Function inverseLerp

inverseLerp(a, b, v): number
Compute the opposite of lerp. Given a and b and a value between a and b returns a value between 0 and 1. 0 if a, 1 if b. Note: no clamping is done.
Parameters
- a: number
  start value
- b: number
  end value
- v: number
  value between a and b
Returns number
(v - a) / (b - a)