/* -*-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.
*/
//osgParticle - Copyright (C) 2002 Marco Jez

#ifndef OSGPARTICLE_PARTICLE
#define OSGPARTICLE_PARTICLE 1

#include <osgParticle/Export>
#include <osgParticle/Interpolator>
#include <osgParticle/range>

#include <osg/ref_ptr>
#include <osg/Vec3>
#include <osg/Vec4>
#include <osg/Matrix>
#include <osg/GL>

namespace osgParticle
{

    // forward declare so we can reference it
    class ParticleSystem;

    /**    Implementation of a <B>particle</B>.
        Objects of this class are particles, they have some graphical properties
        and some physical properties. Particles are created by emitters and then placed
        into Particle Systems, where they live and get updated at each frame.
        Particles can either live forever (lifeTime < 0), or die after a specified
        time (lifeTime >= 0). For each property which is defined as a range of values, a
        "current" value will be evaluated at each frame by interpolating the <I>min</I>
        and <I>max</I> values so that <I>curr_value = min</I> when <I>t == 0</I>, and 
        <I>curr_value = max</I> when <I>t == lifeTime</I>.
        You may customize the interpolator objects to achieve any kind of transition.
        If you want the particle to live forever, set its lifetime to any value <= 0;
        in that case, no interpolation is done to compute real-time properties, and only
        minimum values are used.
    */
    class OSGPARTICLE_EXPORT Particle {
    public:
        
        enum
        {
            INVALID_INDEX = -1
        };

        /**
         Shape of particles.
         NOTE: the LINE shape should be used in conjunction with FIXED alignment mode (see ParticleSystem).
        */
        enum Shape {
            POINT,            // uses GL_POINTS as primitive
            QUAD,            // uses GL_QUADS as primitive
            QUAD_TRIANGLESTRIP,    // uses GL_TRI_angleSTRIP as primitive, but each particle needs a glBegin/glEnd pair
            HEXAGON,            // may save some filling time, but uses more triangles
            LINE                // uses GL_LINES to draw line segments that point to the direction of motion            
        };
        
        Particle();

        /// Get the shape of the particle.
        inline Shape getShape() const;
        
        /// Set the shape of the particle.
        inline void setShape(Shape s);

        /// Get whether the particle is still alive.
        inline bool isAlive() const;
        
        /// Get the life time of the particle (in seconds).
        inline double getLifeTime() const;
        
        /// Get the age of the particle (in seconds).
        inline double getAge() const;
        
        /// Get the minimum and maximum values for polygon size.
        inline const rangef& getSizeRange() const;
        
        /// Get the minimum and maximum values for alpha.
        inline const rangef& getAlphaRange() const;
        
        /// Get the minimum and maximum values for color.
        inline const rangev4& getColorRange() const;
        
        /// Get the interpolator for computing the size of polygons.
        inline const Interpolator* getSizeInterpolator() const;
        
        /// Get the interpolator for computing alpha values.
        inline const Interpolator* getAlphaInterpolator() const;
        
        /// Get the interpolator for computing color values.
        inline const Interpolator* getColorInterpolator() const;

        /** Get the physical radius of the particle.
            For built-in operators to work correctly, lengths must be expressed in meters.
        */
        inline float getRadius() const;
        
        /** Get the mass of the particle.
            For built-in operators to work correctly, remember that the mass is expressed in kg.
        */
        inline float getMass() const;
        
        /// Get <CODE>1 / getMass()</CODE>.
        inline float getMassInv() const;
        
        /// Get the position vector.
        inline const osg::Vec3& getPosition() const;
        
        /**    Get the velocity vector.
            For built-in operators to work correctly, remember that velocity components are expressed
            in meters per second.
        */
        inline const osg::Vec3& getVelocity() const;        
        
        /// Get the previous position (the position before last update).
        inline const osg::Vec3& getPreviousPosition() const;

        /// Get the angle vector.
        inline const osg::Vec3& getAngle() const;
        
