89e05459c0
A section used to be one scene, and two thirds of the library is composable —
sparse by design, elements ON something. Cast as backgrounds anyway, they left
9 of 40 sampled frames under 20% painted, the darkest at 0.3%: a minute and a
half of a few bright things on black, invisible to every gate because every
gate on the stack was a limit rather than a floor.
Every section now stands on a GROUND: a canvas that fills the frame, cast per
section kind so a shot cut changes the shot and not the world. When the shot
fills the frame itself it IS the ground — two canvases stacked is two pictures
fighting. Above that, a coverage BUDGET: director appetite times the section's
energy times where the story is, capped at two frames' worth of material.
The measured facts move into the repo. scenes/metadata.json is generated from
the gallery — coverage as a shot, coverage as a bed, variety, the structural
profile — tracked in git, stamped with a fingerprint of the scenes and the
metric definitions, and refreshed from gallery.html. `surface` is derived from
it rather than declared; nine scenes claimed `canvas` while painting under a
third of the frame, and declaring it is now a lint error. The generator weights
every layering choice by measured structural distance, because family labels
and the render disagree: two `geometric` scenes can be 0.31 apart and a `flow`
and an `organic` scene 0.04.
The gallery's 0.1 red line is gone. It was right when a section was one scene
and wrong now — nineteen scenes were failing a bar for being consistent, which
is a virtue in an ingredient.
Chasing the numbers turned up four real faults:
* A scene that reads prev() cannot be a ground. It returns the whole
composited frame including the layers above it, so a datamosh under a shot
is eating it: the render stopped reproducing from a seek and two WebGL
contexts diverged by 91/255 against a tolerance of 4.
* Screen was the wrong operator for a shot over a bed. It lightens, so a
median quarter of every frame clipped to paper and whole sections rendered
100% white. Replaced by a lumakey — the shot's brightness is its alpha.
* Feedback was an accumulator: a still image settled at 2.3x its own
brightness. Fine over black, fatal over a filled ground. Normalised at 0.6,
plus a highlight shoulder so the top rolls off instead of clipping.
* useTrack never prewarmed, so a fresh Show's first frame differed from every
later render of it — the export-breaking hazard Compositor.prime documents.
Blazing is a decision now, not a side effect: directors declare an appetite for
it, a section must be loud and late in the story to earn one, and quiet kinds
never do. The ceiling gate matches that — a hard cap per section, and no more
than a fifth of them hot at all.
Rendered across twelve videos, middle of every section:
painted 51% mean, darkest 0.3% -> 87% mean, darkest 43%
clipped white 24% median, worst 100% -> 1% mean, worst 30%
separation 0.10 -> 0.44
Seven scenes can ground a section — five geometric, two organic — so every
quiet section of every video stands on one of two beds. That is the library's
largest hole and it is scene work: there is no minimal or flow canvas that
fills half the frame without reading prev().
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
79 lines
3.0 KiB
JavaScript
79 lines
3.0 KiB
JavaScript
// Flow family: curtains of light standing above the track's horizon.
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//
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// Distinct from Curl Flow (a full-frame advected field) and Silk Ribbon (one
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// strand): this is several tall vertical sheets, each rippling on its own phase,
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// dense at the base and dissolving upward. The rippling is a sum of sines rather
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// than noise, which is what gives an aurora its folded-sheet look instead of a
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// smoky one — noise curtains read as fog.
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//
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// The horizon is the track's, so this stands in the same place as every other
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// scene that has ground.
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export const auroraVeil = {
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name: 'Aurora Veil',
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family: 'flow',
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kind: 'fragment',
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consumes: ['ink'],
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traits: ['camera', 'space', 'style'],
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params: {
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curtains: { type: 'int', range: [2, 9], default: 4, uniform: 'u_curtains', bias: 'density' },
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height: { type: 'float', range: [0.4, 1.8], default: 1.0, uniform: 'u_height' },
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fold: { type: 'float', range: [0.1, 1.4], default: 0.55, uniform: 'u_fold', bias: 'density' },
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speed: { type: 'float', range: [0.03, 0.5], default: 0.15, uniform: 'u_speed', bias: 'motion', rate: true },
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ground: { type: 'float', range: [0, 0.8], default: 0.3, uniform: 'u_ground' },
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palette: { type: 'palette', count: 5 },
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},
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reactive: {
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fold: { feature: 'bandLow', amount: 0.3, response: 'smooth' },
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},
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shader: `
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vec4 scene(vec2 uv, vec2 p) {
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float t = u_time * u_speed + u_seed;
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p = sigCamera(p);
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float horizon = sigHorizonY() * 0.8 - 0.55;
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float above = p.y - horizon;
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vec3 col = pal(0) * 0.06;
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for (int i = 0; i < 9; i++) {
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if (i >= u_curtains) break;
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float fi = float(i);
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float s = u_seed + fi * 37.13;
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// Each sheet is a vertical line whose x wanders as a sum of three sines.
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// Three is the fewest that stops reading as a single wobble.
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float x = (fract(s * 0.61) - 0.5) * 2.2
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+ sin(above * 1.7 + t * 1.3 + s) * u_fold * 0.35
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+ sin(above * 3.1 - t * 0.8 + s * 1.7) * u_fold * 0.18
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+ sin(above * 0.7 + t * 0.4 + s * 2.3) * u_fold * 0.5;
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float d = abs(p.x - x);
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float widthAt = 0.05 + above * 0.06 + u_sigLine * 0.05;
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// Bright and tight at the base, wide and faint at the top: the vertical
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// falloff is what makes it a curtain rather than a stripe.
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float rise = smoothstep(-0.05, 0.0, above) * exp(-max(above, 0.0) / max(u_height, 0.05));
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float sheet = exp(-d * d / max(widthAt * widthAt, 1e-5)) * rise;
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vec3 tint = palRamp(fract(s) * 0.5 + above * 0.12 + 0.1);
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col += tint * sheet * (0.55 + 0.5 * 0.6);
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}
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// Ground: the curtains reflected, dim and compressed.
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if (u_ground > 0.01 && above < 0.0) {
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float below = -above;
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col += pal(2) * u_ground * exp(-below * 6.0) * 0.35;
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}
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col = sigAir(col, p, smoothstep(0.0, 1.6, abs(p.x)));
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return vec4(inkValue(col), 1.0);
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}
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`,
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};
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export default auroraVeil;
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