2 Commits

Include renames

Author	SHA1	Message	Date
dtourolleandClaude Opus 5	4a2fcb6d22	Render a film stock on the GPU, and let it take over the rendering ... The stock model landed in dr-film with no way to see it. This is the pipeline node, the two texture bindings it reads, and the end-to-end test that proves the shader agrees with the model. The design point is that a film simulation is not an adjustment. Every other node changes a picture; this one makes it. A stock's characteristic curve does the camera profile's base curve's job -- from measurements rather than from a curve somebody drew -- so running both renders the scene twice: the camera's rendering, and then a film's rendering of that. It looks like neither, and it reads as a colour-management bug with no colour-management bug to find. So `Operation::renders` is new. A node declaring it takes camera RGB and hands back linear sRGB, and the composer emits neither the base curve nor the conversion out of camera space. Both halves move together, and the composer keeps them as one string precisely so that getting half of it right is impossible. The tables are not parameters, for the reason vignetting's coefficients are not: they are measurements. dr-pipeline declares the layout as a plain struct and keeps its no-dependency property; the two crates share no types on purpose. `EditGraph::set_film_tables` offers them to every node rather than to the one that wants them, because knowing which concrete type is which is what the graph is organised not to know. Bindings 4 and 5 follow the masks precedent: declared unconditionally so one bind group layout serves every generated shader, bound to 1x1 placeholders when no stock is loaded. Both are interpolated by hand with textureLoad -- this pipeline binds no sampler, and adding one for two lookups would cost a binding in every shader. Uploads are keyed on content so an unchanged stock does not push half a megabyte across the bus per frame. The end-to-end test earned its place immediately: it found the density lookup being filled z-fastest while a 3D texture upload wants x-fastest, so the red and blue axes were transposed. Green matched exactly, which is what that bug looks like -- a plausible photograph of the wrong colour, and one that every unit test on either side of the seam passes. dr-film now pins the layout in a test that needs no device, and states it where the field is declared. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>	2026-08-25 15:12:56 +02:00
dtourolleandClaude Opus 5	b6a95e1965	Simulate a film stock from its measurements, not from someone's grade ... FR-DEV-3f asks for look emulation and proposes HaldCLUT import to inherit the free film-simulation ecosystem. This takes the other road for the stocks where the measurements exist: run the physics. A stock here is its manufacturer's own datasheet -- spectral sensitivity, characteristic curves, dye densities. Light exposes three emulsion layers, the layers develop to densities, the densities are dyes that absorb, and what is left is what reaches the eye. A colour negative comes out orange and upside down because that is what a colour negative is; it becomes a photograph when a paper profile prints it, with the enlarger's filtration solved rather than dialled. What that buys over a LUT is that the parameters stay physical. Opening up a stop moves the picture along the film's real characteristic curve, shoulder and all, instead of scaling a number baked at one exposure. The data cost runs the other way too: a stock is 17 kB of published measurements where one HaldCLUT is 800 kB of one person's grade. It looks like it needs a spectral integration per pixel. It does not, and that is the whole design: - Exposure is a 3x3 matrix. The reconstructed scene spectrum is linear in the sRGB triple, so the integral collapses into nine numbers, exactly -- no approximation. - The characteristic curve is three 1D functions, sampled exactly. - Everything after that -- dye absorption, the print through the negative, the paper, the viewing illuminant, the adaptation -- takes exactly three numbers in, so it bakes into one 32^3 lookup. Per pixel: a matrix multiply, three curve taps, one fetch. Splitting the curve out of the 3D lookup rather than baking one LUT over exposure is measured, not assumed: the curve carries the sharp shape and the dye mixing is smooth, so folding them together would need three times the resolution for the same error. At 32^3 the worst error is 0.003 in linear sRGB, under one 8-bit code value, and a test says so. No wgpu dependency, deliberately, and the same isolation argument dr-lens makes: the model is plain f32 with a documented layout, so every property worth asserting is asserted on the CPU. Binding it to a texture is dr-gpu's job and is not done here yet. The expected values in tests/ came from a Python prototype running against a different colour-science stack. Agreement to three decimals is evidence about the model rather than about one implementation of it -- a transposed matrix or a mispasted observer row would pass every unit test and fail that one. Profiles are converted from spektrafilm by Andrea Volpato, CC BY-SA 4.0. The converter is in the tree and runnable, so what was changed from upstream is auditable rather than taken on trust; profiles/CHANGELOG.txt records it, including the one deliberate deviation -- Mallett & Yuksel's 1 kB basis instead of Hanatos's 4 MB table, which costs accuracy at the gamut edge and saves four megabytes. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>	2026-08-25 14:44:54 +02:00