/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2005 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.
*/

#ifndef OSGPARTICLE_PRECIPITATIONEFFECT
#define OSGPARTICLE_PRECIPITATIONEFFECT

#include <osg/Group>
#include <osg/BoundingBox>
#include <osg/Fog>
#include <osg/Geometry>

#include <osgUtil/CullVisitor>

#include <osgParticle/Export>

namespace osgParticle
{
    class OSGPARTICLE_EXPORT PrecipitationEffect : public osg::Group
    {
    public:
    
        PrecipitationEffect();
        PrecipitationEffect(const PrecipitationEffect& copy, const osg::CopyOp& copyop = osg::CopyOp::SHALLOW_COPY);

        virtual const char* libraryName() const { return "osgParticle"; }
        virtual const char* className() const { return "PrecipitationEffect"; }
        virtual bool isSameKindAs(const osg::Object* obj) const { return dynamic_cast<const PrecipitationEffect*>(obj) != 0; }
        virtual void accept(osg::NodeVisitor& nv) { if (nv.validNodeMask(*this)) { nv.pushOntoNodePath(this); nv.apply(*this); nv.popFromNodePath(); } }

        virtual void traverse(osg::NodeVisitor& nv);
        
        
        /** Set all the parameters to create an rain effect of specified intensity.*/
        void rain(float intensity);
        
        /** Set all the parameters to create an snow effect of specified intensity.*/
        void snow(float intensity);

        
        void setIntensity(float intensity) { _intensity = intensity; }
        float getIntensity() const { return _intensity; }
        
        void setMaximumParticleDensity(float density) { _maximumParticleDensity = density; }
        float setMaximumParticleDensity() const { return _maximumParticleDensity; }

        void setWind(const osg::Vec3& wind) { _wind = wind; }
        const osg::Vec3& getWind() const { return _wind; }
        
        void setPosition(const osg::Vec3& position) { _origin = position; }
        const osg::Vec3& getPosition() const { return _origin; }
        
        void setCellSize(const osg::Vec3& cellSize) { _cellSize = cellSize; }
        const osg::Vec3& getCellSize() const { return _cellSize; }
        
        void setParticleSpeed(float particleSpeed) { _particleSpeed = particleSpeed; }
        float getParticleSpeed() const { return _particleSpeed; }

        void setParticleSize(float particleSize) { _particleSize = particleSize; }
        float getParticleSize() const { return _particleSize; }
        
        void setParticleColor(const osg::Vec4& color) { _particleColor = color; }
        const osg::Vec4& getParticleColor() const { return _particleColor; }
        
        void setNearTransition(float nearTransition) { _nearTransition = nearTransition; }
        float getNearTransition() const { return _nearTransition; }

        void setFarTransition(float farTransition) { _farTransition = farTransition; }
        float getFarTransition() const { return _farTransition; }
        
        void setFog(osg::Fog* fog) { _fog = fog; }
        osg::Fog* getFog() { return _fog.get(); }
        const osg::Fog* getFog() const { return _fog.get(); }
        
        void compileGLObjects(osg::State& state) const;

        void update();

    protected:
    
        virtual ~PrecipitationEffect() {}
        
        void createGeometry(unsigned int numParticles, 
                            osg::Geometry* quad_geometry, 
                            osg::Geometry* line_geometry,
                            osg::Geometry* point_geometry);
                    
        void setUpGeometries(unsigned int numParticles);

        class OSGPARTICLE_EXPORT PrecipitationDrawable : public osg::Drawable
        {
        public:

            PrecipitationDrawable();
            PrecipitationDrawable(const PrecipitationDrawable& copy, const osg::CopyOp& copyop = osg::CopyOp::SHALLOW_COPY);

