ParticleSystem.hpp

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//
// Thor C++ Library
// Copyright (c) 2011-2016 Jan Haller
//
// This software is provided 'as-is', without any express or implied
// warranty. In no event will the authors be held liable for any damages
// arising from the use of this software.
//
// Permission is granted to anyone to use this software for any purpose,
// including commercial applications, and to alter it and redistribute it
// freely, subject to the following restrictions:
//
// 1. The origin of this software must not be misrepresented; you must not
//    claim that you wrote the original software. If you use this software
//    in a product, an acknowledgment in the product documentation would be
//    appreciated but is not required.
//
// 2. Altered source versions must be plainly marked as such, and must not be
//    misrepresented as being the original software.
//
// 3. This notice may not be removed or altered from any source distribution.
//


#ifndef THOR_PARTICLESYSTEM_HPP
#define THOR_PARTICLESYSTEM_HPP

#include <Thor/Particles/Particle.hpp>
#include <Thor/Particles/EmissionInterface.hpp>
#include <Thor/Input/Connection.hpp>
#include <Thor/Config.hpp>

#include <SFML/System/NonCopyable.hpp>
#include <SFML/System/Vector2.hpp>
#include <SFML/Graphics/Rect.hpp>
#include <SFML/Graphics/Drawable.hpp>
#include <SFML/Graphics/VertexArray.hpp>

#include <vector>
#include <utility>
#include <functional>
#include <memory>
#include <array>


namespace sf
{

    class RenderWindow;
    class Image;
    class Texture;

} // namespace sf


namespace thor
{
namespace detail
{
    class AbstractConnectionImpl;
}


class THOR_API ParticleSystem : public sf::Drawable, private sf::NonCopyable, private EmissionInterface
{
    // ---------------------------------------------------------------------------------------------------------------------------
    // Private types
    private:
        // Type to store affector or emitter + time until removal + id for removal
        template <typename Signature>
        struct Function
        {
            Function(std::function<Signature> function, sf::Time timeUntilRemoval)
            : function(std::move(function))
            , timeUntilRemoval(timeUntilRemoval)
            , id(nextId())
            , tracker()
            {
            }

            static unsigned int nextId()
            {
                static unsigned int next = 0;
                return next++;
            }

            std::function<Signature>                        function;
            sf::Time                                        timeUntilRemoval;
            unsigned int                                    id;
            std::shared_ptr<detail::AbstractConnectionImpl> tracker;
        };

        // Vertex quads, used to cache texture rectangles
        typedef std::array<sf::Vertex, 4>                   Quad;

        // Function typedefs
        typedef Function<void(Particle&, sf::Time)>         Affector;
        typedef Function<void(EmissionInterface&, sf::Time)>    Emitter;

        // Container typedefs
        typedef std::vector<Particle>                       ParticleContainer;
        typedef std::vector<Affector>                       AffectorContainer;
        typedef std::vector<Emitter>                        EmitterContainer;


    // ---------------------------------------------------------------------------------------------------------------------------
    // Public member functions
    public:
                                    ParticleSystem();

                                    ParticleSystem(ParticleSystem&& source);

        ParticleSystem&             operator= (ParticleSystem&& source);

        void                        setTexture(const sf::Texture& texture);

        unsigned int                addTextureRect(const sf::IntRect& textureRect);

        Connection                  addAffector(std::function<void(Particle&, sf::Time)> affector);

        Connection                  addAffector(std::function<void(Particle&, sf::Time)> affector, sf::Time timeUntilRemoval);

        void                        clearAffectors();

        Connection                  addEmitter(std::function<void(EmissionInterface&, sf::Time)> emitter);

        Connection                  addEmitter(std::function<void(EmissionInterface&, sf::Time)> emitter, sf::Time timeUntilRemoval);

        void                        clearEmitters();

        void                        update(sf::Time dt);

        void                        clearParticles();


    // ---------------------------------------------------------------------------------------------------------------------------
    // Private member functions
    private:
        virtual void                draw(sf::RenderTarget& target, sf::RenderStates states) const;

        virtual void                emitParticle(const Particle& particle);

        // Updates a single particle.
        void                        updateParticle(Particle& particle, sf::Time dt);

        // Recomputes the vertex array.
        void                        computeVertices() const;

        // Recomputes the cached rectangles (position and texCoords quads)
        void                        computeQuads() const;
        void                        computeQuad(Quad& quad, const sf::IntRect& textureRect) const;


    // ---------------------------------------------------------------------------------------------------------------------------
    // Private variables
    private:
        ParticleContainer           mParticles;
        AffectorContainer           mAffectors;
        EmitterContainer            mEmitters;

        const sf::Texture*          mTexture;
        std::vector<sf::IntRect>    mTextureRects;

        mutable sf::VertexArray     mVertices;
        mutable bool                mNeedsVertexUpdate;
        mutable std::vector<Quad>   mQuads;
        mutable bool                mNeedsQuadUpdate;
};


} // namespace thor

#endif // THOR_PARTICLESYSTEM_HPP