/* -*-c++-*- */
/* osgEarth - Dynamic map generation toolkit for OpenSceneGraph
 * Copyright 2008-2013 Pelican Mapping
 * http://osgearth.org
 *
 * osgEarth 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, see <http://www.gnu.org/licenses/>
 */
#ifndef OSGEARTHUTIL_HSL_COLOR_FILTER
#define OSGEARTHUTIL_HSL_COLOR_FILTER

#include <osgEarthUtil/Common>
#include <osgEarth/ColorFilter>
#include <osg/Uniform>

namespace osgEarth { namespace Util
{
    using namespace osgEarth;

    /**
     * Color filter that adjust the hue/saturation/lightness of a texel.
     */
    class OSGEARTHUTIL_EXPORT HSLColorFilter : public ColorFilter
    {
    public:
        HSLColorFilter();
        HSLColorFilter(const Config& conf);

        virtual ~HSLColorFilter() { }

        /**
         * The hue/saturation/lightness offset, each component is [0..1]
         */
        void setHSLOffset( const osg::Vec3f& hsl );
        osg::Vec3f getHSLOffset() const;

    public: // ColorFilter

        virtual std::string getEntryPointFunctionName() const;

        virtual void install( osg::StateSet* stateSet ) const;

        virtual Config getConfig() const;

    protected:

        unsigned                   _instanceId;
        osg::ref_ptr<osg::Uniform> _hsl;

        void init();
    };

} } // namespace osgEarth::Util

#endif // OSGEARTHUTIL_HSL_COLOR_FILTER
