Apple Motion 2 - Manual (Page 268)

268 Chapter 3 Basic Compositing
Behind
The Behind blend mode forces the object to appear behind all other objects and layers,
regardless of its position in the Layers tab and Timeline.
If multiple objects or layers are set to Behind, they appear behind all other layers that
are not set to Behind, in the order in which they appear in the Layers tab.
Alpha Add
The Alpha Add blend mode works similarly to the Add blend mode, but instead of
adding the color channels of overlapping objects, it adds their alpha channels together.
Try using this blend mode instead of Motion’s default method of alpha channel
compositing for a different treatment of overlapping areas of translucency.
Premultiplied Mix
The Premultiplied Mix blend mode is intended for compositing images that are
premultiplied, such as those generated by 3D modeling and rendering software.
Premultiplied Mix is useful for images with translucent lighting effects such as lens
flares, volumetric lighting, fog and haze effects, and so on.
Limiting the Effect of Stencil and Silhouette Blend Modes
Whenever you use the Stencil or Silhouette blend modes in a layer that is set to the
Combine blend mode, the resulting effect carries down through every object in every
layer that lies underneath it in the Layers list. This is powerful, but not very useful,
since it prevents you from placing a background layer to fill the transparent area.
You can limit the Stencil or Silhouette blend mode’s effect to only those objects that
are within the same enclosing layer by setting the layer’s blend mode to anything
other than Combine.
For example, if you set the enclosing layer of the two objects in the Silhouette Alpha
example to Normal, then add a layer underneath containing additional objects, those
objects show through the transparent areas created by the Silhouetted layer.
01112.book Page 268 Sunday, March 13, 2005 10:36 PM