Revisiting the framing layer turned up that it was not reaching four of the
forty-two scenes, and that none of its gates could have told us.
Those gates check the PLAN — cue sizes, the distribution of shot sizes across
a population, headroom, seek determinism — and a plan that never reaches the
image passes every one of them. Rendered at wide, normal and close, Scan
Tear, Pylon Grid, Pitch Shatter and the 3D Particle Field came back
byte-identical at every size.
The cause was a category error in the first implementation. Framing was
applied inside sigCamera, which is gated on the `camera` personality trait —
so a scene that declined the track's drift and sway silently declined the
shot size as well. That gating is right for a TRAIT and wrong for framing,
which is not one: framing is where the camera is standing for this shot, and
no scene should be exempt from it because of an unrelated art-direction
decision.
- Framing now lives in the shader epilogue, applied to the coordinate every
fragment scene is handed, so honouring it is not optional. uv is left
unframed on purpose: it is screen space, and prev() and sigGrain belong to
the output image rather than to the scene being filmed.
- Scan Tear and Pitch Shatter build their image from uv deliberately — a
signal artefact happens to the signal, not to the world behind it. They now
slice on raw uv and build the field they displace from a new framedUv(p),
so the tear stays locked to the frame while the imagery behind it is filmed
wide or close.
- Particle Field receives framing in update() and honours it as a camera
dolly, which is what framing literally is when a layer has a real camera.
Distance divided by scale, matching the fragment path where the coordinate
is divided by it.
New gate renders instead of inspecting: 42 of 42 scenes now respond to
framing, weakest Ridge Terrain at 0.22 of its own brightness, against a 0.05
floor. Also drops a stale comment on Layer.setFraming that still claimed
sigCamera applied it.
105/105 checks pass including the slow set.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Both phases come out of the manual gate — watching whole tracks — and both
fix something no automated check was looking for.
Phase 8: shots. A section is a STAGE of the song and can run ninety
seconds; one scene held that long reads as a still image with a wobble on
it. Each section kind now gets a roster of three or four stage visuals
instead of one scene, and each section is cut into shots that rotate
between them on phrase lines, never holding past 22s. The roster stays per
kind, so a track's drops still cut between the same images and the video
keeps its identity; the anchor opens each section and the rotation returns
to it, and when a companion is due it is the least recently shown one.
The arc driver stopped working in sections and started working in cues, one
per shot, so a shot cut and a section change take the same code path and
differ only in transition length. The default transition is a slow
dissolve — two bars calm, one loud; a straight cut is reserved for
sections above the energy threshold, because on calm material a cut reads
as a glitch rather than as an edit.
Phase 9: production design. With cuts every fifteen seconds the next
problem was that the images being cut between shared nothing but the
palette. What a music video actually shares across shots is a location, a
cast, a camera operator and an art direction, so each track now generates a
personality in four traits (shape, camera, space, style) off the look seed.
The traits reach shaders as uniforms plus four helpers in the contract, and
each scene expresses them its own way: Classic Wave's rings take the
signature polygon, Metaballs merge as one, Floating Geometry no longer
picks between a box and a circle because the production already decided.
The part that makes it a design rather than a filter: scenes DECLARE which
traits they honour, a track is built on one or two, and a scene that does
not honour all of them is not cast in that track. The library shrinks per
track on purpose.
Two gates keep the declaration honest — lint greps each shader for evidence
of every trait it claims, and a render check measures that each declared
trait actually moves the image (41 scene/trait pairs, weakest response 64
of 255). A layer with no personality renders bit-identically to before,
which is what keeps every earlier sweep and regression valid.
Checks changed rather than added:
- P4 scene-change and drift checks now measure per shot, not per section;
the crossfade check reads its length off the cue.
- P5 flash sweep runs per shot, so the visuals that only appear
mid-section are measured too.
- P6 preview/export parity primes first (as both real paths do) and
compares at the one-LSB tolerance Phase 7 already uses. Measured over
four consecutive shows: 3 frames at delta 1, then bit-exact — GPU
variance on first render, not a divergence.
- P2's contract-uniform list is derived from the contract instead of
retyped, so the signature uniforms cannot fall out of sync.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Engine core: Timeline (fixed dt, audio-mastered in realtime), seeded Rng,
Renderer, Layer/ShaderLayer/SceneLayer, Compositor with blend modes,
feedback and post chain.
Shader scenes are compiled against a fixed uniform contract and define only
`vec4 scene(vec2 uv, vec2 p)`, so adding a scene costs a shader plus a
params block. Deep Nebula ported from party-stage as the first one.
Gate passes, 7/7 in checks.html:
- 300 frames rendered twice are bit-identical
- a fresh Engine reproduces the same frames
- simulated dropped frames change nothing (proves dt is fixed)
- seek matches sequential playback
- 320x180 vs 1280x720 agree within 0.010 (limit 0.06)
- seeded rng reproducible, forked streams independent
- compositor reset clears feedback history
Static gates: no wall-clock or unseeded randomness in deterministic
directories; scene schemas and shader sources agree in both directions.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
