Make the view transform an operation the photographer can set

FR-DEV-3j gives the view transform two controls, contrast and the white point in stops above middle grey, persisted and held per mask layer like any other setting. A scene-referred pipeline whose white point cannot be moved hands the photographer a shoulder they cannot place. `view_transform` is a hand-written node in `Stage::View`, a new stage the composer emits last and emits whatever the node's state: a neutral operation is otherwise left out of the shader, but a photograph with no view transform is a scan. "Active" keeps meaning "moved from the defaults", so an untouched photograph writes nothing for it and `every_node_starts_neutral` still holds. A caller whose chain holds no view operation gets a default one. The composer's loop becomes an ordered list of steps — camera nodes, the matrix, scene nodes, layer-only nodes, the view — so each is emitted in exactly one place. The base curve could not be a node because it belonged to the camera; the ops README records why that argument went with it (D19). The panel shows it in the Light group as "Tone Mapping". Tests that counted the blocks of a neutral graph now count one, the view transform, and the two chain-wide tests that load a film expect the view transform to be absent, since a stock replaces it.
2026-09-27 16:52:54 -04:00
parent 37a6d99dc4
commit 92afaebd34
11 changed files with 386 additions and 99 deletions
@@ -74,6 +74,7 @@ pub mod distortion;
 pub mod film_sim;
 pub mod local_contrast;
 pub mod noise_reduction;
+pub mod view_transform;
 pub mod vignetting;

 pub use aberration::Aberration;
@@ -87,6 +88,7 @@ pub use film_sim::{FilmSim, FilmTables, PaperTables};
 // documentation for why that is two nodes and not one.
 pub use local_contrast::{Clarity, Texture};
 pub use noise_reduction::NoiseReduction;
+pub use view_transform::ViewTransform;
 pub use vignetting::Vignetting;

 // The declared nodes, plus `helpers` and `chain`. Generated into OUT_DIR by