Game loop design - your considerations

[SHC]

I had been using this run method as game loop.

1   2   3   4   5   6   7   8   9   10   11   12   13   14   15   16   17   18   19   20   21   22   23   24   25   26   27   28   29   30   31   32   33   34   35   36   37   38   39   40   41   42   43   44   45   46   47   48   49   50   51   52

public void run(){     // Initialize the resources    Map.initMap();     initResources();     // Game loop initialization    int SKIP_STEPS = 1000/Global.STEPS_FOR_SECOND;     // The time    long gameTime = getCurrentTime();     int loops;     // FPS counter    int frames = 0;     long lastFPSCount = getCurrentTime();     // UPD counter    int updates = 0;     long lastUPDCount = getCurrentTime();     // The current time    long now;     // Benchmarking    long updStartTime = 0;     long updEndTime = 0;     long updTime = 0;     while (running){         now = getCurrentTime();         loops = 0;         updStartTime = getCurrentTime();         while(now>gameTime && loops<Global.MAX_FRAMESKIP){             updateGame(SKIP_STEPS);             // calculate update count            updates++;             if (now - lastUPDCount > 1000){                 lastUPDCount = getCurrentTime();                 Global.ACTUAL_STEPS_FOR_SECOND = updates;                 Global.UPDATE_RATE = (int)((float)((float)Global.ACTUAL_STEPS_FOR_SECOND/(float)Global.STEPS_FOR_SECOND)*100);                 updates = 0;             }             gameTime += SKIP_STEPS;             loops++;         }         updEndTime = getCurrentTime();         updTime = updEndTime - updStartTime;         System.out.println(updTime);         interpolation = (now + SKIP_STEPS - gameTime)/SKIP_STEPS;         displayGame();         // FPS counter        frames++;         if (now - lastFPSCount > 1000) {             lastFPSCount = now;             Global.FRAMES_PER_SECOND = frames;             frames = 0;         }     } }

But the output of the bench marking is

1   2   3   4   5   6   7   8   9

59 8 2 2 1 1 2 1 0

I couldn't understand why 0's appear as elapsed time for updates. Also the STEPS_PER_SECOND is 50. Thanks.

[ReBirth]

If the updateGame(SKIP_STEPS) doesnt do anything, it's normal right?

[SHC]

That method isn't empty, it moves the objects and checks collisions. The objects are nearly 100

Games published by our own members! Check 'em out!

[ReBirth]

After narrowing down your code

1   2   3   4   5   6   7   8   9   10   11   12   13

while (running){         now = getCurrentTime();         loops = 0;         updStartTime = getCurrentTime();         while(now>gameTime && loops<Global.MAX_FRAMESKIP){             updateGame(SKIP_STEPS);             gameTime += SKIP_STEPS;             loops++;         }         updEndTime = getCurrentTime();         updTime = updEndTime - updStartTime;         System.out.println(updTime);     }

I suspect the 2nd while loop is not executed on later. The 'loops<Global.MAX_FRAMESKIP' looks pretty "stable". Try to debug the 'now' and 'gameTime'.

[SHC]

I tried printing them out every loop. Sometimes they're becoming equal. This other question I've asked helped me.

http://gamedev.stackexchange.com/questions/42010/passing-elapsed-time-to-the-update-function-from-the-game-loop/42018#42018

Thanks for the help

[ReBirth]

First, you should avoid calling getCurrentTime() multiple times per loop. You will potentially be getting different values at different times.

I just know about this, but yes it seems true