On Sun, 27 Jul 2025 18:48:18 GMT, Michael Strauß <mstra...@openjdk.org> wrote:
>> JavaFX unnecessarily restricts interpolation in the following ways: >> 1. `Interpolatable` implementations often clamp intermediate values to the >> interpolation factor range [0,1]. >> 2. `SplineInterpolator` doesn't accept Y coordinates outside of [0,1] for >> its control points. While this was probably done so that the computed >> interpolation factor doesn't exceed [0,1], the restriction goes far beyond >> that. For example, the following function is not representable, even though >> its values are all within the [0,1] range:<br> >> <img >> src="https://github.com/user-attachments/assets/368b6142-052d-4ead-8a59-cbddf4a19660"; >> width="400"/><br> >> The following function is also not representable, but would be very >> useful for [bouncy animations](https://easings.net/#easeOutBack):<br> >> <img >> src="https://github.com/user-attachments/assets/af02b044-ae4c-4250-b181-72178ad9f3f3"; >> width="400"/> >> >> Fortunately, there is no technical reason why JavaFX can't support the full >> range of animations that can be represented with a cubic Beziér >> interpolation function. >> >> This PR includes the following changes: >> 1. The specification of `Interpolatable` is changed to require >> implementations to accept interpolation factors outside of [0,1]. >> 2. All implementations of `Interpolatable` now correctly return intermediate >> values outside of [0,1]. >> 3. `SplineInterpolator` now accepts control points with any Y coordinate. >> >> Here's how the result looks like for the previously unrepresentable >> interpolation function `cubic-bezier(0.34, 2.2, 0.64, 1)`:<br> >> <img >> src="https://github.com/user-attachments/assets/72c10d0d-71b4-4bb5-b58c-ae377279b0fd"; >> width="500"/> > > Michael Strauß has updated the pull request with a new target base due to a > merge or a rebase. The incremental webrev excludes the unrelated changes > brought in by the merge/rebase. The pull request contains three additional > commits since the last revision: > > - Merge branch 'master' into feature/relaxed-interpolation > - javadoc > - Allow interpolation outside of range [0,1] Currently the workaround I use for this is to have a custom Interpolator implementation like: public class Cubic extends Interpolator { private final double x1; private final double y1; private final double x2; private final double y2; private static final double CUBIC_ERROR_BOUND = 0.001; public Cubic(double x1, double y1, double x2, double y2) { this.x1 = x1; this.y1 = y1; this.x2 = x2; this.y2 = y2; } double elevateCubic(double a, double b, double m) { return 3 * a * (1 - m) * (1 - m) * m + 3 * b * (1 - m) * m * m + m * m * m; } @Override public double curve(double t) { double start = 0.0; double end = 1.0; while (true) { final double midpoint = (start + end) / 2; final double estimate = elevateCubic(x1, x2, midpoint); if (Math.abs(t - estimate) < CUBIC_ERROR_BOUND) { return elevateCubic(y1, y2, midpoint); } if (estimate < t) { start = midpoint; } else { end = midpoint; } } } } Which allows me to define such curves: public static final MotionPreset EXPRESSIVE_FAST_SPATIAL = MotionPreset.of( new Cubic(0.42, 1.67, 0.21, 0.90), MEDIUM3 // Duration constant ); I believe I copied this from Flutter. (The new Material 3 Expressive makes use a lot of springs, see [Material 3 Docs](https://m3.material.io/styles/motion/overview/specs#1b299695-5822-4738-ae56-ef9389b412d2)) Unfortunately, I need to use such curves in CSS too, so I kinda need this commit to be merged ------------- PR Comment: https://git.openjdk.org/jfx/pull/1822#issuecomment-3213417480
