Compose NoBouncy with StiffnessMediumLow
The source comments that StiffnessMediumLow is the default stiffness of the springs in enter and exit transitions. Stiffness 400, damping 40 and mass 1 give a damping ratio of 1, so the spring is about critically damped. It settles to within 0.1% in 0.465 s. It never passes the end value.
Demo
Both boxes take 0.465 s. Playing at 0.5× speed.
Your system asks for reduced motion, so nothing plays. The chart shows the whole move.
Code
A spring has no fixed duration, so the CSS takes the settle time (465 ms) and a linear() string that follows the spring.
transition: translate 465ms linear(0, 0.0063, 0.0232, 0.0484, 0.0798, 0.1158, 0.1549, 0.1962, 0.2385, 0.2812, 0.3238, 0.3656, 0.4064, 0.4459, 0.4839, 0.5202, 0.5548, 0.5875, 0.6185, 0.6476, 0.6749, 0.7004, 0.7243, 0.7465, 0.7672, 0.7864, 0.8042, 0.8206, 0.8358, 0.8499, 0.8628, 0.8747, 0.8856, 0.8957, 0.9049, 0.9133, 0.9211, 0.9282, 0.9346, 0.9406, 0.946, 0.9509, 0.9554, 0.9595, 0.9633, 0.9667, 0.9698, 0.9726, 0.9752, 0.9775, 0.9796, 0.9816, 0.9833, 0.9849, 0.9863, 0.9876, 0.9888, 0.9899, 0.9909, 0.9917, 0.9925, 0.9933, 0.9939, 0.9945, 0.995, 0.9955, 0.996, 0.9964, 0.9967, 0.997, 0.9973, 0.9976, 0.9978, 0.998, 0.9982, 0.9984, 0.9986, 0.9987, 0.9988, 0.999, 1);el.animate({ translate: ['0 0', '240px 0'] }, { duration: 465, easing: 'linear(0, 0.0063, 0.0232, 0.0484, 0.0798, 0.1158, 0.1549, 0.1962, 0.2385, 0.2812, 0.3238, 0.3656, 0.4064, 0.4459, 0.4839, 0.5202, 0.5548, 0.5875, 0.6185, 0.6476, 0.6749, 0.7004, 0.7243, 0.7465, 0.7672, 0.7864, 0.8042, 0.8206, 0.8358, 0.8499, 0.8628, 0.8747, 0.8856, 0.8957, 0.9049, 0.9133, 0.9211, 0.9282, 0.9346, 0.9406, 0.946, 0.9509, 0.9554, 0.9595, 0.9633, 0.9667, 0.9698, 0.9726, 0.9752, 0.9775, 0.9796, 0.9816, 0.9833, 0.9849, 0.9863, 0.9876, 0.9888, 0.9899, 0.9909, 0.9917, 0.9925, 0.9933, 0.9939, 0.9945, 0.995, 0.9955, 0.996, 0.9964, 0.9967, 0.997, 0.9973, 0.9976, 0.9978, 0.998, 0.9982, 0.9984, 0.9986, 0.9987, 0.9988, 0.999, 1)', fill: 'both' });import { spring, springDuration, springLinear } from '../../core/motion/springs.js';
const k = 400, d = 40;
// per-frame code (window.seek, vawe.onFrame): t is seconds since the move starts
const x = 240 * spring(t, k, d);
// CSS and Web Animations: 465 ms, the linear() string above
el.animate(
{ translate: ['0 0', '240px 0'] },
{ duration: springDuration(k, d) * 1000, easing: springLinear(k, d), fill: 'both' },
);Numbers
- Stiffness
- 400k, with mass 1
- Damping
- 40d, with mass 1
- Damping ratio
- 1about critically damped
- Settle time
- 0.465 swithin 0.1% of the end
- Overshoot
- 0%stays inside the end
- Crosses the end
- 0times
- 50% of travel
- 0.084 s18% of the settle time
- 90% of travel
- 0.195 s42% of the settle time
- Natural frequency
- 20 rad/ssqrt(k)
- Ring period
- noneit does not oscillate
- Peak speed
- 3.42xtimes the average speed
- linear() points
- 81within 0.15% of travel
Computed with spring() and springDuration() from core/motion/springs.js. The settle time is the last moment the spring is more than 0.1% away from the end value; a library stops its own spring by its own rest thresholds, so its clock can run shorter.
Source of the numbers
| Jetpack Compose | androidx main at 9adbcd8 (compose animation-core 1.14.0-alpha01) |
| spring(dampingRatio = Spring.DampingRatioNoBouncy (1), stiffness = Spring.StiffnessMediumLow (400)) | Spring.DampingRatioNoBouncy, Spring.StiffnessMediumLow |
Conversion: Stiffness is used as it is with mass 1 (SpringSimulation takes the natural frequency as sqrt(stiffness)). damping = 2 x dampingRatio x sqrt(stiffness), the same c = 2 x naturalFreq x dampingRatio that SpringSimulation.getAcceleration uses.
Related springs
The four closest curves in this set, by the average gap between the two springs over their first seconds. A gap of 0.01 is invisible; 0.1 is a different feel.