Function inv_flerp

pub fn inv_flerp(start: f32, end: f32, point: f32) -> f32

calculate the percent for point between self and end

Usage

assert_eq!(inv_flerp(10.0, 20.0, 15.0), 0.5);
assert_eq!(inv_flerp(10.0, 20.0, 11.0), 0.1);