Game Loop

The loop and render method of every Sprite is guaranteed to run 60 times a second, in that order. If the render method returns other Sprites, the returned Sprites will then call their own loop and render after render returns.

The render method has a parameter extrapolateFactor, a value between 0 and 1 representing how much time has passed before the next frame is scheduled. For example, each frame will take 16.667ms to run, but if there were 25ms since the last render, then extrapolateFactor will be 0.5 (there is 8.33ms spare). This can be used to extrapolate the position of a sprite ahead of time for a smoother gameplay experience.

The article Fix Your Timestep! covers this in more detail.