glsl-easings 
Robert Penner's easing functions in GLSL, available as a module for glslify.
I tried as best I could to make them speedy for GLSL, but I'm sure there are a lot of gaps to fill – pull requests welcome!
Usage
Each easing function has its own file which can be required from glslify:
# ease = require(glsl-easings/back-in-out)# ease = require(glsl-easings/back-in)# ease = require(glsl-easings/back-out)# ease = require(glsl-easings/bounce-in-out)# ease = require(glsl-easings/bounce-in)# ease = require(glsl-easings/bounce-out)# ease = require(glsl-easings/circular-in-out)# ease = require(glsl-easings/circular-in)# ease = require(glsl-easings/circular-out)# ease = require(glsl-easings/cubic-in-out)# ease = require(glsl-easings/cubic-in)# ease = require(glsl-easings/cubic-out)# ease = require(glsl-easings/elastic-in-out)# ease = require(glsl-easings/elastic-in)# ease = require(glsl-easings/elastic-out)# ease = require(glsl-easings/exponential-in-out)# ease = require(glsl-easings/exponential-in)# ease = require(glsl-easings/exponential-out)# ease = require(glsl-easings/linear)# ease = require(glsl-easings/quadratic-in-out)# ease = require(glsl-easings/quadratic-in)# ease = require(glsl-easings/quadratic-out)# ease = require(glsl-easings/quartic-in-out)# ease = require(glsl-easings/quartic-in)# ease = require(glsl-easings/quartic-out)# ease = require(glsl-easings/quintic-in-out)# ease = require(glsl-easings/quintic-in)# ease = require(glsl-easings/quintic-out)# ease = require(glsl-easings/sine-in-out)# ease = require(glsl-easings/sine-in)# ease = require(glsl-easings/sine-out)
And each function has the following signature:
float
Where t is a value between 0 and 1, returning a new float between 0 and 1.
License
MIT. See LICENSE.md for details.