.Net DateTime.Now not frequent enough?

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Gareth - 20 Sep 2007 09:48 GMT

I am trying to use DateTime.Now to apply a frame limit to my 3d
application. Below is the code involved. In this example I have hard
coded it for 60 frames per second (1000 milliseconds / 60 fps).

public void Execute()
{
    while(!_close)
    {
        DateTime n=DateTime.Now;
        TimeSpan t=n.Subtract(_lastRender);

        if(t.TotalMilliseconds>=1000.0d/60.0d)
        {
            _lastRender=n;
            _render();
        }
    }
}

The problem is I always get 33 frames per second. If I remove the
frame limiter I get 2000+ frames per second. If I log the value of
t.TotalMilliseconds to a text file every iteration I get the
following:

Notice that TotalMilliseconds doesn't change at all for several
iterations, then suddenly doubles...

20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 15.6279
20/09/2007 09:50:11: 31.2558
20/09/2007 09:50:11: 0
20/09/2007 09:50:11: 0
20/09/2007 09:50:11: 0
20/09/2007 09:50:11: 0

Reply to this Message

Henning Krause [MVP - Exchange] - 20 Sep 2007 11:00 GMT

Hello,
you should probably use the StopWatch instead (if you are using .NET 2.0),
which uses a high-resolution timer.

With .NET 1.1, you can still interop into Win32 QueryPerformanceCounter and
QueryPerformanceFrequency functions.

Kind regards,
Henning Krause

>I am trying to use DateTime.Now to apply a frame limit to my 3d
> application. Below is the code involved. In this example I have hard
[quoted text clipped - 77 lines]
> 20/09/2007 09:50:11: 0
> 20/09/2007 09:50:11: 0

Reply to this Message

Gareth - 20 Sep 2007 14:07 GMT

> Hello,
> you should probably use the StopWatch instead (if you are using .NET 2.0),
[quoted text clipped - 5 lines]
> Kind regards,
> Henning Krause

Thanks, using QueryPerformanceCounter/Frequency has done the job!

A nice smooth 60fps :D

G

Reply to this Message

.Net DateTime.Now not frequent enough?

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