The functions described in this chapter are declared in the header
The easing functions are an implementation of the functions presented in http://easings.net/, useful particularly for animations. Easing is a method of distorting time to control apparent motion in animation. It is most commonly used for slow-in, slow-out. By easing time, animated transitions are smoother and exhibit more plausible motion.
Easing functions take a value inside the range
[0.0, 1.0] and usually will
return a value inside that same range. However, in some of the easing
functions, the returned value extrapolate that range
http://easings.net/ to see those functions).
The following types of easing functions are supported:
Linear Quadratic Cubic Quartic Quintic Sine Circular Exponential Elastic Bounce Back
The core easing functions are implemented as C functions that take a time parameter and return a progress parameter, which can subsequently be used to interpolate any quantity.