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Help => General => Topic started by: kamac on March 30, 2015, 07:47:49 pm

Title: Polling network messages & VSYNC
Post by: kamac on March 30, 2015, 07:47:49 pm

Hey there.

I am using a 3rd party networking library, and I need to poll my packets as often as possible - framerate independent. But I also would like to have VSYNC enabled.

How do I go about that? When I turn VSYNC on, window.display() will block for a certain amount of time, and there's no way around it. I can't run my packet polling on a separate thread.

Should I just manually limit the framerate, and poll my packets independently? But that wouldn't be like turning VSYNC on - it'd be just limiting the framerate, right?

Cheers.

Title: Re: Polling network messages & VSYNC
Post by: Nexus on March 30, 2015, 08:04:32 pm

When there is enough time left in the current frame, you can poll more than once. Thus, you have different rates for polling and screen update.

See also here (http://en.sfml-dev.org/forums/index.php?topic=17816.0), some of the resources mentioned by Jesper Juhl address this issue, too.

Title: Re: Polling network messages & VSYNC
Post by: kamac on March 30, 2015, 08:10:13 pm

I don't quite follow. I can't do anything during the time window.display() is called - and it will block for some milliseconds, for Vsync's sake. How can I poll my stuff during that time on the same thread? (By poll I mean call an object's member function, not poll keyboard events)

Didn't find the answer in the link you've linked.

Title: Re: Polling network messages & VSYNC
Post by: Jesper Juhl on March 30, 2015, 09:31:27 pm

Of course you can't do anything while display() blocks. But if there's extra time left in the current frame you can poll() your network stuff a few times before calling display().
It's all about keeping track of the time spent per frame and managing how it is used.

Title: Re: Polling network messages & VSYNC
Post by: kamac on March 30, 2015, 11:06:38 pm

But if I turn VSync on, won't swapping buffers block by itself? Maybe I'm getting the wrong idea, but each time I turned it on, my framerate dropped to 60 FPS.

Title: Re: Polling network messages & VSYNC
Post by: Nexus on March 30, 2015, 11:11:01 pm

You were able to do other things between two display() calls, like game logic, so why shouldn't you be able to poll the network?

Title: Re: Polling network messages & VSYNC
Post by: kamac on March 30, 2015, 11:29:26 pm

Uh,

Quote

But if I turn VSync on, won't swapping buffers block by itself? Maybe I'm getting the wrong idea, but each time I turned it on, my framerate dropped to 60 FPS.

Buffer swap occurs on .display().

@EDIT
Nevermind, figured it out.