# A hand-written node. `rust:` names the type in `crate::ops` that implements
# `Operation`; everything else about it — its descriptor, its parameters, its
# WGSL — comes from that type rather than from this file.
#
# It appears here anyway so that `ops/` lists the whole pipeline in order.
# A chain half-declared here and half-ordered in Rust would be worse than
# either alone: the order is the one thing a reader comes to this directory
# to learn.
id: tone_curve
order: 60
rust: ToneCurve

why_rust: |
  Five control points presented as one curve widget, with an interpolator and
  a monotonicity guarantee behind it. Its neutral is a *relationship* between
  parameters rather than a set of values — the identity diagonal — which is
  not something the declarative `active:` rule can express, and its
  `presentation()` spans parameters rather than describing one.

placement: |
  After the fixed-weight region controls, so the curve is the final word on
  tone: a photographer reaches for it to fix what those controls could not
  place exactly.