Java-Gaming.org Hi !
Featured games (90)
games approved by the League of Dukes
Games in Showcase (686)
Games in Android Showcase (198)
games submitted by our members
Games in WIP (758)
games currently in development
News: Read the Java Gaming Resources, or peek at the official Java tutorials
 
    Home     Help   Search   Login   Register   
Pages: [1]
  ignore  |  Print  
  Game loop and frames per second  (Read 1190 times)
0 Members and 1 Guest are viewing this topic.
Offline RonnieDeRakker

Innocent Bystander




Java games rock!


« Posted 2004-07-10 11:40:25 »

Hi y'all I see some strange things happening when I use the following code to create a game loop:

private static final int MAX_CPS = 50;
private static final int MS_PER_FRAME = 1000 / MAX_CPS;

public void run()
{
 while (running)
 {
   long cycleStartTime = System.currentTimeMillis();

   repaint();

   if (System.currentTimeMillis() - lastCPSTime > 1000)
   {
     lastCPSTime = System.currentTimeMillis();
     cps = cyclesThisSecond;
     cyclesThisSecond = 0;
   }
   else
     cyclesThisSecond++;

   long timeSinceStart = (System.currentTimeMillis() - cycleStartTime);
   if (timeSinceStart < MS_PER_FRAME)
   {
     try
     {
       Thread.sleep(MS_PER_FRAME - timeSinceStart);
     }
     catch (InterruptedException e) {}
   }
 }
}

As you can see, it's just a regular gameloop. The variable cps is drawn to screen every second.
However when I set MAX_CPS=50, cps has the value of 32. When MAX_CPS=40, then cps is still 32! When MAX_CPS=30 then cps is 20. When MAX_CPS=65 then cps is 65! When MAX_CPS=100, then cps is still 65!

I can understand there's some overhead in using the Thread.sleep statement, but this behaviour I cannot explanin.

Can somebody shine a light on this?

Thanx!
Ronnie

Offline Abuse

JGO Ninja


Medals: 50


falling into the abyss of reality


« Reply #1 - Posted 2004-07-10 12:25:43 »

currentTimeMillis has a resolution of ~50ms on Win9x, and ~10ms in WinNT>.

Thread.sleep() doesn't have an outstanding accuracy either.

Without having a closer look at your loop, I can't say for sure if that is the cause though....
I never bother with sleep myself, better to hope for vsync, or tight loop on the timer. =)

:edit:

oh heyup, this is in the J2ME forum isn't it =)

Tight loop on the timer then.
(shame MIDP2.0 gave us a load of substandard 'game API' classes, instead of useful stuff like a method to expose the vblank signal)
Pages: [1]
  ignore  |  Print  
 
 
You cannot reply to this message, because it is very, very old.

 
roseslayer (538 views)
2016-08-06 11:43:29

roseslayer (494 views)
2016-08-06 09:43:11

xTheGamerCodes (568 views)
2016-08-04 15:40:59

xTheGamerCodes (563 views)
2016-08-04 15:40:24

orrenravid (908 views)
2016-07-16 03:57:23

theagentd (985 views)
2016-07-11 14:28:54

Hydroque (1083 views)
2016-07-06 05:56:57

Hydroque (1054 views)
2016-07-03 08:52:54

GrandCastle (870 views)
2016-07-01 09:13:47

GrandCastle (645 views)
2016-07-01 09:09:45
Rendering resources
by Roquen
2016-08-08 05:55:21

Rendering resources
by Roquen
2016-08-08 05:52:42

Rendering resources
by Roquen
2016-08-08 05:50:38

Rendering resources
by Roquen
2016-08-08 05:49:53

Rendering resources
by Roquen
2016-08-08 05:32:39

Making a Dynamic Plugin System
by Hydroque
2016-06-25 00:13:25

Java Data structures
by BinaryMonkL
2016-06-13 21:22:09

Java Data structures
by BinaryMonkL
2016-06-13 21:20:42
java-gaming.org is not responsible for the content posted by its members, including references to external websites, and other references that may or may not have a relation with our primarily gaming and game production oriented community. inquiries and complaints can be sent via email to the info‑account of the company managing the website of java‑gaming.org
Powered by MySQL Powered by PHP Powered by SMF 1.1.18 | SMF © 2013, Simple Machines | Managed by Enhanced Four Valid XHTML 1.0! Valid CSS!