Apple Motion 5.1.1 - Manual (Page 945)

Chapter 21 3D compositing 945
Cast shadows versus drop shadows
There are two common types of shadow effects used in motion graphics work: drop shadows
and cast shadows. Motion can create both effects, but because they have different purposes
and applications, it may be helpful to consider the differences between them. Cast and drop
shadows simulate the effect of light blocked by an opaque object. But a cast shadow is a 3D
effect requiring a light source and an object for the shadow to fall upon, whereas a drop shadow
is a 2D effect simulating a cast shadow without a light source and therefore is limited to a very
small range of settings.
Drop shadow Cast shadow
Drop shadows are commonly used to simulate depth and separate foreground objects from
the background in 2D projects. The classic drop shadow effect is used on light-colored titles so
the text is legible against dark and light backgrounds. In a drop shadow effect, the imaginary
light source does not create any shading effect on the surface of the object, and the shadow’s
position is set at a fixed direction.
A drop shadow is rendered as a part of the foreground object, so it doesn’t interact with
background objects. However, because it is an effect, its appearance can be customized.
The softness, opacity, position, and color can be adjusted and animated without having to
manipulate a light source.
Cast shadows are true 3D effects, and their appearance is determined by the light source and the
other objects in the scene. Multiple cast shadows interact with each other and take their shapes
based on the surfaces and positions of the objects upon which they are cast.
This section addresses cast shadow effects. For information on drop shadows, see Drop shadows
overview on page 244.
Shadow controls
Shadows are controlled by adjusting settings in two places. Point and spot lights have a
Shadows section in the Light Inspector, and all visible objects have a Shadows section in the
Properties Inspector.
Note: 2D groups at the root level of the project do not have lighting or shadow controls. To
enable shadows on such a group, convert it to 3D or embed it in another 3D group.
Shadow Parameters in the Light Inspector
•
Shadows: This checkbox turns on Shadows controls. (When activated, the checkbox is
blue.) The Shadows checkbox lets you set some lights to cast shadows, and others not to
cast shadows.
Selecting this checkbox causes the light to cast shadows on objects in front of it if the objects
also have shadow controls enabled. Deselecting it exempts the light from generating shadows,
regardless of settings of individual objects.
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