Struct Ease 

pub struct Ease {
    pub x1: f32,
    pub y1: f32,
    pub x2: f32,
    pub y2: f32,
}

The one easing curve every surface moves on, as CSS’s cubic-bezier(x1, y1, x2, y2) with the endpoints pinned at (0, 0) and (1, 1).

Both y control points must stay inside 0.0..=1.0. That is what keeps the curve monotone — an envelope that overshoots and comes back would make a panel’s alpha rise past its target and fall again. Both x control points must stay inside 0.0..=1.0 too, which is what makes x(t) invertible.

Fields

x1: f32

First control point, time axis.

y1: f32

First control point, progress axis.

x2: f32

Second control point, time axis.

y2: f32

Second control point, progress axis.

Implementations

impl Ease

pub fn at(self, t: f32) -> f32

Progress at normalised time t: 0.0 at t <= 0, 1.0 at t >= 1, and the curve’s height in between.

Solves x(s) = t by bisection on the curve parameter s — a fixed 40 halvings in f64, which puts s well inside an f32 step of the root and allocates nothing.

Monotone in t to the last bit, by construction. The height is read at the bisection’s lower bound, which never decreases as t grows (every comparison t passes, a larger t passes too), and it is computed in f64 and rounded once — an f32 evaluation of the height wobbles by an ulp near the top of a flat ease-out, which is a panel’s alpha stepping back down on its last frames.

pub fn css(self) -> String

The CSS spelling, cubic-bezier(x1, y1, x2, y2).

Trait Implementations

impl Clone for Ease

fn clone(&self) -> Ease

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Ease

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl PartialEq for Ease

fn eq(&self, other: &Ease) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for Ease

impl StructuralPartialEq for Ease