Layers

Common Properties

Layer

Common properties for all layers

Composition Diagram for Layer

Attribute	Type	Title	Description
`nm`	`string`	Name	Human readable name, as seen from editors and the like
`hd`	`boolean`	Hidden	Whether the layer is hidden
`ty`	`integer`	Type	Layer Type
`ind`	`integer`	Index	Index that can be used for parenting and referenced in expressions
`parent`	`integer`	Parent Index	Must be the `ind` property of another layer
`ip`	`number`	In Point	Frame when the layer becomes visible
`op`	`number`	Out Point	Frame when the layer becomes invisible

The ty property defines the specific layer type based on the following values:

`ty`	Type
`0`	Precomposition Layer
`2`	Image Layer
`3`	Null Layer
`1`	Solid Layer
`4`	Shape Layer
`None`	Unknown layer types

Visual Layer

Layer used to affect visual elements

Composition Diagram for Visual Layer

Attribute	Type	Title	Description
`nm`	`string`	Name	Human readable name, as seen from editors and the like
`hd`	`boolean`	Hidden	Whether the layer is hidden
`ty`	`integer`	Type	Layer Type
`ind`	`integer`	Index	Index that can be used for parenting and referenced in expressions
`parent`	`integer`	Parent Index	Must be the `ind` property of another layer
`ip`	`number`	In Point	Frame when the layer becomes visible
`op`	`number`	Out Point	Frame when the layer becomes invisible
`ks`	Transform	Transform	Layer transform
`ao`	0-1 `integer`	Auto Orient	If 1, the layer will rotate itself to match its animated position path
`tt`	Matte Mode	Matte Mode	Defines the track matte mode for the layer
`tp`	`integer`	Matte Parent	Index of the layer used as matte, if omitted assume the layer above the current one
`masksProperties`	`array` of Mask	Masks	Optional array of masks for the layer.

Parenting

Layer parenting offers a way to connect layers such that the movement of one layer (child) follows the movement of another (parent). Multiple child layers can reference the same parent (this is useful for applying the same transform animation to a group of layers).

When the parent property points to another layer, the referencing layer's current transformation matrix (CTM) is composed with the parent CTM:

C T M (c h i l d) = C T M (p a r e n t) \times T r a n s f o r m (c h i l d)

Parenting is transitive, and reference cycles are not allowed (undefined behavior).

Hidden Layers

The hidden flag hd determines whether a layer is rendered: hidden layers are not rendered as part of the normal layer tree, but their properties and content are evaluated when used as a reference target in other contexts.

Specifically, hidden layers

contribute to a layer's total transform when used as a parent
contribute to a layer's track matte when used as a matte source

hd only affects the layer for which it is defined, it does not transitively apply to other referencing layers.

Mattes

A matte allows using a layer as a mask for another layer.

The way it works is the layer defining the mask has a tt attribute with the appropriate value. The layer being masked is indicated by the tp attribute, which has the index (ind) of the layer that is being masked.

In this example there's a layer with a rectangle and a star being masked by an ellipse:

Example

Enable Matte
Matte Mode

Layer types

Shape Layer

Layer containing Shapes

Composition Diagram for Shape Layer

Attribute	Type	Title	Description
`nm`	`string`	Name	Human readable name, as seen from editors and the like
`hd`	`boolean`	Hidden	Whether the layer is hidden
`ty`	`integer` = `4`	Type	Layer type
`ind`	`integer`	Index	Index that can be used for parenting and referenced in expressions
`parent`	`integer`	Parent Index	Must be the `ind` property of another layer
`ip`	`number`	In Point	Frame when the layer becomes visible
`op`	`number`	Out Point	Frame when the layer becomes invisible
`ks`	Transform	Transform	Layer transform
`ao`	0-1 `integer`	Auto Orient	If 1, the layer will rotate itself to match its animated position path
`tt`	Matte Mode	Matte Mode	Defines the track matte mode for the layer
`tp`	`integer`	Matte Parent	Index of the layer used as matte, if omitted assume the layer above the current one
`masksProperties`	`array` of Mask	Masks	Optional array of masks for the layer.
`shapes`	`array` of Graphic Element	Shapes	Shapes

Image Layer

Layer containing an image

Composition Diagram for Image Layer

Attribute	Type	Title	Description
`nm`	`string`	Name	Human readable name, as seen from editors and the like
`hd`	`boolean`	Hidden	Whether the layer is hidden
`ty`	`integer` = `2`	Type	Layer type
`ind`	`integer`	Index	Index that can be used for parenting and referenced in expressions
`parent`	`integer`	Parent Index	Must be the `ind` property of another layer
`ip`	`number`	In Point	Frame when the layer becomes visible
`op`	`number`	Out Point	Frame when the layer becomes invisible
`ks`	Transform	Transform	Layer transform
`ao`	0-1 `integer`	Auto Orient	If 1, the layer will rotate itself to match its animated position path
`tt`	Matte Mode	Matte Mode	Defines the track matte mode for the layer
`tp`	`integer`	Matte Parent	Index of the layer used as matte, if omitted assume the layer above the current one
`masksProperties`	`array` of Mask	Masks	Optional array of masks for the layer.
`refId`	`string`	Reference Id	ID of the image as specified in the assets

