Watching several finished tracks side by side turned up the problem neither
Phase 8 (too few cuts) nor Phase 9 (no through-line) addressed: the same
scene cast in two different videos looked like the same footage twice.
Section bias is nearly identical between two tracks' drops, so both sampled
their parameters around the same centre, and the library's own averageness
did the rest.
Three answers, none of them a new scene:
Temperament — a per-track hand on every parameter dial: intensity, pace,
detail, and an extremity that decides how far toward the ends of a range
the track is willing to sample. Bias comes from the section and is shared
between tracks; temperament comes from the track and is not.
Overlays — sometimes a second full scene composited over the shot, from a
different family, in a blend that preserves what is underneath and never
above 0.6 opacity. Not always: a stack that always doubled up would read
as permanently cluttered rather than as occasionally layered.
A wider palette — hue now derives from SPECTRAL TILT, the log ratio of
treble to body. The centroid is a number most masters sit in the middle
of, and the plain body/(body+treble) fraction is worse: low frequencies
carry most of the energy in all music, so it read 0.98-1.00 for
everything and four different battery tracks came out within 0.02 of
each other. The ratio is multiplicative, so its logarithm is what
spreads — the same four measure -9.3, -5.0, -4.1, -3.8. Also both ways
round the wheel (violet, magenta and pink were unreachable by
construction), four new schemes, and seeded chroma profile and lightness
curve. Closest battery pair went from 0.005 to 0.113.
Twelve scenes take the library to 36, six per family: Aurora Veil, Vortex
Drift, Tide Rings, Ink Bleed, Dust Chamber, Salt Flat, Cargo Belt, Gate
Corridor, Circuit Bloom, Truchet Fold, Signal Decay, Storm Rift. Weighted
toward the 'space' and 'shape' traits, which were thinnest and so the
signatures most likely to run a track out of cast — the Phase 9 casting
rule means the pool a track draws from is smaller than the library.
Also fixes a real one in shots.js: heavy LRU weighting was not enough to
make a section reach its whole roster, and a five-shot section still came
out 0,2,0,2,0 about a fifth of the time. An unseen companion now wins
outright; which one is still free, so only the coverage is guaranteed.
Block Mosh declared the camera trait, assigned sigCamera(p) to a p it then
never read, and passed the lint's evidence grep. The Phase 9 render gate
measured its response to the camera at exactly zero.
--- tooling ---
Adding a scene was mostly boilerplate and round-trips, which is expensive
in both senses. The irreducible cost is the shader body; everything around
it is now mechanical:
npm run new:scene -- "Name" --family=... --traits=...
writes the module, registers it, and leaves a skeleton that already passes
every gate, with name-derived constants so two skeletons are not twins.
The lint grew the rules that previously needed a GPU to catch: the dead
camera above, prev() with no base image, and large loops with no early
break (with a `// lint: fixed-cost` opt-out for a genuinely fixed-cost
sampling loop). checks.html?scene=Name runs the per-scene acceptance
battery for one scene — ten lines and a verdict instead of rendering the
whole library to find out whether one shader is alive. The same procedure
is a repo skill under .claude/skills/build-visualizer/.
--- checks changed, with the measurements ---
P5 determinism compared two WebGL CONTEXTS, which is not what it is for.
Measured: one context is bit-exact over 40 frames with feedback at 0.6;
two contexts disagree by up to 2/255 whether feedback is on or off. It now
asserts generation is byte-identical (hard) and rendering within 2/255,
since feedback compounds single-level variance.
P10's cross-track comparison measures distance RELATIVE to how much image
there is. Most scenes are mostly dark, so two genuinely different renders
— 25 bars against 53 — scored under 0.02 absolute purely because the black
background agrees with itself.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Three new scene shaders to widen the library, now that the main families are
settled. Each is a shader plus a params block, registered in the single
source of truth (scenes/registry.js), so casting, UI, arc and checks pick
them up automatically.
- Block Mosh (glitch): a datamosh. Blocks pull the feedback buffer along
per-block strokes on a bar-quantized grid so the corruption steps like an
edit rather than crawling, and spills on onsets. Fills the most iconic
gap in the glitch family.
- Neon City (structural): a receding skyline with instanced lit windows,
distinct from the rolling ridgelines and the road grid it sits alongside.
- Flora (organic): an abstract plant of swaying stalks, teardrop petals and
a bloom corona, all stamped in the track's signature shape.
Also adds HOWTO-visualizers.md, a quick reference for building the next one.
Ten new scenes, with 'minimal' first: the family was empty, so intros and
breakdowns fell through to flow/organic and every track opened at full
density. Quiet sections now land on a restful family 48/48 times across 24
seeds, 28 of them minimal.
