Game Development Reference
Green to Source drop down or to Blue to use the blue channel of
the leaves layer to create the green channel of the current layer
(Fig. 5.55 ).
Figure 5.55 The result of using
an additional layer to create the
If at this point you're scratching your head, wondering how
this could ever come in handy, I'm right there with you. It's an
interesting facility, but I only see it being helpful in creating weird
blends of layers.
I should point out that you can use the current layer as the
source layer, which means that you can also mix and match chan-
nels. This essentially turns the Set Channels effect into the Shift
Channels effect. There is an interesting example using the Shift
Channels effect later in this chapter that you may want to see.
The Set Matte Effect
The Set Matte effect is similar to the Set Channels effect, only that
the Set Matte effect allows you to use the alpha channel of another
layer as the alpha channel of the current layer. The After Effects
help documentation suggest that this effect is obsolete; replaced by
the alpha and track matte options in the Timeline panel. However,
I think this effect is viable for two reasons. First, it allows you to use
any layer in the composition as a matte, as opposed to mattes in
the Timeline panel, which require that matte layers be adjacent to
the layer they're masking. This effect is also viable because it allows
you to use other attributes from another layer—not just the alpha
channel. If you do a lot of work with luma or alpha mattes, this
effect can open up all new doors of possibility for you.