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Hanging Ornament Sway Animation (Natural Pendulum Rotation Expression)

About This Expression

This expression creates a smooth, pendulum-like sway that mimics how a hanging object moves when affected by a gentle breeze. Instead of rigid or robotic motion, it produces a natural oscillation similar to ornaments, wind chimes, signboards, or hanging lights.

A key feature is the index-based phase offset, which ensures that when multiple layers use the same expression, they don’t all swing together. Each object starts its motion at a slightly different point in the sine wave, creating believable variation across a row of elements.

The result feels calm, physical, and organic—ideal for decorative motion.

How the Motion Works

  • Sine Wave Rotation
    A sine function creates smooth back-and-forth rotation, similar to a real pendulum.
  • Amplitude Control
    The amp value defines how wide the swing is.
  • Frequency Control
    The freq value controls how fast the ornament sways.
  • Index Offset
    Each layer gets a unique timing offset, preventing synchronized movement.
  • Optional Decay
    A decay value can be added if you want the motion to gradually settle and stop.

Expression

freq = 1.5;
amp = 15;
decay = 0; // Set to 0.1 if you want it to stop eventually
// Offset phase by index so ornaments sway differently
offset = index * 10;
Math.sin((time + offset) * freq) * amp;

How We Use This Expression

Step 1: Prepare the Ornament Layer

This expression works best on:

  • Shape layers
  • PNG ornaments
  • Icons or decorative elements
  • Text converted to shapes

Select the layer you want to animate.

Step 2: Set the Correct Anchor Point

  1. Select the Pan Behind Tool (Y)
  2. Move the Anchor Point to the top of the ornament (where it would hang)

This step is essential for realistic swinging motion.

Step 3: Apply the Expression to Rotation

  1. Press R to reveal Rotation
  2. Hold Alt (Windows) / Option (Mac) and click the Rotation stopwatch
  3. Paste the expression
  4. Click outside the editor to apply

The ornament will immediately begin swaying naturally.

Step 4: Duplicate for Natural Variation

  1. Duplicate the ornament layer multiple times
  2. Position them in a row or grid

Because the motion is offset using index, each ornament swings slightly differently—no extra setup required.

Step 5: Adjust the Motion Feel

Inside the expression, tweak:

  • amp → gentle sway or dramatic swing
  • freq → slow drift or breezy movement
  • decay → add damping if you want the motion to settle

Small adjustments can completely change the mood.

Step 6: Enhance the Look

You can improve realism by adding:

  • Subtle Motion Blur
  • Slight Scale or Opacity drift
  • Light shadow or glow
  • Soft wind sound effects

The expression handles motion; effects handle atmosphere.

Best Use Cases in After Effects

  • Hanging ornaments & decorations
  • Wind chimes and bells
  • Festive banners
  • UI elements with soft motion
  • Atmospheric background details

Why This Expression Works So Well

This setup feels natural because it respects real-world physics:

  • Smooth acceleration and deceleration
  • No abrupt stops
  • Slight timing variation between objects

Instead of manually animating dozens of layers, you get believable motion with one line of math.

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