Rendering on closed window

[Nexus]

The typical SFML example looks like this:

sf::RenderWindow window(...);
sf::Sprite sprite(...);

while (window.isOpen())
{
        sf::Event event;
        while (window.pollEvent(event))
        {
                if (event.type == sf::Event::Closed)
                        window.close();
        }

        window.clear();
        window.draw(sprite);
        window.display();
}

After the event has fired and the close() function has been called, the three rendering-related functions are still invoked. Earlier this led to OpenGL error messages, now I think the behavior is protected by the sf::RenderTarget::activate() calls. Is this a potential problem, or only an esthetical one?

In the Thor examples, I have always used for (;;) and return 0; to leave the loop directly.

[Laurent]

It's totally safe, but maybe I should adopt a "cleaner" convention.

Solution #1:

while (window.isOpen())
{
        window.clear();
        window.draw(sprite);
        window.display();

        sf::Event event;
        while (window.pollEvent(event))
        {
                if (event.type == sf::Event::Closed)
                        window.close();
        }
}

Solution #2:

bool running = true;
while (running)
{
        sf::Event event;
        while (window.pollEvent(event))
        {
                if (event.type == sf::Event::Closed)
                        running = false;
        }

        window.clear();
        window.draw(sprite);
        window.display();
}

I don't like yours infinite loops don't look clean and trigger warnings with some compilers. And although I'm not a big fan of the SESE (single entry, single exit) rule, for the main() function it feels better to have a single return statement at the end, rather than one in the middle of the loop.

[Celtic Minstrel]

Um, #2 still renders on the closed window.

[Laurent]

#2 doesn't close the window, it leaves that to the destructor when main() returns. sf::Event::Closed is a close request, not a notification; if you don't explicitely close the window it remains open.

[Celtic Minstrel]

Oh right. Duh. <_<