FTween is a simple tweening utility designed to fill a need not met by the Penner family of time-based tweening solutions. The problem case is one where a target is constantly moving and/or changing at unexpected times. The Penner equations rely on the assumption that a tween will last for a known length of time, but it is often the case that I simply want a smooth transition from one state to another. Tweening content for smooth scrolling and animating a tree menu are two common examples where time-based tweening can have stuttering or less than desirable result. When animating a sprite in such as way that it follows a moving target, Penner tweens don’t work at all.

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