        /// Get the rotational velocity vector.
        inline const osg::Vec3& getAngularVelocity() const;
        
        /// Get the previous angle vector.
        inline const osg::Vec3& getPreviousAngle() const;
        
        /// Get the current color
        inline const osg::Vec4& getCurrentColor() const { return _current_color; }

        /// Get the current alpha
        inline float getCurrentAlpha() const { return _current_alpha; }
        
        /// Get the s texture coordinate of the bottom left of the particle
        inline const float getSTexCoord() const { return _s_coord; }

        /// Get the t texture coordinate of the bottom left of the particle
        inline float getTCoord() const { return _t_coord; }

        /// Get width of texture tile
        inline int getTileS() const;
        
        /// Get height of texture tile
        inline int getTileT() const;
        
        /// Get number of texture tiles
        inline int getNumTiles() const { return _num_tile; }
        
        /** Kill the particle on next update
            NOTE: after calling this function, the <CODE>isAlive()</CODE> method will still 
            return true until the particle is updated again.
        */
        inline void kill();
        
        /// Set the life time of the particle.
        inline void setLifeTime(double t);
        
        /// Set the minimum and maximum values for polygon size.
        inline void setSizeRange(const rangef& r);
        
        /// Set the minimum and maximum values for alpha.
        inline void setAlphaRange(const rangef& r);
        
        /// Set the minimum and maximum values for color.
        inline void setColorRange(const rangev4& r);
        
        /// Set the interpolator for computing size values.
        inline void setSizeInterpolator(Interpolator* ri);
        
        /// Set the interpolator for computing alpha values.        
        inline void setAlphaInterpolator(Interpolator* ai);
        
        /// Set the interpolator for computing color values.
        inline void setColorInterpolator(Interpolator* ci);

        /** Set the physical radius of the particle.
            For built-in operators to work correctly, lengths must be expressed in meters.
        */
        inline void setRadius(float r);
        
        /** Set the mass of the particle.
            For built-in operators to work correctly, remember that the mass is expressed in kg.
        */
        inline void setMass(float m);
        
        /// Set the position vector.        
        inline void setPosition(const osg::Vec3& p);
        
        /**    Set the velocity vector.
            For built-in operators to work correctly, remember that velocity components are expressed
            in meters per second.
        */
        inline void setVelocity(const osg::Vec3& v);
        
        /// Add a vector to the velocity vector.
        inline void addVelocity(const osg::Vec3& dv);
        
        /// Transform position and velocity vectors by a matrix.
        inline void transformPositionVelocity(const osg::Matrix& xform);

        /// Transform position and velocity vectors by a combination of two matrices
        void transformPositionVelocity(const osg::Matrix& xform1, const osg::Matrix& xform2, float r);

        /// Set the angle vector.
        inline void setAngle(const osg::Vec3& a);
        
        /**
          Set the angular velocity vector. 
          Components x, y and z are angles of rotation around the respective axis (in radians).
        */
        inline void setAngularVelocity(const osg::Vec3& v);
        
        /// Add a vector to the angular velocity vector.
        inline void addAngularVelocity(const osg::Vec3& dv);
        
        /// Transform angle and angularVelocity vectors by a matrix.
        inline void transformAngleVelocity(const osg::Matrix& xform);
        
        /**    Update the particle (don't call this method manually).
            This method is called automatically by <CODE>ParticleSystem::update()</CODE>; it
            updates the graphical properties of the particle for the current time,
            checks whether the particle is still alive, and then updates its position
            by computing <I>P = P + V * dt</I> (where <I>P</I> is the position and <I>V</I> is the velocity).
        */
        bool update(double dt);

        /// Perform some pre-rendering tasks. Called automatically by particle systems.
        inline void beginRender() const;
        
        /// Render the particle. Called automatically by particle systems.
        void render(const osg::Vec3& xpos, const osg::Vec3& px, const osg::Vec3& py, float scale = 1.0f) const;
        
