Enum EaseFunction 

#[non_exhaustive]
pub enum EaseFunction {
    Linear,
    QuadraticIn,
    QuadraticOut,
    QuadraticInOut,
    CubicIn,
    CubicOut,
    CubicInOut,
    QuarticIn,
    QuarticOut,
    QuarticInOut,
    QuinticIn,
    QuinticOut,
    QuinticInOut,
    SmoothStepIn,
    SmoothStepOut,
    SmoothStep,
    SmootherStepIn,
    SmootherStepOut,
    SmootherStep,
    SineIn,
    SineOut,
    SineInOut,
    CircularIn,
    CircularOut,
    CircularInOut,
    ExponentialIn,
    ExponentialOut,
    ExponentialInOut,
    ElasticIn,
    ElasticOut,
    ElasticInOut,
    BackIn,
    BackOut,
    BackInOut,
    BounceIn,
    BounceOut,
    BounceInOut,
    Steps(usize, JumpAt),
    Elastic(f32),
}

Curve functions over the unit interval, commonly used for easing transitions.

EaseFunction can be used on its own to interpolate between 0.0 and 1.0. It can also be combined with EasingCurve to interpolate between other intervals and types, including vectors and rotations.

Example

sample the smoothstep function at various points. This will return None if the parameter is outside the unit interval.

let f = EaseFunction::SmoothStep;

assert_eq!(f.sample(-1.0), None);
assert_eq!(f.sample(0.0), Some(0.0));
assert_eq!(f.sample(0.5), Some(0.5));
assert_eq!(f.sample(1.0), Some(1.0));
assert_eq!(f.sample(2.0), None);

sample_clamped will clamp the parameter to the unit interval, so it always returns a value.

assert_eq!(f.sample_clamped(-1.0), 0.0);
assert_eq!(f.sample_clamped(0.0), 0.0);
assert_eq!(f.sample_clamped(0.5), 0.5);
assert_eq!(f.sample_clamped(1.0), 1.0);
assert_eq!(f.sample_clamped(2.0), 1.0);

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

Linear

f(t) = t

QuadraticIn

f(t) = t²

This is the Hermite interpolator for

• f(0) = 0
• f(1) = 1
• f′(0) = 0

QuadraticOut

f(t) = -(t * (t - 2.0))

This is the Hermite interpolator for

• f(0) = 0
• f(1) = 1
• f′(1) = 0

QuadraticInOut

Behaves as EaseFunction::QuadraticIn for t < 0.5 and as EaseFunction::QuadraticOut for t >= 0.5

A quadratic has too low of a degree to be both an InOut and C², so consider using at least a cubic (such as EaseFunction::SmoothStep) if you want the acceleration to be continuous.

CubicIn

f(t) = t³

This is the Hermite interpolator for

• f(0) = 0
• f(1) = 1
• f′(0) = 0
• f″(0) = 0

CubicOut

f(t) = (t - 1.0)³ + 1.0

CubicInOut

Behaves as EaseFunction::CubicIn for t < 0.5 and as EaseFunction::CubicOut for t >= 0.5

Due to this piecewise definition, this is only C¹ despite being a cubic: the acceleration jumps from +12 to -12 at t = ½.

Consider using EaseFunction::SmoothStep instead, which is also cubic, or EaseFunction::SmootherStep if you picked this because you wanted the acceleration at the endpoints to also be zero.

QuarticIn

f(t) = t⁴

QuarticOut

f(t) = 1.0 - (1.0 - t)⁴

QuarticInOut

Behaves as EaseFunction::QuarticIn for t < 0.5 and as EaseFunction::QuarticOut for t >= 0.5

QuinticIn

f(t) = t⁵

QuinticOut

f(t) = (t - 1.0)⁵ + 1.0

QuinticInOut

Behaves as EaseFunction::QuinticIn for t < 0.5 and as EaseFunction::QuinticOut for t >= 0.5

Due to this piecewise definition, this is only C¹ despite being a quintic: the acceleration jumps from +40 to -40 at t = ½.

Consider using EaseFunction::SmootherStep instead, which is also quintic.

SmoothStepIn

Behaves as the first half of EaseFunction::SmoothStep.

This has f″(1) = 0, unlike EaseFunction::QuadraticIn which starts similarly.

SmoothStepOut

Behaves as the second half of EaseFunction::SmoothStep.

