Parenting & Nulls

Parenting makes one object's transform follow another's. The child keeps its own transform; that transform is now expressed inside the parent's frame, so moving the parent carries the child, and the child's own animation still plays on top.

The parent pick-whip#

The pick-whip is a menu at the right of the Layer column, on layer and null rows only. Its label reports the current state: nothing when the row is unparented, the parent's name when it has one, and <n> parents when it has several. It tints as soon as a parent is set.

Several parents at once#

A layer may have more than one parent. When it does, the transform it inherits is the equal-weight blend of all of them — the primary parent first, then the extras. This is a constraint rather than a chain: an object hung between two parents sits between them and follows both.

Removing the primary parent promotes one of the extras rather than orphaning the child.

Cycles are refused at the point of assignment: an object cannot be made to parent itself, directly or around a loop of any length, across any of its parent paths. Should a file ever present a cyclic graph, every walk is guarded and treats the cyclic child as a root, so nothing hangs.

Null objects#

A null is a transform with no content. It exists to be animated and to be parented to — a handle that carries other things.

A null's transform is a first-class animatable owner: it carries a full Transform section, without Opacity, and every property on it keys like any other. Nulls sit in the row tree after the ungrouped layers.

Deleting a null — long-press its row, then Delete <name> — removes it completely: its cel track, its base transform, every channel on it, and every parent link that pointed at it.

The motion path#

An animated Position draws its path in the viewport, so the arc is visible where the drawing is rather than only as a curve on the graph.

The path appears only when all of the following hold: the layer is the active layer, it is a plane layer, its Position channel is animated, and that channel has at least two keys at different frames.

• The path draws as a 2 pt amber polyline in world space, running from the first key to the last, sampled every frame — so its shape is the eased motion, not a straight line between keys.
• Each keyframe is marked with a white cross.

The transform gizmo's anchor is hit-tested before the motion path, so when a position key sits under the anchor the anchor wins.

Transform drivers#

A driver makes one object copy part of another object's transform, live, without parenting it.

Sources are read before their own drivers are applied, so two objects driving one another cannot recurse, and an object cannot drive itself.

See also#