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

#ifndef OSGPARTICLE_PARTICLESYSTEM
#define OSGPARTICLE_PARTICLESYSTEM 1

#include <osgParticle/Export>
#include <osgParticle/Particle>

#include <vector>
#include <stack>
#include <algorithm>
#include <string>

#include <osg/Object>
#include <osg/Drawable>
#include <osg/CopyOp>
#include <osg/State>
#include <osg/Vec3>
#include <osg/BoundingBox>

namespace osgParticle
{

    /** The heart of this class library; its purpose is to hold a set of particles and manage particle creation, update, rendering and destruction.
      * You can add this drawable to any Geode as you usually do with other
      * Drawable classes. Each instance of ParticleSystem is a separate set of
      * particles; it provides the interface for creating particles and iterating
      * through them (see the Emitter and Program classes).
    */
    class OSGPARTICLE_EXPORT ParticleSystem: public osg::Drawable {
    public:
    
        enum Alignment {
            BILLBOARD,
            FIXED
        };

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

        META_Object(osgParticle, ParticleSystem);
        
        /// Get the alignment type of particles.
        inline Alignment getParticleAlignment() const;
        
        /// Set the alignment type of particles.
        inline void setParticleAlignment(Alignment a);
        
        /// Get the X-axis alignment vector.
        inline const osg::Vec3& getAlignVectorX() const;
        
        /// Set the X-axis alignment vector.
        inline void setAlignVectorX(const osg::Vec3& v);

        /// Get the Y-axis alignment vector.
        inline const osg::Vec3& getAlignVectorY() const;
        
        /// Set the Y-axis alignment vector.
        inline void setAlignVectorY(const osg::Vec3& v);
        
        /// Set the alignment vectors.
        inline void setAlignVectors(const osg::Vec3& X, const osg::Vec3& Y);

        /// Get the default bounding box
        inline const osg::BoundingBox& getDefaultBoundingBox() const;        
        
        /**    Set the default bounding box.
            The default bounding box is used when a real bounding box cannot be computed, for example
            because no particles has been updated yet.
        */
        inline void setDefaultBoundingBox(const osg::BoundingBox& bbox);

        /// Get the double pass rendering flag.
        inline bool getDoublePassRendering() const;
        
        /** Set the double pass rendering flag.
            Double pass rendering avoids overdraw problems between particle systems
            and other opaque objects. If you can render all the particle systems after
            the opaque objects, then double pass is not necessary and can be turned off (best choice).
            If you set the default attributes with setDefaultAttributes, then the particle
            system will fall into a transparent bin.
        */
        inline void setDoublePassRendering(bool v);
        
        /// Return true if the particle system is frozen.
        inline bool isFrozen() const;
        
        /**    Set or reset the <I>frozen</I> state.
            When the particle system is frozen, emitters and programs won't do anything on it.
        */
        inline void setFrozen(bool v);

        /// Get the number of allocated particles (alive + dead).
        inline int numParticles() const;
        
        /// Get the number of dead particles.
        inline int numDeadParticles() const;

        /// Get whether all particles are dead        
        inline bool areAllParticlesDead() const { return numDeadParticles()==numParticles(); }
        
        /// Get a pointer to the i-th particle.
        inline Particle* getParticle(int i);
        
        /// Get a const pointer to the i-th particle.
        inline const Particle* getParticle(int i) const;
        
        /// Create a new particle from the specified template (or the default one if <CODE>ptemplate</CODE> is null).
        inline virtual Particle* createParticle(const Particle* ptemplate);
        
        /// Destroy the i-th particle.
        inline virtual void destroyParticle(int i);
        
        /// Reuse the i-th particle.
        inline virtual void reuseParticle(int i) { _deadparts.push(&(_particles[i])); }

        /// Get the last frame number.
        inline int getLastFrameNumber() const;

        /// Get a reference to the default particle template.
        inline Particle& getDefaultParticleTemplate();
        
        /// Get a const reference to the default particle template.
        inline const Particle& getDefaultParticleTemplate() const;

        /// Set the default particle template (particle is copied).
        inline void setDefaultParticleTemplate(const Particle& p);
        
        /// Get whether the particle system can freeze when culled
        inline bool getFreezeOnCull() const;
        
        /// Set whether the particle system can freeze when culled (default is true)
        inline void setFreezeOnCull(bool v);
        
        /** A useful method to set the most common <CODE>StateAttribute</CODE>'s in one call.
            If <CODE>texturefile</CODE> is empty, then texturing is turned off.
        */
        void setDefaultAttributes(const std::string& texturefile = "", bool emissive_particles = true, bool lighting = false, int texture_unit = 0);
        
        /// (<B>EXPERIMENTAL</B>) Get the level of detail.
        inline int getLevelOfDetail() const;
        
        /** (<B>EXPERIMENTAL</B>) Set the level of detail. The total number of particles is divided by the detail value to
            get the actual number of particles to be drawn. This value must be greater than zero.
        */
        inline void setLevelOfDetail(int v);

        /// Update the particles. Don't call this directly, use a <CODE>ParticleSystemUpdater</CODE> instead.
        virtual void update(double dt);

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

        virtual osg::BoundingBox computeBound() const;

    protected:

        virtual ~ParticleSystem();

        ParticleSystem& operator=(const ParticleSystem&) { return *this; }

        inline void update_bounds(const osg::Vec3& p, float r);
        void single_pass_render(osg::State& state, const osg::Matrix& modelview) const;

        typedef std::vector<Particle> Particle_vector;
        typedef std::stack<Particle*> Death_stack;

