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Thread: Game Loop, calculate the Frames Per Second.

  1. #1
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    Default Game Loop, calculate the Frames Per Second.

    Ok, so first of all I would like to say that I'm still very 'Noob-ish' when it comes to programming in Java.

    I'm creating a simple game, however I thought it would be a nice challenge to display the frames per second in my game.
    But all the articles about it are really complex (for me) , and nobody seems to have a game loop the way I do.
    This is what my game loop looks like:

    My Main class extends the JPanel
     public class Main extends JPanel {

    Also in my main class the game loop, it uses the default repaint() method. In wich I draw all the images etc.
    public void run() {
      while (true) {
        long time = System.currentTimeMillis();
     
        repaint();
     
        time = (1000 / Globals.maxFPS) - (System.currentTimeMillis() - time);
     
        if (time > 0) {
          try {
            Thread.sleep(time);
          } catch (Exception e) }
        }
      }
    }


    My first thought was to calculate the FPS using the time variable, however no mather how slow the game goes time is always 16. So I realy don't understand how I should calculate the FPS in this game loop.

    If you need any more information I'll be happy to give it

    Thanks in Advance,
    Dirk


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    Crazy Cat Lady KevinWorkman's Avatar
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    Default Re: Game Loop, calculate the Frames Per Second.

    There are a couple ways to do this.

    Each frame, calculate the time (in seconds) it has been since the last frame. Divide 1 by that number, and that's your momentary fps.

    Do a similar calculation, only spread out over more time- every x number of frames, calculate how long it's been since the last x frames. Take x divided by that time, and that's your fps.

    Or do it the other way around- every second, calculate how many frames have passed. That's your fps. Or every 5 seconds, divided by 5.
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    Super Moderator Norm's Avatar
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    Default Re: Game Loop, calculate the Frames Per Second.

    it uses the default repaint() method. In wich I draw all the images etc.
    Do you have a repaint() method with your code in it? That is not normal and I don't know how it would work.
    The call to the repaint() method will return without much delay.
    (System.currentTimeMillis() - time) will be 0 most of the time.

    I'm not sure I understand your problem. Where is the FPS value shown?
    If you don't understand my answer, don't ignore it, ask a question.

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