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Network / Occasional lags within UDP network

« on: October 03, 2010, 01:10:35 pm »

Hello!
We we are quite new to network programming, so we just wantet to try sfml with a small network program, that sends nothing but a single float.
For visualisation, we are drawing and rotating a sprite from the sfml graphics library, and send that to a 2nd computer, which draws a sprite with that value, too.

But here is the problem: Although most of the time it works flawlessly, every 10 to 15 seconds, the rotation stops and starts a few times, and than catches up fast again.  

So: are we having bad computers or are we doing something in this code terribly wrong, that causes lags?

Heres the sending part:

Code: [Select]

#include <iostream>
#include "SFML/Network.hpp"
#include "SFML/Graphics.hpp"

int main()
{
    sf::Clock Clock;

    sf::UdpSocket SendSocket;

    sf::IpAddress sender;
    sf::Packet paket;
    unsigned short port;
    float rotation;

    sf::RenderWindow App(sf::VideoMode(400, 300, 32), "SFML Network");

    sf::Sprite Sprite;
    Sprite.SetPosition(200.f, 150.f);
    Sprite.SetScale(60.f, 60.f);

    while (App.IsOpened())
    {
        sf::Event Event;
        while (App.GetEvent(Event))
        {
            if (Event.Type == sf::Event::Closed)
                App.Close();
        }

        rotation=Clock.GetElapsedTime()*100;
        paket << rotation;

        if(SendSocket.Send(paket, "127.0.0.1", 4567)!=sf::Socket::Done){
            std::cout << "Error" << std::endl;
        }
        std::cout << paket.GetDataSize() << std::endl;
        paket.Clear();



        Sprite.SetRotation(rotation);
        App.Clear();
        App.Draw(Sprite);
        App.Display();

        sf::Sleep(0.001f);
    }

    return EXIT_SUCCESS;
}


and the receiving part:

Code: [Select]


#include <iostream>
#include "SFML/Network.hpp"
#include "SFML/Graphics.hpp"

int main()
{
    sf::UdpSocket ReceiveSocket;
    if (ReceiveSocket.Bind(4567))
    {
        std::cout << "Error Binding" << std::endl;
    }

    sf::IpAddress sender;
    sf::Packet paket;
    unsigned short port;
    float rotation;

    sf::RenderWindow App(sf::VideoMode(400, 300, 32), "SFML Network");

    sf::Sprite Sprite;
    Sprite.SetPosition(200.f, 150.f);
    Sprite.SetScale(60.f, 60.f);

    while (App.IsOpened())
    {
        sf::Event Event;
        while (App.GetEvent(Event))
        {
            if (Event.Type == sf::Event::Closed)
                App.Close();
        }

        if(ReceiveSocket.Receive(paket, sender, port)!=sf::Socket::Done) {
            std::cout << "Error Recieving" << std::endl;
        }

        paket >> rotation;

        Sprite.SetRotation(rotation);
        App.Clear();
        App.Draw(Sprite);
        App.Display();
    }

    return EXIT_SUCCESS;
}



I hope, you find something in here, because, well...otherwise its our computers fault^^.

Best regards

Heinrich