        /// Perform some post-rendering tasks. Called automatically by particle systems.
        inline void endRender() const;
        
        /// Get the current (interpolated) polygon size. Valid only after the first call to update().
        inline float getCurrentSize() const;
        
        /// Specify how the particle texture is tiled
        inline void setTextureTile(int sTile, int tTile, int numTiles = 0);

        /// Set the previous particle
        inline void setPreviousParticle(int previous) { _previousParticle = previous; }

        /// Get the previous particle
        inline int getPreviousParticle() const { return _previousParticle; }

        /// Set the next particle
        inline void setNextParticle(int next) { _nextParticle = next; }

        /// Get the const next particle
        inline int getNextParticle() const { return _nextParticle; }

        /// Method for initializing a particles texture coords as part of a connected particle system.
        void setUpTexCoordsAsPartOfConnectedParticleSystem(ParticleSystem* ps);

    protected:
    
        Shape _shape;

        rangef _sr;
        rangef _ar;
        rangev4 _cr;

        osg::ref_ptr<Interpolator> _si;
        osg::ref_ptr<Interpolator> _ai;
        osg::ref_ptr<Interpolator> _ci;

        bool _alive;
        bool _mustdie;
        double _lifeTime;

        float _radius;
        float _mass;
        float _massinv;
        osg::Vec3 _prev_pos;
        osg::Vec3 _position;
        osg::Vec3 _velocity;

        osg::Vec3 _prev_angle;
        osg::Vec3 _angle;
        osg::Vec3 _angul_arvel;

        double _t0;        

        float _current_size;
        float _current_alpha;
        osg::Vec4 _current_color;
        
        float _s_tile;
        float _t_tile;
        int _num_tile;
        int _cur_tile;
        float _s_coord;
        float _t_coord;
        
        // previous and next Particles are only used in ConnectedParticleSystems
        int _previousParticle;
        int _nextParticle;
    };

    // INLINE FUNCTIONS

    inline Particle::Shape Particle::getShape() const
    {
        return _shape;
    }

    inline void Particle::setShape(Shape s)
    {
        _shape = s;
    }

    inline bool Particle::isAlive() const
    {
        return _alive;
    }

    inline double Particle::getLifeTime() const
    {
        return _lifeTime;
    }
    
    inline double Particle::getAge() const
    {
        return _t0;
    }
    
    inline float Particle::getRadius() const
    {
        return _radius;
    }
    
    inline void Particle::setRadius(float r)
    {
        _radius = r;
    }

    inline const rangef& Particle::getSizeRange() const
    {
        return _sr;
    }

    inline const rangef& Particle::getAlphaRange() const
    {
        return _ar;
    }

    inline const rangev4& Particle::getColorRange() const
    {
        return _cr;
    }

    inline const Interpolator* Particle::getSizeInterpolator() const
    {
        return _si.get();
    }

    inline const Interpolator* Particle::getAlphaInterpolator() const
    {
        return _ai.get();
    }

    inline const Interpolator* Particle::getColorInterpolator() const
    {
        return _ci.get();
    }

    inline const osg::Vec3& Particle::getPosition() const
    {
        return _position;
    }

    inline const osg::Vec3& Particle::getVelocity() const
    {
        return _velocity;
    }
    
    inline const osg::Vec3& Particle::getPreviousPosition() const
    {
        return _prev_pos;
    }

    inline const osg::Vec3& Particle::getAngle() const
    {
        return _angle;
    }
    
    inline const osg::Vec3& Particle::getAngularVelocity() const
    {
        return _angul_arvel;
    }
    
    inline const osg::Vec3& Particle::getPreviousAngle() const
    {
        return _prev_angle;
    }
    
    inline int Particle::getTileS() const
    {
        return (_s_tile>0.0f) ? static_cast<int>(1.0f / _s_tile) : 1;
    }

    inline int Particle::getTileT() const
    {
        return (_t_tile>0.0f) ? static_cast<int>(1.0f / _t_tile) : 1;
    }
    
