TweenDreams is a large collection of scripts that will allow you to easily add tweens and easing functions to your games.
Try The Demo Application for Windows here.
The core of this extension is a collection of easing equations. These equations perform non-linear interpolations that produce a variety of curves. The remaining scripts are wrapper functions to cover many of the common uses for easing.
Using an easing function for animation is often called tweening. The Built-In Variable tween functions will handle many animations such as movement, scaling, and rotation. The Custom Variable tween functions can be used to handle more complex tasks such as changing variables used in advanced draw functions.
There are many other uses for easing functions that do not need to update every frame. The twerp() function can be used like lerp() to interpolate between two values. This can be used in RPG stat systems, scaling damage calculations, scaling motion trails, and in many other situations.