Path: chuka.playstation.co.uk!scea!peter_alau@playstation.sony.com
From: Elliott Lee <tenchi@netmagic.net>
Newsgroups: scee.yaroze.beginners
Subject: Re: Questions about VSync.
Date: Tue, 12 May 1998 13:24:59 -0700
Organization: Cisco Systems
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Message-ID: <3558B01B.A01C8CF3@netmagic.net>
References: <354C8851.709D2E83@chowfam.demon.co.uk> <6ij6jd$jpr18@chuka.playstation.co.uk> <354D8AA7.17CA37C6@chowfam.demon.co.uk> <354E298F.2865CC25@netmagic.net> <354E4EA8.A92F3D10@chowfam.demon.co.uk> <3557BAFE.CD170013@ndirect.co.uk>
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Heya,

There's a better way than to just slap random digits on the end and
it's ACCURATE!  (I just implemented this for a real-time clock so I
know it works.)  Cut and paste this code snippet into the appropriate
places:

	// put in your constants definitions
	/* #define VIDEO_REFRESH 60 */
	#define	VIDEO_REFRESH	50

	// put in your variable declarations
	char	TimerBuf[8+1];
	long	RunningClock=0;

	// this is your main program loop
	while( ...whatever... )
          {

  	  // to calculate the minutes, seconds, and hundredths:
	  RunningClock++;
	  sprintf( TimerBuf,"%0.2d:%0.2d.%0.2d",
	    (RunningClock/VIDEO_REFRESH)/60,		// mins
	    (RunningClock/VIDEO_REFRESH)%60,		// secs
	    ((RunningClock*100)/VIDEO_REFRESH)%100	// 100ths
	    )
	  // now print out the TimerBuf somehow...

	  }  // end of the while...

Of course, you could increase the TimerBuf's storage space to 10+1
and change the 100ths to 1000ths or 10000ths, but that's your option.
This is pretty accurate as long as you don't miss a video frame.  And,
if you do, say, 25 FPS, then just change the VIDEO_REFRESH to 25.
etc. etc. etc...

^_^

Alex Herbert wrote:
> 
> James Chow wrote:
> 
> > I know it's not a good way to do timing, but are there any other
> > suggestions of how to get a finer resolution than 1/50th sec
> > or 1/60th sec?  But not too fine, eg. using the root counter, which
> > flies past like f*** and has probably "gone round" a few
> > times before you've checked again.
> >
> > Games like Ridge Racer have timers going down to 1/1000th sec
> > resolution. Now how to do they manage that?
> > Personally I find using vsync(-1) + rand()/RAND_MAX
> > a bit too tacky.
> >
> > Cheers.
> > --
> > jc
> 
> All games (with only a few exceptions) are clocked to 50 or 60Hz (PAL or
> NTSC). There is no point it having a higher resolution timer. Ridge Racer is
> only clocked at 25Hz ('cos it updates every other frame).  It's just an
> illusion.  Clock your game at 50Hz with vsync() and slap some random digits
> on the end.  No one will notice!
> 
> Herbs

-- 
- e!
  tenchi@netmagic.net
  http://www.netmagic.net/~tenchi/yaroze/