    inline void Particle::kill()
    {
        _mustdie = true;
    }

    inline void Particle::setLifeTime(double t)
    {
        _lifeTime = t;
    }

    inline void Particle::setSizeRange(const rangef& r)
    {
        _sr = r;
    }

    inline void Particle::setAlphaRange(const rangef& r)
    {
        _ar = r;
    }

    inline void Particle::setColorRange(const rangev4& r)
    {
        _cr = r;
    }

    inline void Particle::setSizeInterpolator(Interpolator* ri)
    {
        _si = ri;
    }

    inline void Particle::setAlphaInterpolator(Interpolator* ai)
    {
        _ai = ai;
    }

    inline void Particle::setColorInterpolator(Interpolator* ci)
    {
        _ci = ci;
    }

    inline void Particle::setPosition(const osg::Vec3& p)
    {
        _position = p;
    }

    inline void Particle::setVelocity(const osg::Vec3& v)
    {
        _velocity = v;
    }

    inline void Particle::addVelocity(const osg::Vec3& dv)
    {
        _velocity += dv;
    }

    inline void Particle::transformPositionVelocity(const osg::Matrix& xform)
    {
        _position = xform.preMult(_position);
        _velocity = osg::Matrix::transform3x3(_velocity, xform);
    }
    
    inline void Particle::transformPositionVelocity(const osg::Matrix& xform1, const osg::Matrix& xform2, float r)
    {
        osg::Vec3 position1 = xform1.preMult(_position);
        osg::Vec3 velocity1 = osg::Matrix::transform3x3(_velocity, xform1);
        osg::Vec3 position2 = xform2.preMult(_position);
        osg::Vec3 velocity2 = osg::Matrix::transform3x3(_velocity, xform2);
        float one_minus_r = 1.0f-r;
        _position = position1*r + position2*one_minus_r;
        _velocity = velocity1*r + velocity2*one_minus_r;
    }
    
    inline void Particle::setAngle(const osg::Vec3& a)
    {
        _angle = a;
    }
    
    inline void Particle::setAngularVelocity(const osg::Vec3& v)
    {
        _angul_arvel = v;
    }
    
    inline void Particle::addAngularVelocity(const osg::Vec3& dv)
    {
        _angul_arvel += dv;
    }
    
    inline void Particle::transformAngleVelocity(const osg::Matrix& xform)
    {
        // this should be optimized!
        
        osg::Vec3 a1 = _angle + _angul_arvel;
        
        _angle = xform.preMult(_angle);
        a1 = xform.preMult(a1);
        
        _angul_arvel = a1 - _angle;
    }
            
    inline float Particle::getMass() const
    {
        return _mass;
    }
    
    inline float Particle::getMassInv() const
    {
        return _massinv;
    }
    
    inline void Particle::setMass(float m)
    {
        _mass = m;
        _massinv = 1 / m;
    }
    
    inline void Particle::beginRender() const
    {
        switch (_shape)
        {
        case POINT:
            glBegin(GL_POINTS);
            break;
        case QUAD:
            glBegin(GL_QUADS);
            break;
        case LINE:
            glBegin(GL_LINES);
            break;
        default: ;
        }
    }
    
    inline void Particle::endRender() const
    {
        switch (_shape)
        {        
        case POINT:
        case QUAD:
        case LINE:
            glEnd();
            break;
        default: ;
        }
    }
    
    inline float Particle::getCurrentSize() const
    {
        return _current_size;
    }
    
    inline void Particle::setTextureTile(int sTile, int tTile, int numTiles)
    {
        _s_tile = (sTile>0) ? 1.0f / static_cast<float>(sTile) : 1.0f;
        _t_tile = (tTile>0) ? 1.0f / static_cast<float>(tTile) : 1.0f;
        if (numTiles <= 0)
        {
            _num_tile = sTile * tTile;
        }
        else
        {
            _num_tile = numTiles;
        }
    }


}

#endif