Grey's framework uses FR right? Is delta timing better?
It actually uses BOTH. The fixed rate logic runs at 200FPS (you can change this) so for each frame drawn you get 3.something logic loops at 60Hz refresh rate and the last logic loop is drawn with a Delta value for ultimate smoothness. I don't use Tweening which is basically a third method. For slow motion all I need to do is modify the delta value by a multiplier (for the fixed rate loop it's normally 1 and it's a fraction of 1 on the last loop).Problem with delta timing is that if a big chunk of time is skipped due to some background task all the game objects will jump ahead and may move through solid objects. Fixed rate logic resolves this. Problem with fixed rate logic is that it may not work well on very slow PCs.