Render Pipeline

Render Pipeline

To become an expert compositor is to precisely understand
the order in which actions are performed on an image,
also known as the render pipeline. For the most part render
order is plainly displayed in the Timeline and follows consistent
rules:
. 2D layers are calculated from bottom to top of the
layer stack.
. Layer properties (masks, effects, transforms, paint, and
type) are calculated from top to bottom (twirl down to
see the order).
. 3D layers are of course calculated based on distance
from the camera; coplanar 3D layers respect stacking
order and behave—relative to one another—like
2D layers.In a 2D composition, After Effects starts at the bottom
layer and calculates any adjustments to it in the order that
properties are shown, top to bottom. Then, it calculates
adjustments to the layer above it, composites the two of
them together, and continues up to the top layer of the
stack, while the properties of an individual layer render top
to bottom .


So, although effects within layers always calculate prior to
transforms, by applying an effect to an adjustment layer
above, you guarantee that it is rendered after the transforms
of all layers below it.
Track mattes (and blending modes) are applied last, after all
other layer properties (masks, effects, and transforms) have
been calculated, and after their own mask, effect, and transform
data are applied. Therefore, you don’t generally need
to pre-render a track matte just because you’ve edited it.
Optimize Previews and Renders
As I work, I organize portions of my master comp that I
consider fi nished into their own subcomps, and if they
require any render cycles at all, I prerender them. Failure
to commit to decisions—keeping options open—costs time
and effi ciency. It’s as true in After Effects as it is in life as a
whole.
Pre-rendering a subcomp does, however, lead to a decision
about what happens after you render it.