/* -*-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 OSGEARTH_LOCAL_TANGENT_PLANE_H
#define OSGEARTH_LOCAL_TANGENT_PLANE_H 1

#include <osgEarth/Common>
#include <osgEarth/Profile>
#include <osgEarth/TileKey>
#include <osgEarth/Locators>

namespace osgEarth
{
    /**
     * Local Tangent Plane SRS.
     * Please call SpatialReference::createLTP() to construct one of these.
     */
    class TangentPlaneSpatialReference : public SpatialReference
    {
    public:
        TangentPlaneSpatialReference(void* handle, const osg::Vec3d& originLLA);

        /** dtor */
        virtual ~TangentPlaneSpatialReference() { }

        // CUBE is a projected coordinate system.
        virtual bool isGeographic() const { return false; }
        virtual bool isProjected() const { return true; }

        // This SRS uses a WGS84 lat/long SRS under the hood for reprojection. So we need the
        // pre/post transforms to move from LTP to Geodetic and back.
        virtual bool preTransform(double& x, double& y, double& z, void* context) const;
        virtual bool postTransform(double& x, double& y, double& z, void* context) const;

    protected: // SpatialReference overrides

        void _init();
        
        bool _isEquivalentTo( const SpatialReference* srs ) const;

    private:

        osg::Vec3d   _originLLA;
        osg::Matrixd _local2world, _world2local;

    };

}

#endif // OSGEARTH_LOCAL_TANGENT_PLANE_H
