Brian Peek [MVP C#]

Thanks for the link.  I've been bitten on the PC side by these inaccuracies in the past, but this time it wasn't the PC I found inaccurate in all of my testing, but the Xbox.  Unfortunately since the CompactFramework is new to this platform and the fact that it is the CF, my options for timing are limited.

Also note that the issue I was having wasn't that I wouldn't get updates to the tick count fast enough, but the fact that the tick count was just plain wrong.

My sample app that proved the point showed that the Stopwatch (which uses QPC internally on the 360) actually redefined the length of a millisecond.  :)  The sample app would start a Stopwatch and grab the time value for DateTime.UtcNow.Ticks and compare the two over time.  You can watch the difference between the two values increase at a constant rate such that after 1 minute, the value returned from DateTime.UtcNow.Ticks was indeed real time, and the value returned by the Stopwatch was 150ms in the past.  After 2 minutes, it was 300ms off.  After 3, 450ms.

Quite bizarre, but according to the Stopwatch on the 360's CF, a millisecond isn't quite a milisecond, but DateTime.UtcNow.Ticks was perfectly accurate for my needs.

Dan,

I assume you're using XNA since you're posting here.  ;)

I'm not 100% sure I understand the question at hand, but I would be maintaining a list of projectiles and enumerating the list once per call to the XNA Update method.  Here I'd take the elapsed ticks passed into the Update method to determine how far each projectile would have moved in that time frame.

So, you'd like have a Projectile class which contains its own update method, also taking in a TimeSpan of elapsed time since the last frame.  So, something like this in your main game screen (pseudo-code):

void Update(GameTime time)

{

 foreach(Projectile p in projectiles)

   p.Update(time);

}

void Draw(GameTime time)

{

 foreach(Projectile p in projectiles)

   p.Draw(time);

}

Then in your Projectile class (pseudo-code again):

void Update(GameTime time)

{

 this.X = VelocityX * time.ElapsedTime.TotalMilliseconds;

}

Hope that makes some amount of sense.  If not, feel free to post back here, post to my forum at www.brianpeek.com or fire off an email to me at "my first name@my first and last name.com" .  :)

Dan,

Not sure I understand...when/why would you be getting multiple updates in a single frame?

Update: This issue has been fixed in XNA Game Studio 2.0. Woo hoo! While working on my game for Maker

Update: This issue has been fixed in XNA Game Studio 2.0. Woo hoo! While working on my game for Maker