            META_Object(osgParticle, PrecipitationDrawable);

            virtual bool supports(const osg::PrimitiveFunctor&) const { return false; }
            virtual void accept(osg::PrimitiveFunctor&) const {}
            virtual bool supports(const osg::PrimitiveIndexFunctor&) const { return false; }
            virtual void accept(osg::PrimitiveIndexFunctor&) const {}

            void setRequiresPreviousMatrix(bool flag) { _requiresPreviousMatrix = flag; }
            bool getRequiresPreviousMatrix() const { return _requiresPreviousMatrix; }

            void setGeometry(osg::Geometry* geom) { _geometry = geom; }
            osg::Geometry* getGeometry() { return _geometry.get(); }
            const osg::Geometry* getGeometry() const { return _geometry.get(); }

            virtual void drawImplementation(osg::State& state) const;

            struct Cell
            {
                Cell(int in_i, int in_j, int in_k):
                    i(in_i), j(in_j), k(in_k) {}

                inline bool operator < (const Cell& rhs) const
                {
                    if (i<rhs.i) return true;
                    if (i>rhs.i) return false;
                    if (j<rhs.j) return true;
                    if (j>rhs.j) return false;
                    if (k<rhs.k) return true;
                    if (k>rhs.k) return false;
                    return false;
                }

                int i;
                int j;
                int k;
            };
            
            struct DepthMatrixStartTime
            {
                inline bool operator < (const DepthMatrixStartTime& rhs) const
                {
                    return depth < rhs.depth;
                }
                
                float           depth;
                float           startTime;
                osg::Matrix     modelview;
            };

            typedef std::map< Cell, DepthMatrixStartTime >  CellMatrixMap;

            struct LessFunctor 
            {
                inline bool operator () (const CellMatrixMap::value_type* lhs,const CellMatrixMap::value_type* rhs) const
                {
                    return (*lhs).second<(*rhs).second; 
                }
            };


            CellMatrixMap& getCurrentCellMatrixMap() { return _currentCellMatrixMap; }
            CellMatrixMap& getPreviousCellMatrixMap() { return _previousCellMatrixMap; }

            inline void newFrame()
            {
                _previousCellMatrixMap.swap(_currentCellMatrixMap);
                _currentCellMatrixMap.clear();
            }

        protected:

            virtual ~PrecipitationDrawable() {}

            bool _requiresPreviousMatrix;

            osg::ref_ptr<osg::Geometry> _geometry;

            mutable CellMatrixMap _currentCellMatrixMap;
            mutable CellMatrixMap _previousCellMatrixMap;

        };

        struct PrecipitationDrawableSet
        {
            osg::ref_ptr<PrecipitationDrawable> _quadPrecipitationDrawable;
            osg::ref_ptr<PrecipitationDrawable> _linePrecipitationDrawable;
            osg::ref_ptr<PrecipitationDrawable> _pointPrecipitationDrawable;
        };
        
        void cull(PrecipitationDrawableSet& pds, osgUtil::CullVisitor* cv) const;
        bool build(const osg::Vec3 eyeLocal, int i, int j, int k, float startTime, PrecipitationDrawableSet& pds, osg::Polytope& frustum, osgUtil::CullVisitor* cv) const;

        // parameters
        osg::BoundingBox        _boundingBox;
        float                   _intensity;
        osg::Vec3               _wind;
        float                   _particleSpeed;
        float                   _particleSize;
        osg::Vec4               _particleColor;
        float                   _maximumParticleDensity;
        osg::Vec3               _cellSize;
        float                   _nearTransition;
        float                   _farTransition;
        bool                    _useFarLineSegments;
        osg::ref_ptr<osg::Fog>  _fog;

        typedef std::pair< osg::NodeVisitor*, osg::NodePath > ViewIdenitifier;
        typedef std::map< ViewIdenitifier, PrecipitationDrawableSet >  ViewDrawableMap;

        OpenThreads::Mutex _mutex;
        ViewDrawableMap _viewDrawableMap;
        
        osg::ref_ptr<osg::StateSet>     _precipitationStateSet;
        
        osg::ref_ptr<osg::Geometry> _quadGeometry;
        osg::ref_ptr<osg::StateSet> _quadStateSet;

        osg::ref_ptr<osg::Geometry> _lineGeometry;
        osg::ref_ptr<osg::StateSet> _lineStateSet;

        osg::ref_ptr<osg::Geometry> _pointGeometry;
        osg::ref_ptr<osg::StateSet> _pointStateSet;

        // cache variables.
        float       _period;
        osg::Vec3   _origin;
        osg::Vec3   _du;
        osg::Vec3   _dv;
        osg::Vec3   _dw;
        osg::Vec3   _inverse_du;
        osg::Vec3   _inverse_dv;
        osg::Vec3   _inverse_dw;

    };

}

#endif