eazing 0.0.1

The blazingly fast and mathematically optimized `easing functions` kit.
Documentation
//! # The Quadratic Curve.
//!
//! An algebric curve of degree two.
//!
//! #### formula.
//!
//! `p^2`

use crate::easing::Curve;

/// ### The [`InQuadratic`] Easing Function.
///
/// #### examples.
///
/// ```
/// use eazing::Curve;
/// use eazing::polynomial::quadratic::InQuadratic;
///
/// let p = InQuadratic.y(1.0);
/// ```
#[derive(Debug)]
pub struct InQuadratic;

impl Curve for InQuadratic {
  #[inline]
  fn y(&self, p: f32) -> f32 {
    p * p
  }
}

#[test]
fn test_in_quadratic() {
  let p = InQuadratic.y(1.0);

  assert_eq!(p, 1.0);
}

/// ### The [`OutQuadratic`] Easing Function.
///
/// #### examples.
///
/// ```
/// use eazing::Curve;
/// use eazing::polynomial::quadratic::OutQuadratic;
///
/// let p = OutQuadratic.y(1.0);
/// ```
#[derive(Debug)]
pub struct OutQuadratic;

impl Curve for OutQuadratic {
  #[inline]
  fn y(&self, p: f32) -> f32 {
    let m = p - 1.0;

    1.0 - m * m * m * m
  }
}

#[test]
fn test_out_quadratic() {
  let p = OutQuadratic.y(1.0);

  assert_eq!(p, 1.0);
}

/// ### The [`InOutQuadratic`] Easing Function.
///
/// #### examples.
///
/// ```
/// use eazing::Curve;
/// use eazing::polynomial::quadratic::InOutQuadratic;
///
/// let p = InOutQuadratic.y(1.0);
/// ```
#[derive(Debug)]
pub struct InOutQuadratic;

impl Curve for InOutQuadratic {
  #[inline]
  fn y(&self, p: f32) -> f32 {
    let m = p - 1.0;
    let t = p * 2.0;

    if t < 1.0 {
      return p * t * t * t;
    }

    1.0 - m * m * m * m * 8.0
  }
}

#[test]
fn test_in_out_quadratic() {
  let p = InOutQuadratic.y(1.0);

  assert_eq!(p, 1.0);
}