Skip to content
MotionAtelier

Ease

Ease is the shape you draw yourself. It controls interpolation (how a value accelerates and decelerates between two keys) with knots and tangent handles.

Three cubic easing curvesCubic S-Curve starts and ends slowly; Cubic Accelerate starts slowly and ends fast; Cubic Decelerate starts fast and ends slowly.
  • Cubic S-Curve
  • Cubic Accelerate
  • Cubic Decelerate
Accelerate eases in, Decelerate eases out, S-Curve does both. The marker follows Cubic S-Curve. Plotted from MotionAtelier 0.4.2's own curve code, outside Houdini. An illustration of the curve, not a screen capture.

Where the Ease curve comes from

Section titled “Where the Ease curve comes from”

Choose SHAPE ▸ Ease, then start from any of these:

Source What you get
The default Sine S-Curve: an ease in and out with three knots. Restore Default Shape in the right-click menu brings it back.
Get Keys The motion between the selected keys in Houdini. See Get Keys.
An Ease recipe Double-click a recipe tile in the Recipes tab. See Recipes.
Convert to Ease The current Bounce, Elastic, Wave or Noise curve, copied into Ease for hand editing.
History A previously committed curve, with Restore. See History.

Each of these is one local undo step, so Ctrl+Z in the graph returns to the previous Ease curve. Then shape it in the curve editor or the velocity view.

Tangents and interpolation

Section titled “Tangents and interpolation”

Each knot has an incoming and an outgoing tangent:

  • The slope of a tangent is the speed at that knot. A flat tangent (slope 0) means the motion is at rest there: an ease.
  • The influence (handle length) is how long that speed is held into the segment. Long handles give a slow, lingering ease; short ones turn quickly.
  • Smooth knots share one slope, so the speed is continuous. Broken knots can change speed instantly.

When committed, every knot becomes a Houdini Bezier key with these slopes and handle lengths, scaled to the interval’s frames and values. See Commit Keys.

Factory easing recipes

Section titled “Factory easing recipes”

MotionAtelier ships 18 Ease recipes: six families, each as Accelerate (ease in), Decelerate (ease out) and S-Curve (both). Higher powers hold back longer and then move faster.

SineSine S-Curve with Sine Accelerate faint behind it: the gentlest family.
Sine
QuadraticQuadratic S-Curve with Quadratic Accelerate faint behind it.
Quadratic
CubicCubic S-Curve with Cubic Accelerate faint behind it.
Cubic
QuarticQuartic S-Curve with Quartic Accelerate faint behind it.
Quartic
QuinticQuintic S-Curve with Quintic Accelerate faint behind it.
Quintic
ExponentialExponential S-Curve with Exponential Accelerate faint behind it: the sharpest family.
Exponential

Each tile: S-Curve as the heavy line, Accelerate as the light line. Plotted from the recipes shipped with MotionAtelier, outside Houdini. These are illustrations, not screen captures.

The factory recipes are Bezier approximations of the classic easing functions, stored as a few knots. Like any recipe, they load into Ease and stay editable.

Section titled “Related”