Overview

Layer Parenting creates a parent-child relationship between layers where the parent layer influences the position, rotation, and scale of the child.

Null Objects are invisible layers that work well with parenting. They can be used with parenting to give another layer of control to your animations. 

How to Parent Layers

In a project with at least two layers, tap on the layer you want to be the child layer, then tap the Layer Parent button.

Step 1: Tap the Layer Parenting Button

Select the layer you want to be the parent from the menu that drops down. If you have selected a layer on the timeline, it'll be unavailable in the parenting menu because a layer cannot be parented to itself.

Step 2: Select the parent layer

The arrow indicates the parent of the child layer.

 If you want to unparent a child layer you've already parented, select "none" from the menu.

How to Use Parenting

• When you change the position of a parent, the child moves in tandem.
• When you rotate the parent, the child rotates around the axis of the parent layer.
• When you change the parent's scale, the child grows or shrinks proportionately.

These changes still take effect regardless of whether the child overlaps with the parent or is at a distance. The parenting relationship is one-way: moving, rotating, or scaling the child will not influence the parent. Moreover, layer order on the timeline does not affect parent relationships.

Parenting Hierarchies

Each layer can, at most, have one parent, but a parent can have unlimited children. A layer with children can also, in turn, have a parent, allowing layers to be chained together to perform sophisticated animations.

This project's layers are parented together in a chain to create a sophisticated crane animation.

Effects and Parenting

Effects on a parent layer that change the layer's position, rotation, and scale also affect children, as do selected warp effects. Effects with this behavior have the Layer Parenting tag in the Effect Browser, such as Bend, Oscillate, Auto-Shake, and Swing.

When the Move Along Path effect is added to a child layer, it will cause the child to move along the outline of the parent. This is useful with Vector Drawing to create curved paths for layers to follow.

The Parenting Helper Effect

The Parenting Helper effect adjusts the behavior of child layers when the parent's rotation or scale changes, allowing specific components of the transformation to be selectively ignored, reduced, or exaggerated. For example, when you want a layer to move as the parent rotates without changing its angle, like gondolas on a Ferris wheel.

This effect allows you to change the mode for Rotation and Scale individually. Each one has there possible options:

• The Normal setting is for default parenting behavior. 
• The Locked setting will prevent the child from rotating or changing size, although its position will change in tandem with the parent.
• The Weighted setting allows degrees of change based on the parent. For example, a weighted rotation of 200% will cause the child to rotate twice as much as the parent. Use the appropriate Rotation Weight or Scale Weight spinner for the adjustment.

Here is an example where the parent layer is rotated by 45 degrees:

Normal: The child rotates with the parent around the parent's pivot point.

Locked: The child's position changes with the parent's rotation, but the child itself does not rotate.

Weighted: The child's position changes with the parent's rotation, and the child rotates depending on the weighting value. At 200%, the child rotates twice the amount of the parent.

There is also an Auto Rotate option which will automatically apply rotation to the layer based on the horizontal or vertical movement of the parent layer.

This is useful for automatically animating wheels. If the wheel doesn't fill the layer, use Radius Adjust to compensate so that the amount of rotation is calculated correctly. For example, if the wheel only fills 70% of the layer, and the outside 30% is transparent, set Radius Adjust to -30.

How to add Null Objects

To add a Null Object on iPhone and Android, tap Add Layer, go to Object, and tap Null. 

On iPad, go to the Object tab, and tap Null.

You will see a wireframe indicating the position, scale, and angle of the Null Object. You can use it as a reference while editing, but it won't appear when the project is exported.

How to Use Null Objects

Null Objects can be used as parents of other layers. This can be useful in a few situations:

• When you want more control over a layer's animation using different keyframe timings for separate axes, you can parent that layer to a null object and then animate one axis on the null object. This may be useful when you want more control over the position along the Z-axis of a camera object. You can animate the X and Y position on the camera object and Z on the parent null layer. This also works with scale if you want independent keyframe animation for the X scale and Y scale.
• If you want to apply a motion effect uniformly to two or more layers and be able to animate them separately, you can parent them to a null object and apply the motion effect to the null object. 

Additional Notes

👉 By setting simultaneous position keyframes on a parent layer and child layer and applying easing to both, you can create a curved motion arc for the child layer.

👉 When you split a parent layer into two halves, the children remain parented to the left half.

👉 The playhead position when you set a layer's parent can matter. A child layer's position, rotation, and scale are calculated based on the parent. To avoid a child layer jumping when you set a parent, Alight Motion will automatically adjust the child's position, rotation, and scale to compensate when you place the parent. This means the positional relationship between the child and parent layers is locked in when you apply parenting. This means that if the parent or child has an animation applied, it's essential to scroll the playhead to a position where the layers have the relationship you want before setting up parenting.