/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2006 Robert Osfield 
 *
 * This library is open source and may be redistributed and/or modified under  
 * the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or 
 * (at your option) any later version.  The full license is in LICENSE file
 * included with this distribution, and on the openscenegraph.org website.
 * 
 * This library 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 
 * OpenSceneGraph Public License for more details.
*/

/* ParallelSplitShadowMap written by Adrian Egli */

#ifndef OSGSHADOW_ParallelSplitShadowMap 
#define OSGSHADOW_ParallelSplitShadowMap 1

#include <osg/Camera>
#include <osg/Material>

#include <osgShadow/ShadowTechnique>
 
namespace osgShadow {
class OSGSHADOW_EXPORT ParallelSplitShadowMap :  public ShadowTechnique 
{
    public:
        ParallelSplitShadowMap(osg::Geode** debugGroup=NULL, int icountplanes=3);

        ParallelSplitShadowMap(const ParallelSplitShadowMap& es, const osg::CopyOp& copyop=osg::CopyOp::SHALLOW_COPY);
        
        META_Object(osgShadow, ParallelSplitShadowMap);


        /** initialize the ShadowedScene and local cached data structures.*/
        virtual void init();

        /** run the update traversal of the ShadowedScene and update any loca chached data structures.*/
        virtual void update(osg::NodeVisitor& nv);

        /** run the cull traversal of the ShadowedScene and set up the rendering for this ShadowTechnique.*/
        virtual void cull(osgUtil::CullVisitor& cv);

        /** Clean scene graph from any shadow technique specific nodes, state and drawables.*/
        virtual void cleanSceneGraph();

    protected :

        virtual ~ParallelSplitShadowMap() {}

        
        struct PSSMShadowSplitTexture {
            // RTT
            osg::ref_ptr<osg::Camera>       _camera;
            osg::ref_ptr<osg::TexGen>       _texgen;
            osg::ref_ptr<osg::Texture2D>    _texture;
            osg::ref_ptr<osg::StateSet>     _stateset;
            unsigned int                    _textureUnit;
            osg::Vec2d                      _ambientBias;


            osg::ref_ptr<osg::Camera>       _debug_camera;
            osg::ref_ptr<osg::Texture2D>    _debug_texture;
            osg::ref_ptr<osg::StateSet>     _debug_stateset;
            unsigned int                    _debug_textureUnit;


            
            // Light (SUN)
            osg::Vec3d                        _lightCameraSource;
            osg::Vec3d                        _lightCameraTarget;
            osg::Vec3d                        _frustumSplitCenter;
            osg::Vec3d                        _lightDirection;
            double                            _lightNear;
            double                            _lightFar;

            osg::Matrix                        _cameraView;
            osg::Matrix                        _cameraProj;

            unsigned int                    _splitID;
            unsigned int                    _resolution;

            osg::Uniform*                    _farDistanceSplit;

        };
        typedef std::map<unsigned int,PSSMShadowSplitTexture> PSSMShadowSplitTextureMap;
        PSSMShadowSplitTextureMap _PSSMShadowSplitTextureMap;


    private:
        void calculateFrustumCorners(PSSMShadowSplitTexture &pssmShadowSplitTexture,osg::Vec3d *frustumCorners);
        void calculateLightInitalPosition(PSSMShadowSplitTexture &pssmShadowSplitTexture,osg::Vec3d *frustumCorners);
        void calculateLightNearFarFormFrustum(PSSMShadowSplitTexture &pssmShadowSplitTexture,osg::Vec3d *frustumCorners);
        void calculateLightViewProjectionFormFrustum(PSSMShadowSplitTexture &pssmShadowSplitTexture,osg::Vec3d *frustumCorners);

        osg::Geode** _displayTexturesGroupingNode;

        unsigned int _textureUnitOffset;

};
}
#endif