Motion Shadows overview
Motion projects that include point lights or spot lights can create more natural, realistic effects by casting shadows. Shadows are created when an opaque or semi-opaque object (a layer or group) blocks light from hitting another object. To see a shadow in Motion, you need at least three things: A shadow-casting light source, an object to cast a shadow, and another object upon which the shadow is cast. Multiple lights cast multiple shadows that may or may not be visible depending on the relative positions and settings of the objects in the scene.
Note: Ambient lights do not cast shadows.
In Motion, you can control whether a light source creates shadows and whether each object in the scene receives shadows or casts shadows (or both). You can even have an invisible object cast a shadow. The strength, sharpness, shape, and position of the shadow depends on the type and positions of the lights and relative position of all three objects.
WARNING: Some changes you make to 3D objects cause shadows to disappear. This occurs when the change causes rasterization of the 3D object—adjusting the opacity of a group or turning on the glow attributes for a text layer, for example. Flattening the 3D group allows it to cast shadows again. For more information about disappearing shadows, see Shadows and rasterization.
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 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 Add a drop shadow to a layer.