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Graphics / Why is window.draw(entity) working?

« on: November 24, 2016, 06:33:29 pm »

I'm following the tutorials on SFML, and everything's clear except why this example is actually working.
When creating our own entity, we're suggested to derive a class from Drawable (and possibly from Transformable), and override the pure virtual function sf::Drawable::draw.
The reason for that is so that we can call the draw function through window. Since window is a RenderWindow, and it inherits its draw function form its base class RenderTarget, this will call sf::RenderTarget::draw.

As far as I know sf::RenderTarget::draw does nothing else but call sf::Drawable::draw, so:

void RenderTarget::draw(const Drawable& drawable, const RenderStates& states)
{
    drawable.draw(*this, states);
}

Now here's the problem: sf::Drawable::draw (our overriden version of it has to make a call to sf::RenderTarget::draw as well! According to the tutorial:

    virtual void draw(sf::RenderTarget& target, sf::RenderStates states) const
    {
        // apply the entity's transform -- combine it with the one that was passed by the caller
        states.transform *= getTransform(); // getTransform() is defined by sf::Transformable

        // apply the texture
        states.texture = &m_texture;

        // you may also override states.shader or states.blendMode if you want

        // draw the vertex array
        target.draw(m_vertices, states);
    }

How does it not go into an infinite loop? I've been trying to figure out this for a while and I just can't understand.
Sorry if this has been asked before, I haven't found an answer for it.