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MotionAtelier

Elastic

Elastic moves a value past its target, swings back and forth around it with shrinking amplitude, and settles exactly on it.

Elastic with default parametersThe value rises past 1 to about 1.44, swings back below 1, overshoots again by less, and settles at 1.
Elastic, default parameters (Oscillations 3, Damping 0.25). Plotted from MotionAtelier 0.4.2's own curve code, outside Houdini. An illustration of the curve, not a screen capture.

Use it

Section titled “Use it”
  1. Set SHAPE ▸ Elastic.
  2. In the Motion Stack tab, set Oscillations and Damping.
  3. Preview, select the keys in Houdini, and press Commit Keys.

Parameters

Section titled “Parameters”
ControlRangeDefaultWhat it changes
Oscillations1 to 123Overshoots around the target before it settles. Each overshoot or undershoot is one oscillation. The duration does not change, so more oscillations make each swing quicker.
Damping0.02 to 0.70
slider to 0.60; type larger values		0.25Damping ratio: lower values swing longer, higher values settle sooner. Sets the size of the first overshoot (see the table below) and how fast the swings shrink.
Elastic with three Damping valuesLow damping swings almost as far as the full move in each direction; damping 0.5 overshoots only slightly.
  • Damping 0.08
  • Damping 0.25
  • Damping 0.50
Oscillations 3, with Damping 0.08, 0.25 and 0.50. Plotted from MotionAtelier 0.4.2's own curve code, outside Houdini. An illustration of the curve, not a screen capture.

How far the first swing overshoots the target, as a share of the whole move:

Damping 0.02 0.10 0.25 0.40 0.50 0.70
First overshoot 94 % 73 % 44 % 25 % 16 % 4.6 %

Each following swing is smaller by the same ratio: with Damping 0.25, the swings are 44 %, 20 % and 9 % of the move.

Elastic with one and with six oscillationsOne oscillation: a single overshoot and settle. Six: a quick series of shrinking swings around the target.
  • Oscillations 1
  • Oscillations 6
Damping 0.25, with Oscillations 1 and 6. Plotted from MotionAtelier 0.4.2's own curve code, outside Houdini. An illustration of the curve, not a screen capture.

Behaviour

Section titled “Behaviour”
  • Model. The swings follow the response of a damped spring released towards the target (an underdamped second-order system). Damping is its damping ratio.
  • Settles exactly. A real spring keeps swinging, ever smaller. Elastic stops after the chosen number of oscillations: after the last swing it returns to the target in one more half swing and arrives with zero speed, so the second key is reached cleanly.
  • Even timing. Swing peaks are evenly spaced: with n oscillations there is a peak every 1/(n + 1) of the interval.
  • Sparse. One key at the start, one at each peak (flat tangent), one at the end: n + 2 keys per interval. Each swing is one Bezier segment fitted to the exact spring shape, within 1.2 % of that swing’s size.
  • Damping limit. Above 0.70 the overshoot is under 5 % and a Bezier segment can no longer match the swing within that accuracy, so the range stops there. For a gentle settle without overshoot, use an Ease curve or a Spring effect with Damping 1.

Factory recipes

Section titled “Factory recipes”
Recipe Oscillations Damping
Single Overshoot 1 0.40
Gentle Settle 3 0.30
Spring Snap 6 0.15
Loose Wobble 12 0.06
Section titled “Related”
  • Bounce: rebound off the target instead of swinging through it.
  • Motion Stack: the Spring and Jiggle effects add similar motion on top of any shape.