This has f″(0) = 0, unlike EaseFunction::QuadraticOut which ends similarly.

SmoothStep

f(t) = 3t² - 2t³

This is the Hermite interpolator for

• f(0) = 0
• f(1) = 1
• f′(0) = 0
• f′(1) = 0

See also smoothstep in GLSL.

SmootherStepIn

Behaves as the first half of EaseFunction::SmootherStep.

This has f″(1) = 0, unlike EaseFunction::CubicIn which starts similarly.

SmootherStepOut

Behaves as the second half of EaseFunction::SmootherStep.

This has f″(0) = 0, unlike EaseFunction::CubicOut which ends similarly.

SmootherStep

f(t) = 6t⁵ - 15t⁴ + 10t³

This is the Hermite interpolator for

• f(0) = 0
• f(1) = 1
• f′(0) = 0
• f′(1) = 0
• f″(0) = 0
• f″(1) = 0

SineIn

f(t) = 1.0 - cos(t * π / 2.0)

SineOut

f(t) = sin(t * π / 2.0)

SineInOut

Behaves as EaseFunction::SineIn for t < 0.5 and as EaseFunction::SineOut for t >= 0.5

CircularIn

f(t) = 1.0 - sqrt(1.0 - t²)

CircularOut

f(t) = sqrt((2.0 - t) * t)

CircularInOut

Behaves as EaseFunction::CircularIn for t < 0.5 and as EaseFunction::CircularOut for t >= 0.5

ExponentialIn

f(t) ≈ 2.0^(10.0 * (t - 1.0))

The precise definition adjusts it slightly so it hits both (0, 0) and (1, 1): f(t) = 2.0^(10.0 * t - A) - B, where A = log₂(2¹⁰-1) and B = 1/(2¹⁰-1).

ExponentialOut

f(t) ≈ 1.0 - 2.0^(-10.0 * t)

As with EaseFunction::ExponentialIn, the precise definition adjusts it slightly so it hits both (0, 0) and (1, 1).

ExponentialInOut

Behaves as EaseFunction::ExponentialIn for t < 0.5 and as EaseFunction::ExponentialOut for t >= 0.5

ElasticIn

f(t) = -2.0^(10.0 * t - 10.0) * sin((t * 10.0 - 10.75) * 2.0 * π / 3.0)

ElasticOut

f(t) = 2.0^(-10.0 * t) * sin((t * 10.0 - 0.75) * 2.0 * π / 3.0) + 1.0

ElasticInOut

Behaves as EaseFunction::ElasticIn for t < 0.5 and as EaseFunction::ElasticOut for t >= 0.5

BackIn

f(t) = 2.70158 * t³ - 1.70158 * t²

BackOut

f(t) = 1.0 + 2.70158 * (t - 1.0)³ + 1.70158 * (t - 1.0)²

BackInOut

Behaves as EaseFunction::BackIn for t < 0.5 and as EaseFunction::BackOut for t >= 0.5

BounceIn

bouncy at the start!

BounceOut

bouncy at the end!

BounceInOut

Behaves as EaseFunction::BounceIn for t < 0.5 and as EaseFunction::BounceOut for t >= 0.5

Steps(usize, JumpAt)

n steps connecting the start and the end. Jumping behavior is customizable via JumpAt. See JumpAt for all the options and visual examples.

Elastic(f32)

f(omega,t) = 1 - (1 - t)²(2sin(omega * t) / omega + cos(omega * t)), parametrized by omega

Trait Implementations

impl Clone for EaseFunction

fn clone(&self) -> EaseFunction

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for EaseFunction

impl Curve<f32> for EaseFunction

fn domain(&self) -> Interval

The interval over which this curve is parametrized.

fn sample_unchecked(&self, t: f32) -> f32

Sample a point on this curve at the parameter value t, extracting the associated value. This is the unchecked version of sampling, which should only be used if the sample time t is already known to lie within the curve’s domain.

fn sample(&self, t: f32) -> Option<T>

Sample a point on this curve at the parameter value t, returning None if the point is outside of the curve’s domain.

fn sample_clamped(&self, t: f32) -> T

Sample a point on this curve at the parameter value t, clamping t to lie inside the domain of the curve.

impl Debug for EaseFunction

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for EaseFunction

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl PartialEq for EaseFunction

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

Equality operator ==.

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

Inequality operator !=.

impl Serialize for EaseFunction

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for EaseFunction