/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

/*
 * Copyright (C) 2006-2010 - Frictional Games
 *
 * This file is part of HPL1 Engine.
 */

#include "hpl1/engine/impl/OcclusionQueryOGL.h"
#include "hpl1/opengl.h"

#ifdef USE_OPENGL


namespace hpl {

//////////////////////////////////////////////////////////////////////////
// CONSTRUCTORS
//////////////////////////////////////////////////////////////////////////

//-----------------------------------------------------------------------

cOcclusionQueryOGL::cOcclusionQueryOGL() {
	glGenQueries(1, (GLuint *)&mlQueryId);
	mlLastSampleCount = 0;
}

//-----------------------------------------------------------------------

cOcclusionQueryOGL::~cOcclusionQueryOGL() {
	glDeleteQueries(1, (GLuint *)&mlQueryId);
}

//-----------------------------------------------------------------------

//////////////////////////////////////////////////////////////////////////
// PUBLIC METHODS
//////////////////////////////////////////////////////////////////////////

//-----------------------------------------------------------------------

void cOcclusionQueryOGL::Begin() {
	glBeginQuery(GL_SAMPLES_PASSED, mlQueryId);
}

void cOcclusionQueryOGL::End() {
	glEndQuery(GL_SAMPLES_PASSED);
}

bool cOcclusionQueryOGL::FetchResults() {
	int lAvailable = 0;
	glGetQueryObjectiv(mlQueryId, GL_QUERY_RESULT_AVAILABLE, (GLint *)&lAvailable);
	if (lAvailable == 0)
		return false;

	glGetQueryObjectiv(mlQueryId, GL_QUERY_RESULT, (GLint *)&mlLastSampleCount);
	return true;
}

unsigned int cOcclusionQueryOGL::GetSampleCount() {
	return mlLastSampleCount;
}

//-----------------------------------------------------------------------
} // namespace hpl

#endif // USE_OPENGL
