make sure EasingCurve has unit interval domain

crates/bevy_math/src/curve/easing.rs

@@ -50,6 +50,8 @@ where
 
  #[inline]
  fn sample_unchecked(&self, t: f32) -> T {
+ let domain = self.easing.domain();
+ let t = domain.start().lerp(domain.end(), t);
  self.start.lerp(self.end, self.easing.sample_unchecked(t))
  }
 }
@@ -62,8 +64,13 @@ where
  /// Create a new [`EasingCurve`] over the [unit interval] which transitions between a `start`
  /// and an `end` value based on the provided [`Easing`] curve.
  ///
+ /// If the input curve's domain is not the unit interval, then the [`EasingCurve`] will ensure
+ /// that this invariant is guaranteed by internally [reparametrizing] the curve to the unit
+ /// interval.
+ ///
  /// [unit interval]: `Interval::UNIT`
- pub fn new(start: T, end: T, easing: E) -> EasingCurve<T, E> {
+ /// [reparametrizing]: `Curve::reparametrize`
+ pub fn new(start: T, end: T, easing: E) -> Self {
  Self { start, end, easing }
  }
 }

crates/bevy_math/src/curve/mod.rs

@@ -1113,6 +1113,38 @@ mod tests {
  });
  }
 
+ #[test]
+ fn easing_curve_non_unit_domain() {
+ let start = Vec2::ZERO;
+ let end = Vec2::new(1.0, 2.0);
+
+ // even though the quadratic_ease_in input curve has the domain [0.0, 2.0], the easing
+ // curve correctly behaves as if its domain were [0.0, 1.0]
+ let curve = EasingCurve::new(
+ start,
+ end,
+ quadratic_ease_in().reparametrize(Interval::new(0.0, 2.0).unwrap(), |t| t / 2.0),
+ );
+
+ [
+ (-0.1, None),
+ (0.0, Some(start)),
+ (0.25, Some(Vec2::new(0.0625, 0.125))),
+ (0.5, Some(Vec2::new(0.25, 0.5))),
+ (1.0, Some(end)),
+ (1.1, None),
+ ]
+ .into_iter()
+ .for_each(|(t, x)| {
+ let sample = curve.sample(t);
+ match (sample, x) {
+ (None, None) => assert_eq!(sample, x),
+ (Some(s), Some(x)) => assert!(s.abs_diff_eq(x, f32::EPSILON)),
+ _ => unreachable!(),
+ };
+ });
+ }
+
  #[test]
  fn mapping() {
  let curve = function_curve(Interval::EVERYWHERE, |t| t * 3.0 + 1.0);