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>
Design document for a new generator that produces full-length, non-story
music videos from a track alone, with no sourced footage.
Core decisions:
- Deterministic engine: audio is analyzed up front into a frame-indexed
feature table, so realtime preview and offline export render from the
same code path and produce the same frames.
- Whole-song analysis enables lookahead, so builds can anticipate drops.
- Scenes declare their parameters in a schema, which drives uniform
binding, generated UI, seeded per-track variation and arc automation.
- Hybrid compositor: fragment-shader and three.js layers in one stack.
- Preview is a first-class surface with section jumping, live param
editing and segment test-renders.
- Forked from party-stage by copy, then fully detached.
Includes per-phase gates and the validation tooling they depend on.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
