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C-/C++-Quelltext

struct particle
{
    enum Type
    {
        fire,
        typeCount
    };

    sf::Vector2f position;
    sf::Time leftLifetime;
};


class particleSystem : public sf::Drawable
{
public:
    particleSystem(particle::Type mType);

    void update(sf::Time timePerFrame);
    void addParticle(sf::Vector2f position);
    

private:
    virtual void draw(sf::RenderTarget& target, sf::RenderStates states) const override;
    void updateVertices() const;
    void addVertex(sf::Vector2f worldPos, sf::Vector2f texCoords, float alphaValue) const;


    particle::Type mType;
    sf::Time particleLifetime;
    const sf::Texture* mTexture;

    std::deque<particle> particles;
    mutable sf::VertexArray vertices;
};

C-/C++-Quelltext

particleSystem::particleSystem(particle::Type mType)
    :
    mType(mType),
    mTexture(nullptr),
    vertices(sf::PrimitiveType::Quads)
{
    switch (mType)
    {
    case particle::fire:
    {
        mTexture = &Resources::get()->getResource(Holder::particles, Texture::fire);
        particleLifetime = sf::seconds(1.25f);
        break;
    }
    }
}


void particleSystem::update(sf::Time timePerFrame)
{
    for (auto& particle : particles)
    {
        particle.leftLifetime -= timePerFrame;
    }
    while (!particles.empty() && particles.front().leftLifetime <= sf::Time::Zero) particles.pop_front();
}


void particleSystem::addParticle(sf::Vector2f position)
{
    particle newParticle;
    newParticle.position = position;
    switch (mType)
    {
    case particle::fire: newParticle.leftLifetime = particleLifetime; break;
    }

    particles.push_back(newParticle);
}


void particleSystem::draw(sf::RenderTarget& target, sf::RenderStates states) const
{
    updateVertices();
    states.texture = mTexture;
    target.draw(vertices, states);
}


void particleSystem::updateVertices() const
{
    sf::Vector2f textureSize(mTexture->getSize());
    sf::Vector2f halfTextureSize(textureSize / 2.f);

    vertices.clear();

    for (auto& particle : particles)
    {
        sf::Vector2f pos = particle.position;
        float alphaValue = va::max(0.f, 255.f * particle.leftLifetime.asSeconds() / particleLifetime.asSeconds());

        addVertex(sf::Vector2f(pos.x - halfTextureSize.x, pos.y - halfTextureSize.y), sf::Vector2f(0, 0), alphaValue);
        addVertex(sf::Vector2f(pos.x + halfTextureSize.x, pos.y - halfTextureSize.y), sf::Vector2f(textureSize.x, 0), alphaValue);
        addVertex(sf::Vector2f(pos.x + halfTextureSize.x, pos.y + halfTextureSize.y), sf::Vector2f(textureSize.x, textureSize.y), alphaValue);
        addVertex(sf::Vector2f(pos.x - halfTextureSize.x, pos.y + halfTextureSize.y), sf::Vector2f(0, textureSize.y), alphaValue);
    }
}


void particleSystem::addVertex(sf::Vector2f worldPos, sf::Vector2f texCoords, float alphaValue) const
{
    sf::Vertex newVertex;

    newVertex.color = sf::Color(255, 255, 255, alphaValue);
    newVertex.position = worldPos;
    newVertex.texCoords = texCoords;

    vertices.append(newVertex);
}

C-/C++-Quelltext

vertices.resize(4 * particles.size());