/* -*-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();

        /** Switch on the debug coloring in GLSL (only the first 3 texture/splits showed for visualisation */
        inline void setDebugColorOn() { _debug_color_in_GLSL = true; }

        /** Set the polygon offset osg::Vec2f(factor,unit) */
        inline void setPolygonOffset(const osg::Vec2f& p) { _polgyonOffset = p;_user_polgyonOffset_set=true;}

        /** Get the polygon offset osg::Vec2f(factor,unit) */
        inline const osg::Vec2f& getPolygonOffset() { return _polgyonOffset;}

        /** Set the texture resolution */
        inline void setTextureResolution(unsigned int resolution) { _resolution = resolution; }

        /** Set the max far distance */ 
        inline void setMaxFarDistance(double farDist) { _setMaxFarDistance = farDist; _isSetMaxFarDistance = true; }

        /** Set the factor for moving the virtual camera behind the real camera*/
        inline void setMoveVCamBehindRCamFactor(double distFactor ) { _move_vcam_behind_rcam_factor = distFactor; }

        /** Force to add a cull face front */
        inline void forceFrontCullFace() { _useFrontCullFace = true; }

        /** Set min near distance for splits */ 
        inline void setMinNearDistanceForSplits(double nd){ _split_min_near_dist=nd; }

        /** use linear split (default: linear) */
        inline void useLinearSplit(bool flag) { _linearSplit = flag;}
    
    
    /** 
         light              /  | 
           \             /     |
     min near dist    /        |
      for splits   /           |
              \ /    ¦         |
            ./ \     ¦         |
            |   \    ¦         |
            |    x   ¦         |
            |        ¦         |
            .        |         |
               \       ¦         |
                \    ¦         |
                    \          |
                        \      |
                              \  |
                              
            .<- max far dist. ->.
    */ 
    protected :

        virtual ~ParallelSplitShadowMap() {}

        std::string generateGLSL_FragmentShader_BaseTex(bool debug, unsigned int splitCount);

        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;

        unsigned int _number_of_splits;

        bool _debug_color_in_GLSL;

        osg::Vec2f _polgyonOffset;
        bool _user_polgyonOffset_set;

        unsigned int _resolution;

        double _setMaxFarDistance;
        bool _isSetMaxFarDistance;

        bool _useFrontCullFace;

        double _split_min_near_dist;

        double _move_vcam_behind_rcam_factor;

        bool _linearSplit;

};
}
#endif