how does SFML internally maintain the frame rate limit when setFramerateLimit() function is used?-CodePudding

window.setFramerateLimit(60);
while(window.isOpen())
{
    //manage events
}

this above while loop runs 60 times in 1 second after we set the frame rate limit, I want to know how does SFML internally manage to run the while loop in a controlled manner(i.e maintaining frame rate) by just using the "window.isOpen()" function in while loop condition. Or is there anything else working under the hood.

I am unable to understand how does setFramerateLimit works in SFML.

CodePudding user response：

Setting setFramerateLimit on the window will add a delay after you call window.display(). If you remove the call to this function your loop would iterate without the limit control set by SFML.

CodePudding user response：

SFML limits the frame rate by sleeping the thread for a short interval each time you call window.display(). This can be seen in the source code:

void Window::display()
{
    // Display the backbuffer on screen
    if (setActive())
        m_context->display();

    // Limit the framerate if needed
    if (m_frameTimeLimit != Time::Zero)
    {
        sleep(m_frameTimeLimit - m_clock.getElapsedTime());
        m_clock.restart();
    }
}

Without calling this function once per loop, there is no frame rate limiting.