{
        if( mHasOcclusionSupport )      // Make it fail silently if hardware occlusion isn't supported
        {
                //glGetQueryObjectuivARB_ptr(mQueryID, GL_QUERY_RESULT_ARB, NumOfFragments);
glGetOcclusionQueryuivNV_ptr(mQueryID, GL_PIXEL_COUNT_NV, NumOfFragments);
        }
        else
        {
                *NumOfFragments = 100000;               // Fails quitlly -> every object tested is visable.
        }

        mPixelCount = *NumOfFragments; 
        
        return true;
}

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

                if (mHasOcclusionSupport)       
        {
                if (!waitForResult)
                {
                        // use nv queries rather that arb because they are faster (no flush)
                                //glGetQueryivARB_ptr(mQueryID, GL_QUERY_RESULT_AVAILABLE_ARB, &isAvailable);
                                glGetOcclusionQueryuivNV_ptr(mQueryID, GL_PIXEL_COUNT_AVAILABLE_NV, &isAvailable);
                }

                if (isAvailable == GL_TRUE)
                {
                                //glGetQueryObjectuivARB_ptr(mQueryID, GL_QUERY_RESULT_ARB, NumOfFragments);
                                glGetOcclusionQueryuivNV_ptr(mQueryID, GL_PIXEL_COUNT_NV, NumOfFragments);
                }
        } 
        else
        {
                // In case hardware occlusion isn't supported, every object is set visible.
                *NumOfFragments = 100000;               
        }

                mPixelCount = *NumOfFragments; 

        return isAvailable == GL_TRUE;  
}

#endif // GTP_VIBILITY_MODIFIED_OGRE
}