        Particle_vector _particles;
        Death_stack _deadparts;
        
        osg::BoundingBox _def_bbox;
        
        Alignment _alignment;
        osg::Vec3 _align_X_axis;
        osg::Vec3 _align_Y_axis;

        bool _doublepass;
        bool _frozen;

        osg::Vec3 _bmin;
        osg::Vec3 _bmax;

        bool _reset_bounds_flag;
        bool _bounds_computed;

        Particle _def_ptemp;
        mutable int _last_frame;
        bool _freeze_on_cull;
        
        int _detail;
        mutable int _draw_count;
        
    };
    
    // INLINE FUNCTIONS
    
    inline ParticleSystem::Alignment ParticleSystem::getParticleAlignment() const
    {
        return _alignment;
    }
    
    inline void ParticleSystem::setParticleAlignment(Alignment a)
    {
        _alignment = a;
    }
    
    inline const osg::Vec3& ParticleSystem::getAlignVectorX() const
    {
        return _align_X_axis;
    }
    
    inline void ParticleSystem::setAlignVectorX(const osg::Vec3& v)
    {
        _align_X_axis = v;
    }

    inline const osg::Vec3& ParticleSystem::getAlignVectorY() const
    {
        return _align_Y_axis;
    }
    
    inline void ParticleSystem::setAlignVectorY(const osg::Vec3& v)
    {
        _align_Y_axis = v;
    }
    
    inline void ParticleSystem::setAlignVectors(const osg::Vec3& X, const osg::Vec3& Y)
    {
        _align_X_axis = X;
        _align_Y_axis = Y;
    }

    inline bool ParticleSystem::isFrozen() const
    {
        return _frozen;
    }
    
    inline void ParticleSystem::setFrozen(bool v)
    {
        _frozen = v;
    }
    
    inline const osg::BoundingBox& ParticleSystem::getDefaultBoundingBox() const
    {
        return _def_bbox;
    }
    
    inline void ParticleSystem::setDefaultBoundingBox(const osg::BoundingBox& bbox)
    {
        _def_bbox = bbox;
    }

    inline bool ParticleSystem::getDoublePassRendering() const
    {
        return _doublepass;
    }

    inline void ParticleSystem::setDoublePassRendering(bool v)
    {
        _doublepass = v;
    }

    inline int ParticleSystem::numParticles() const
    {
        return static_cast<int>(_particles.size());
    }

    inline int ParticleSystem::numDeadParticles() const
    {
        return static_cast<int>(_deadparts.size());
    }

    inline Particle* ParticleSystem::getParticle(int i)
    {
        return &_particles[i];
    }

    inline const Particle* ParticleSystem::getParticle(int i) const
    {
        return &_particles[i];
    }

    inline void ParticleSystem::destroyParticle(int i)
    {
        _particles[i].kill();
    }
    
    inline int ParticleSystem::getLastFrameNumber() const
    {
        return _last_frame;
    }

    inline void ParticleSystem::update_bounds(const osg::Vec3& p, float r)
    {
        if (_reset_bounds_flag) {
            _reset_bounds_flag = false;
            _bmin = p - osg::Vec3(r,r,r);
            _bmax = p + osg::Vec3(r,r,r);
        } else {
            if (p.x() - r < _bmin.x()) _bmin.x() = p.x() - r;
            if (p.y() - r < _bmin.y()) _bmin.y() = p.y() - r;
            if (p.z() - r < _bmin.z()) _bmin.z() = p.z() - r;
            if (p.x() + r > _bmax.x()) _bmax.x() = p.x() + r;
            if (p.y() + r > _bmax.y()) _bmax.y() = p.y() + r;
            if (p.z() + r > _bmax.z()) _bmax.z() = p.z() + r;
        }
        if (!_bounds_computed) 
            _bounds_computed = true;
    }

    inline Particle& ParticleSystem::getDefaultParticleTemplate()
    {
        return _def_ptemp;
    }

    inline const Particle& ParticleSystem::getDefaultParticleTemplate() const
    {
        return _def_ptemp;
    }

    inline void ParticleSystem::setDefaultParticleTemplate(const Particle& p)
    {
        _def_ptemp = p;
    }
    
    inline bool ParticleSystem::getFreezeOnCull() const
    {
        return _freeze_on_cull;
    }
    
    inline void ParticleSystem::setFreezeOnCull(bool v)
    {
        _freeze_on_cull = v;
    }
    
    inline int ParticleSystem::getLevelOfDetail() const
    {
        return _detail;
    }
    
    inline void ParticleSystem::setLevelOfDetail(int v)
    {
        if (v < 1) v = 1;
        _detail = v;
    }
    
    // I'm not sure this function should be inlined... 
    
    inline Particle* ParticleSystem::createParticle(const Particle* ptemplate)
    {
        // is there any dead particle?
        if (!_deadparts.empty()) {

            // retrieve a pointer to the last dead particle
            Particle* P = _deadparts.top();

            // create a new (alive) particle in the same place
            *P = Particle(ptemplate? *ptemplate: _def_ptemp);

            // remove the pointer from the death stack
            _deadparts.pop();
            return P;

        } else {

            // add a new particle to the vector
            _particles.push_back(Particle(ptemplate? *ptemplate: _def_ptemp));
            return &_particles.back();
        }
    }


}

#endif