o you [i]really[/i] need to use delta times? I know that people call this frame independent movement, and it's certainly how I learned to make games at first, but a fixed time step is way… way.. way… better in almost every case. Especially if your game has physics… even something as simple as “friction” where you take speed*friction (say friction=0.9) every frame gets wonky if there's a dt.
What I had to realize in order to ditch delta times was that there's no reason to couple your render pass with your logic …