Accurate FPS - Printable Version

Accurate FPS - Printable Version

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Accurate FPS - Phate - Mar 22, 2003 09:52 PM

I'd like my animations and movement to be based on the FPS of the game, now the frames per second should be "1/(microsecondsSinceLastFrame*1000000)" (right?).

But one question, how do I get the microseconds so I can use them to say "microsecondsSinceLastFrame = microNow - microLastFrame"?

I tried just typing Microseconds(), but it appears to want an "UnsignedWide" and I don't know what that is exactly.

Thanks
phate

Accurate FPS - Patrick - Mar 22, 2003 10:20 PM

http://www.mactech.com/articles/develop/issue_26/minow.html

Code:

UnsignedWide    startTime;

UnsignedWide    endTime;

Microseconds(&startTime);

DoMyOperation();

Microseconds(&endTime);

Accurate FPS - OneSadCookie - Mar 23, 2003 02:06 AM

Cocoa

Code:

+[NSDate timeIntervalSinceReferenceDate]

POSIX

Code:

gettimeofday()

Carbon

Code:

GetCurrentEventTime()

Are generally the easiest ways to get accurate timings. All appear to be accurate to below the microsecond.

Accurate FPS - DoG - Mar 23, 2003 04:05 AM

I have exactly what you want...

Code:

#include <CoreServices/CoreServices.h>

double GetUpTime(void)

{

    AbsoluteTime atime = UpTime();

    Nanoseconds nsecs = AbsoluteToNanoseconds(atime);

    double     time = UnsignedWideToUInt64(nsecs);

    return time*1.0E-9;

};

This function returns the uptime of the machine in seconds, and on my machine (G4/400) two successive calls measure a delay of 1.3-1.4 microseconds.