/* -*-c++-*- */
/* osgEarth - Geospatial SDK for OpenSceneGraph
 * Copyright 2020 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_AUTOCLIPPLANEHANDLER_H
#define OSGEARTHUTIL_AUTOCLIPPLANEHANDLER_H

#include <osgEarth/Common>
#include <osgEarth/Containers>
#include <osgEarth/Utils>
#include <osgGA/GUIEventHandler>
#include <osgGA/EventVisitor>
#include <osg/Camera>

namespace osgEarth {
    class MapNode;
}

namespace osgEarth { namespace Util
{
    using namespace osgEarth;
    using namespace osgEarth::Util;

    /**
     * A CULL callback that automatically adjusts the calculated near and far clip planes for
     * use in a geocentric map.
     *
     * Usage: add this as a cull callback to a camera, like:
     *
     * osgViewer::Viewer viewer;
     * ...
     * viewer.getCamera()->addCullCallback( new AutoClipPlaneCallback(map) )
     */
    class OSGEARTH_EXPORT AutoClipPlaneCullCallback : public osg::NodeCallback
    {
    public:
        /**
         * Constructs a new auto-clip plane manager corresponding to the parameters
         * in the specified map.
         * @param map Map to take ellipsoid information from; if NULL, use WGS84 values
         */
        AutoClipPlaneCullCallback( MapNode* mapNode =0L );

        virtual ~AutoClipPlaneCullCallback() { }

        /**
         * Sets the minimum near/far ratio to use for this camera. The minimum ratio takes
         * effect when the camera HAE hits zero.
         */
        void setMinNearFarRatio( double value ) { _minNearFarRatio = value; }
        double getMinNearFarRatio() const { return _minNearFarRatio; }

        /**
         * Sets the maximum near/far ratio to use for the camera. The maximum ratio
         * takes effect when the camera HAE hits the Height Threshold.
         */
        void setMaxNearFarRatio( double value ) { _maxNearFarRatio = value; }
        double getMaxNearFarRatio() const { return _maxNearFarRatio; }

        /** 
         * Sets the camera Height (above ellipsoide) at which the near/far ratio
         * hits its maximum value.
         */
        void setHeightThreshold( double value ) { _haeThreshold = value; }
        double getHeightThreshold() const { return _haeThreshold; }

        /**
         * Whether to clamp the the far clipping plane to the approximate
         * visible horizon.
         */
        void setClampFarClipPlane( bool value ) { _autoFarPlaneClamping = value; }
        bool getClampFarClipPlane() const { return _autoFarPlaneClamping; }

    public:
        virtual void operator()( osg::Node* node, osg::NodeVisitor* nv );
        
    protected:
        bool   _active;
        double _minNearFarRatio, _maxNearFarRatio;
        double _haeThreshold;
        double _rp2, _rp;
        bool   _autoFarPlaneClamping;
        osg::observer_ptr<MapNode> _mapNode;
        PerObjectFastMap< osg::Camera*, osg::ref_ptr<osg::CullSettings::ClampProjectionMatrixCallback> > _clampers;
    };

} }

#endif // OSGEARTHUTIL_AUTOCLIPPLANEHANDLER_H