Glissade

Glissade is a Rust animations and transitions library. It's framework-agnostic with optional euclid and nalgebra support.

The lib contains two main types: Animation and InertialValue.

• Animation can be used in cases when we know start, end, and in between keyframes.
• InertialValue can be used to make an object smoothly follow a target value. For example, a particle following a cursor. Background color changing smoothly on theme change.

It also contains a set of easing functions to make animations more natural. See the Easing enum for more details.

Animation can be applied to any type that implements Mix trait. This trait is used to interpolate between two values. Mix trait is implemented for common types like f32, f64, bool, i8 - i64, u8 - u64, Option<T: Mix>, and tuples like (Mix, Mix), (Mix, Mix, Mix), etc.

Most of the methods receive SystemTime as a parameter to allow testing without mocks, and have a consistent behavior during a single animation frame. It's expected that time is received from SystemTime::now() once in the beginning of the frame, and used lately during the frame rendering.

Examples

Simple two-step animation

use glissade::{Easing, transition, Transition};
use std::time::{Duration, SystemTime};

// Create an animation template - a transition.
//
// This transition consists of two steps:
// 1. from 0.0 to 10.0 in 1 second linearly,
// 2. and then go to 5.0 with easing function.
let transition = transition(0.0)
    .linear_to(10.0, Duration::from_secs(1))
    .ease_to(5.0, Duration::from_secs(2), Easing::QuadraticInOut);

let now = SystemTime::now();
// Create an animation from the transition and start time.
let animation = transition.run(now);

assert_eq!(animation.get(now), 0.0);
assert_eq!(animation.get(now + Duration::from_millis(500)), 5.0);
assert_eq!(animation.get(now + Duration::from_secs(1)), 10.0);
assert_eq!(animation.get(now + Duration::from_secs(2)), 7.5);
assert_eq!(animation.get(now + Duration::from_secs(3)), 5.0);

Smoothly change color

use glissade::{InertialValue, Easing};
use std::time::{Duration, SystemTime};

type Color = (f32, f32, f32);

let start_time = SystemTime::now();

// Create initial black value
let value: InertialValue<Color> = InertialValue::new((0.0, 0.0, 0.0), start_time);

assert_eq!(value.get(start_time), (0.0, 0.0, 0.0));
assert_eq!(value.get(start_time + Duration::from_secs(1)), (0.0, 0.0, 0.0));

// Change color to white in one second
let value = value.go_to((1.0, 1.0, 1.0), start_time, Duration::from_secs(1));

assert_eq!(value.get(start_time), (0.0, 0.0, 0.0));
assert_eq!(value.get(start_time + Duration::from_millis(500)), (0.5, 0.5, 0.5));
assert_eq!(value.get(start_time + Duration::from_secs(1)), (1.0, 1.0, 1.0));
assert_eq!(value.get(start_time + Duration::from_secs(2)), (1.0, 1.0, 1.0));

// Change color to red in between the transition
let value = value.ease_to((1.0, 0.0, 0.0), start_time + Duration::from_millis(500), Duration::from_secs(2), Easing::Linear);

assert_eq!(value.get(start_time + Duration::from_millis(500)), (0.5, 0.5, 0.5));
assert_eq!(value.get(start_time + Duration::from_secs(1)), (1.0, 0.75, 0.75));
assert_eq!(value.get(start_time + Duration::from_secs(2)), (1.0, 0.25, 0.25));
assert_eq!(value.get(start_time + Duration::from_millis(2500)), (1.0, 0.0, 0.0));
assert_eq!(value.get(start_time + Duration::from_secs(4)), (1.0, 0.0, 0.0));

License

This project is licensed under the MIT License - see the LICENSE.md file for details.