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When you begin to lay out a composition, it’s a good idea to start by creating a static
layout of your project that represents how it looks at the beginning, end, or at a particular
moment in time. In addition to manipulating the geometry of layers in your project, you
can also alter their opacity to adjust how overlapping elements of your layout merge
together. Blend modes provide further control over the appearance of overlapping layers,
accentuating or stylizing the colors of the topmost layers based on the colors of underlying
layers.
After you create an initial layout, you can animate the layers you’ve added to set your
project in Motion. For more information about animating layers and their properties, see
Keyframing in Motion.
Group and Layer Order
In the Motion interface, every project is visually represented by a Project object at the
top of the Layers list. Beneath the Project object are the groups, image layers, and effects
objects that make up your project. Except for cameras, lights, and rigs, all layers and
objects in the Layers list must live inside a group.
In a purely 2D project, the order in which layers and groups appear in the Layers list
(known as the layer order) determines which image layers appear in front of others in the
Canvas. Before you use the tools described in this chapter, you should arrange the layers
and groups in your project so they appear in the proper order. For information about
layer order, see Reorganizing in the Layers List.
Objects and Layers
In Motion, any element that appears stacked in the Layers list (and Timeline) can be
referred to as an object. Objects encompass the entire range of images, effects, video
clips, audio clips, lights, cameras, and other items that combine to form a finished
composite. A layer is a special class of object defined as any image-based element—a
movie clip, a still image, a shape, text, a particle system, a replicator, and so on—that
is visible in the Canvas. Therefore, a rotating a triangle shape is a layer, but the behavior
object that animates it is not; a sepia-tone video clip is a layer, but the Sepia filter that
makes it so warmly old-timey is not. In the Motion documentation, the term object is
often used to describe the superset of all manipulable elements that act upon and form
a composition. Layer, however, always refers to the image-based elements acted upon.
Arrangement Commands in the Object Menu
As an alternative to rearranging layer order in the Layers list, you can change layer order
using commands in the Object menu. The Object menu commands are useful when you
want to move a layer to the front of your composition while you’re working in the Canvas.
259Chapter 7 Basic Compositing