Struct Tween 

pub struct Tween { /* private fields */ }

Linear interpolation between two values over a duration, with optional easing.

A Tween advances from from to to over duration_ticks render ticks. Call Tween::value each frame with the current tick to get the interpolated value. The tween is inactive until Tween::reset is called with a start tick.

Example

use slt::Tween;
use slt::anim::ease_out_quad;

let mut tween = Tween::new(0.0, 100.0, 20).easing(ease_out_quad);
tween.reset(0);

let v = tween.value(10); // roughly halfway, eased
assert!(v > 50.0);       // ease-out is faster at the start

Implementations

impl Tween

pub fn new(from: f64, to: f64, duration_ticks: u64) -> Self

Create a new tween from from to to over duration_ticks ticks.

Uses linear easing by default. Call Tween::easing to change it. The tween starts paused; call Tween::reset with the current tick before reading values.

pub fn easing(self, f: fn(f64) -> f64) -> Self

Set the easing function used to interpolate the value.

Any function with signature fn(f64) -> f64 that maps [0, 1] to [0, 1] works. The nine built-in options are in this module.

pub fn on_complete(self, f: impl FnMut() + 'static) -> Self

Register a callback that runs once when the tween completes.

pub fn value(&mut self, tick: u64) -> f64

Return the interpolated value at the given tick.

Returns to immediately if the tween has finished or duration_ticks is zero. Marks the tween as done once tick >= start_tick + duration_ticks.

pub fn is_done(&self) -> bool

Returns true if the tween has reached its end value.

pub fn reset(&mut self, tick: u64)

Restart the tween, treating tick as the new start time.