# A hand-written node. `rust:` names the type in `crate::ops` that implements
# `Operation`; its descriptor, its parameters and its passes come from that
# type rather than from this file.
#
# It appears here anyway so that `ops/` lists the whole pipeline in order —
# including the neighbourhood operations, which run as a group after every
# point operation but are still ordered among themselves.
id: noise_reduction
order: 110

attributes: [detail]
rust: NoiseReduction

why_rust: |
  A kernel, not four facts. The declarative schema hands a fragment a colour
  and no coordinate, which is precisely what a denoiser cannot work with — it
  is defined by what the neighbouring pixels are doing. It is therefore a
  `DetailStage` (see `../src/detail.rs`), which means deciding at every render
  how many dispatches to emit, converting a radius stated in *source* pixels
  into the render pixels this frame is being drawn at, and declaring the halo
  the tile scheduler needs. None of that is expressible as a uniform
  expression, and stretching the schema to cover it would produce a worse
  language than Rust aimed at one caller.

placement: |
  First among the detail operations, because denoising is a repair and
  everything else in this stage is an enhancement: sharpening or adding
  clarity to a noisy frame amplifies the grain along with the detail, and no
  later pass can separate them again. Its position relative to the point
  operations is not this number's to decide — the whole detail stage runs
  after the fused pass, in linear light, before the output transform.