# Objective
Animation docs could use some clarification regarding:
- how exactly curves are evaluated
- how additive blend nodes actually work
## Solution
Add some documentation that explains how curve domains are used and how
additive blend nodes treat their children.
## Commentary
The way additive blend nodes work right now is a little bit weird, since
their first child's weight is ignored. Arguably this makes sense, since
additive animations are authored differently from ordinary animations,
but it also feels a bit strange. We could make the first node's weight
actually be applied, and the present behavior would be recovered when
the weight is set to 1.
The main disadvantage of how things are set up now is that combining a
bunch of additive animations without a base pose is pretty awkward (e.g.
to add them onto a base pose later in the graph). If we changed it, the
main downside would be that reusing the same animation on different
parts of the graph is harder; on the other hand, the weights can be
locally reassigned by using blend nodes with no other children, which
rectifies this shortfall.
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