sf::Window::GetFrameTime() returns 0

[Sutur]

Hello folks!

Everytime I call sf::Window::GetFrameTime() it returns 0 which can't be true.
It was working a few days ago and I did not update/change any of the SFML files.
Even if I put sf::Sleep( 0.5 ) inside my applications main loop, it still returns 0.
Any idea how this could be caused?

I'm using Linux 64bit ( Ubuntu ) together with g++ and SFML 2.0.

[Laurent]

Can you show your code?

[Sutur]

This prints 0 over and over again:

Code: [Select]

#include <SFML/Window.hpp>
#include <iostream>

int main()
{
sf::Window window( sf::VideoMode( 800, 600 ), "" );

while( window.IsOpened() )
{
sf::Event event;
while( window.GetEvent( event ) )
if( event.Type == sf::Event::KeyPressed || event.Type == sf::Event::Closed )
window.Close();

sf::Sleep( 0.5 );
window.Display();

std::cout << window.GetFrameTime() << std::endl;
}
}

[Laurent]

That's really weird. What if you directly use a sf::Clock instead?

[Hiura]

Isn't it the correct behaviour if you call Display right before GetFrameTime ?

[Revan1985]

i've always noticed that the GetFrameTime works only (on my pc), if i call it before the draw

Code: [Select]


sf::Sleep( 0.5);
std::cout << window.GetFrameTime() << std::endl;
window.Display();
     


this should work...

[Laurent]

GetFrameTime() can be called at any time, it returns the time from the last frame, not the current one. So the result doesn't depend on the moment when you call it.

[Sutur]

Code: [Select]


      std::cout << window.GetFrameTime() << std::endl;
      window.Display();

It keeps telling me 0.
So does the following code:

Code: [Select]


#include <SFML/Window.hpp>
#include <iostream>

int main()
{
   sf::Window window( sf::VideoMode( 800, 600 ), "" );
   sf::Clock frameTimeCounter;

   while( window.IsOpened() )
   {
      frameTimeCounter.Reset();

      sf::Event event;
      while( window.GetEvent( event ) )
         if( event.Type == sf::Event::KeyPressed || event.Type == sf::Event::Closed )
               window.Close();

      sf::Sleep( 0.5 );
      window.Display();
     
      std::cout << frameTimeCounter.GetElapsedTime() << std::endl;
   }
}

[Laurent]

Try to replace Sleep(0.5) with an active loop that takes some time.

[Sutur]

Try to replace Sleep(0.5) with an active loop that takes some time.

Does not change the behavior at all.

However, I managed to get it working by turning off Compiz.
Now the correct values are returned.
But I would really like it to work together with Compiz.
Please tell me if you can think of any solution.

Thanks in advance!

[Laurent]

Does not change the behavior at all.

So your program runs actively for a significant amount of time, and the clock still returns 0 second elapsed??

However, I managed to get it working by turning off Compiz.

Compiz usually conflicts with OpenGL stuff, I don't know how it can mess up time measurement.
SFML simply uses the gettimeofday function to measure time, there's nothing weird behind the sf::Clock class.

[Sutur]

So your program runs actively for a significant amount of time, and the clock still returns 0 second elapsed??

Yes, it did.
I switched to the latest SFML2 version( the one I was using before had been a few months old ) and it seems like it's now doing the job. I propably somehow messed up my previous SFML2 download.

Thanks for your help!