New: Horizon Lines, Spectrum Sculpture, Slow Orb (minimal); Curl Flow
(flow); Plasma Bloom, Metaballs (organic); Kaleido Tunnel, Moiré Grid
(geometric); Ridge Terrain (structural); Scan Tear (glitch).
Four real bugs, three of which the existing gates could not have caught:
1. SHADER PROGRAMS LINK ASYNCHRONOUSLY. three.js uses
KHR_parallel_shader_compile, so draws against an unlinked program render
wrong. The heaviest scene had its first TEN frames differ from every
later render of the same frames. Preview hides this entirely; export
renders each frame once, so those frames would ship broken. Added
Engine.prime() — WebGLRenderer.compile() plus a discarded warm frame —
and the exporter now primes before encoding. Rendering a throwaway frame
and reading it back is NOT sufficient; measured, it left 3-5 frames wrong.
2. Moiré Grid declared a param on u_width, which the shader contract already
uses for stereo width. GLSL redefinition, and the only symptom was a
black frame. Lint now rejects any param uniform colliding with the
contract.
3. Spectrum Sculpture strobed at 4 flashes/s. Two causes: rotation measured
in turns meant bar-crossing frequency was bars x rate (82 bars put a
slow-looking 0.12 turns/s at 10 Hz), and hard band-tier boundaries made
every bar switch band simultaneously. Rotation is now in segment units so
the rate IS the crossing frequency, bands interpolate, and the range is
capped where the flash meter measures zero.
4. Particle Field was being chosen as a primary background despite being
mostly empty by design. Scenes now declare role: 'accent'; those are
never primary and are judged on variance rather than luminance.
Three checks were themselves wrong and were rebuilt: mean-distance metrics
unfairly fail sparse scenes for being tasteful rather than static, so
"animates" and "no duplicates" now use max channel delta.
PLAN.md §1 gains two refinements: programs must be primed before the first
frame, and even same-machine the heaviest shaders vary by one LSB under
differing GPU load — so the per-scene criterion is max delta <= 1 rather
than an identical hash. A real bug scores in the tens there.
Full suite 67/67 across all seven phases. Worst 4K frame 3.8ms,
worst flash rate 0/s, worst determinism delta 1/255. Adds README.md.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Multi-layer stacks with blend modes, feedback, post chain, and a 3D
particle layer proving the compositor is genuinely hybrid. Looks now
generate accent layers from a different family, composited additively at
low opacity, weighted by section energy so intros stay sparse.
Adds flash-rate safety (engine/flash.js), which was not in the original
plan and should have been. This generates beat-reactive video for
publication, and rapid light-dark cycling is the photosensitive-epilepsy
trigger; WCAG 2.3.1 caps it at three flashes per second. Classic Wave
measured 7-8/s at every output resolution from 96x54 to 1920x1080, so it
was a real hazard rather than a sampling artefact.
Root cause was general, not one bad shader: `u_time * u_speed` where speed
is reactively modulated. Phase is elapsed*rate, so changing the rate at
time T jumps phase by T*delta — sixty seconds in, a 0.05 wobble throws the
phase three whole units between consecutive frames, and it worsens as the
track runs. Fixed by introducing rate params:
- schema flag `rate: true` documents and marks them
- Layer.resolveParams skips reactivity on them
- ArcDriver skips drift on them
- validateModule rejects a reactive entry on one
- lint-scenes greps shaders for `u_time * u_X` and fails if X is unmarked,
so no future scene can reintroduce it
Every rate param across the six scenes is now marked. Two checks were
needed to find this: a per-look flash check, and a per-SCENE sweep at
aggressive params, since the look generator only samples part of the space
and a scene can hide an unsafe region for a long time.
Gate 10/10. Worst flash rate now 1/s. Feedback stable over 10,000 frames
(luminance 0.17-0.59, no saturation or decay). 0.17ms/frame at 1280x720.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
All five party-stage shaders now ported. Each declares its params
declaratively; uniform binding, UI controls, seeded sampling and arc
automation all derive from that one block, so a new scene costs a shader
and a schema and nothing else.
Port changes: LED-grid masks stripped, hardcoded colours replaced with
palette lookups, magic numbers lifted into params. Psychedelic Drift's
internal 15-second scene timer removed — keeping the visuals moving is the
arc driver's job, and it knows where the song's real transitions are.
ParamPanel generates controls from the schema alone and knows about no
specific scene; a hand-written control would be a bug.
Gate 8/8: schemas valid, uniforms accounted for in both directions, all
scenes compile and render, 128 range-sweep frames with no black, blown or
flat results, every param exposed in the UI, edits clamped, presets
round-trip and survive schema drift.
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>
