What if Update Draw takes longer than 1/60 of a second? There are many reasons why this could happen: In summary, you don't need to do anything special to take advantage of our our fixed timestep logic.Just make sure you put all your game logic inside the Update method (not in Draw!The simplest situation is that the total time you spend in Update Draw is exactly 1/60 of a second.
Back when I was working on Allegro it caused the most common question from new programmers, and even though XNA does more than Allegro to handle time for you, it appears some people are still confused.
Hopefully this post will clarify how time works in the XNA Framework.
Microsoft XNA Game Studio 3.1 makes it easier than ever to create great video games for Windows-based PCs, Xbox 360 consoles (with an active premium XNA Creators Club subscription), and Zune digital media players.
I’ve gone through the first pass of updating the code in the book. Some of the chapters are still a little wonky as I’ve ran out of time.
But I wanted to get what I have done out into the public in case it was beneficial to anyone.