Crate bevy_easings

Bevy Easings

Easings on Bevy components using interpolation.

Usage

System setup

Add the plugin to your app:

use bevy::prelude::*;
use bevy_easings::EasingsPlugin;

fn main() {
    App::new()
        .add_plugins(EasingsPlugin);
}

Easing a component to a new value

And then just ease your components to their new state!

use bevy::prelude::*;
use bevy_easings::*;

fn my_system(mut commands: Commands){
    commands
        .spawn((
            SpriteBundle {
                ..Default::default()
            },
            Sprite {
                custom_size: Some(Vec2::new(10., 10.)),
                ..Default::default()
            }
            .ease_to(
                Sprite {
                    custom_size: Some(Vec2::new(100., 100.)),
                    ..Default::default()
                },
                EaseFunction::QuadraticIn,
                EasingType::PingPong {
                    duration: std::time::Duration::from_secs(1),
                    pause: Some(std::time::Duration::from_millis(500)),
                },
            ),
        ));
}

If the component being eased is not already a component of the entity, the component should first be inserted for the target entity.

Easing using EaseMethod

The EaseMethod enum can be used to provide easing methods that are not avaliable in EaseFunction.

pub enum EaseMethod {
    /// Follow `EaseFunction`
    EaseFunction(EaseFunction),
    /// Linear interpolation, with no function
    Linear,
    /// Discrete interpolation, eased value will jump from start to end
    Discrete,
    /// Use a custom function to interpolate the value
    CustomFunction(fn(f32) -> f32),
}

This is shown below

use bevy::prelude::*;
use bevy_easings::*;

fn my_system(mut commands: Commands){
    commands
        .spawn((
            SpriteBundle {
                ..Default::default()
            },
            Sprite {
                custom_size: Some(Vec2::new(10., 10.)),
                ..Default::default()
            }
            .ease_to(
                Sprite {
                    custom_size: Some(Vec2::new(100., 100.)),
                    ..Default::default()
                },
                EaseMethod::Linear,
                EasingType::PingPong {
                    duration: std::time::Duration::from_secs(1),
                    pause: Some(std::time::Duration::from_millis(500)),
                },
            ),
        ));
}

Chaining easing

You can chain easings, if they are not set to repeat they will happen in sequence.

use bevy::prelude::*;
use bevy_easings::*;

fn my_system(mut commands: Commands){
    commands
        .spawn((
            SpriteBundle {
                ..Default::default()
            },
            Sprite {
                custom_size: Some(Vec2::new(10., 10.)),
                ..Default::default()
            }
            .ease_to(
                Sprite {
                    custom_size: Some(Vec2::new(300., 300.)),
                    ..Default::default()
                },
                EaseFunction::QuadraticIn,
                EasingType::Once {
                    duration: std::time::Duration::from_secs(1),
                },
            )
            .ease_to(
                Sprite {
                    custom_size: Some(Vec2::new(350., 350.)),
                    ..Default::default()
                },
                EaseFunction::QuadraticIn,
                EasingType::PingPong {
                    duration: std::time::Duration::from_millis(500),
                    pause: Some(std::time::Duration::from_millis(200)),
                },
            ),
        ));
}

Bundle Supported

• Sprite
• Transform
• Style

Custom component support

To be able to ease a component, it needs to implement the traits Default and Lerp. This trait is re-exported by beavy_easings.

use bevy::prelude::*;
use bevy_easings::*;

#[derive(Default, Component)]
struct CustomComponent(f32);
impl Lerp for CustomComponent {
    type Scalar = f32;

    fn lerp(&self, other: &Self, scalar: &Self::Scalar) -> Self {
        CustomComponent(interpolation::lerp(&self.0, &other.0, scalar))
    }
}

The basic formula for lerp (linear interpolation) is self + (other - self) * scalar.

Then, the system custom_ease_system::<CustomComponent> needs to be added to the application.

Examples

See examples

Ease Functions

Many ease functions are available:

• QuadraticIn
• QuadraticOut
• QuadraticInOut
• CubicIn
• CubicOut
• CubicInOut
• QuarticIn
• QuarticOut
• QuarticInOut
• QuinticIn
• QuinticOut
• QuinticInOut
• SineIn
• SineOut
• SineInOut
• CircularIn
• CircularOut
• CircularInOut
• ExponentialIn
• ExponentialOut
• ExponentialInOut
• ElasticIn
• ElasticOut
• ElasticInOut
• BackIn
• BackOut
• BackInOut
• BounceIn
• BounceOut
• BounceInOut

Bevy	bevy_easings
main	main
0.13	0.13
0.12	0.12
0.11	0.11
0.10	0.10
0.9	0.9
0.8	0.8
0.7	0.7
0.6	0.6
0.5	0.4

Structs

• EaseValue
  Wrapper around a type that can be eased.
• EasingChainComponent
  Component to control a chain of easing
• EasingComponent
  Component to control an easing
• EasingsPlugin
  Plugin to add systems related to easing

Enums

• EaseFunction
• EaseMethod
  Describe how eased value should be computed
• EasingDirection
  Direction of an easing. It can be backward with an EasingType::PingPong
• EasingState
  Control if an easing is played
• EasingType
  How should this easing loop repeat

Traits

• CustomComponentEase
  Trait to mark custom component that can be eased. It will be automatically implemented if the custom component implement Lerp
• Ease
  Trait marking components that can be eased
• Lerp
  Describes a type that can linearly interpolate between two points.

Functions

• custom_ease_system
  Ease system for custom component. Add this system to your application with your component as a type parameter.