Null Layer

Layer with no data, useful to group layers together

Composition Diagram for Null Layer

Attribute	Type	Title	Description
`nm`	`string`	Name	Human readable name, as seen from editors and the like
`hd`	`boolean`	Hidden	Whether the layer is hidden
`ty`	`integer` = `3`	Type	Layer type
`ind`	`integer`	Index	Index that can be used for parenting and referenced in expressions
`parent`	`integer`	Parent Index	Must be the `ind` property of another layer
`ip`	`number`	In Point	Frame when the layer becomes visible
`op`	`number`	Out Point	Frame when the layer becomes invisible
`ks`	Transform	Transform	Layer transform
`ao`	0-1 `integer`	Auto Orient	If 1, the layer will rotate itself to match its animated position path
`tt`	Matte Mode	Matte Mode	Defines the track matte mode for the layer
`tp`	`integer`	Matte Parent	Index of the layer used as matte, if omitted assume the layer above the current one
`masksProperties`	`array` of Mask	Masks	Optional array of masks for the layer.

Solid Layer

Solid color, rectangle-shaped layer

Composition Diagram for Solid Layer

Attribute	Type	Title	Description
`nm`	`string`	Name	Human readable name, as seen from editors and the like
`hd`	`boolean`	Hidden	Whether the layer is hidden
`ty`	`integer` = `1`	Type	Layer type
`ind`	`integer`	Index	Index that can be used for parenting and referenced in expressions
`parent`	`integer`	Parent Index	Must be the `ind` property of another layer
`ip`	`number`	In Point	Frame when the layer becomes visible
`op`	`number`	Out Point	Frame when the layer becomes invisible
`ks`	Transform	Transform	Layer transform
`ao`	0-1 `integer`	Auto Orient	If 1, the layer will rotate itself to match its animated position path
`tt`	Matte Mode	Matte Mode	Defines the track matte mode for the layer
`tp`	`integer`	Matte Parent	Index of the layer used as matte, if omitted assume the layer above the current one
`masksProperties`	`array` of Mask	Masks	Optional array of masks for the layer.
`sw`	`integer`	Width	Solid rectangle width
`sh`	`integer`	Height	Solid rectangle height
`sc`	Hex Color	Color	Solid fill color

Precomposition Layer

Layer that renders a Precomposition asset

Composition Diagram for Precomposition Layer

Attribute	Type	Title	Description
`nm`	`string`	Name	Human readable name, as seen from editors and the like
`hd`	`boolean`	Hidden	Whether the layer is hidden
`ty`	`integer` = `0`	Type	Layer type
`ind`	`integer`	Index	Index that can be used for parenting and referenced in expressions
`parent`	`integer`	Parent Index	Must be the `ind` property of another layer
`ip`	`number`	In Point	Frame when the layer becomes visible
`op`	`number`	Out Point	Frame when the layer becomes invisible
`ks`	Transform	Transform	Layer transform
`ao`	0-1 `integer`	Auto Orient	If 1, the layer will rotate itself to match its animated position path
`tt`	Matte Mode	Matte Mode	Defines the track matte mode for the layer
`tp`	`integer`	Matte Parent	Index of the layer used as matte, if omitted assume the layer above the current one
`masksProperties`	`array` of Mask	Masks	Optional array of masks for the layer.
`refId`	`string`	Reference Id	ID of the precomp as specified in the assets
`w`	`integer`	Width	Width of the clipping rect
`h`	`integer`	Height	Height of the clipping rect
`sr`	`number`	Time Stretch	Time Stretch
`st`	`number`	Start Time	Start Time
`tm`	Scalar	Time Remap	Timeline remap function (frame index -> time in seconds)

Time Stretch

The st property specifies a start time offset, while sr defines a time stretch factor, to be applied when evaluating animated properties pertaining to the layer:

t' = \frac{t}{s t r e t c h} - s t a r t

sr values less than $1$ increase the layer playback speed, while values greater than $1$ decrease it ("stretching" the layer timeline).

Example

Time Stretch 

Time Remap

The tm property specifies a time remap function as an animatable property, allowing full control over the precomp timeline (subset, speedup/slowdown, reverse, frame-freeze, or any other arbitrary transformation).

It maps the current layer time (in the frame index $[i p \dots o p]$ domain) to a precomp time expressed in seconds, and evaluates all animatable precomp properties based on the new time value:

t m : [i p \dots o p] \mapsto s e c o n d s

t' = t m (t) \cdot F P S

Note: the global frame rate factor $F P S$ (Animation fr property) is required to convert back into the frame index domain.

When both time stretch (sr) and time remap (tm) are specified, time stretch is applied first.

Example

Time Remap 

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