New "Modular" engine in a-immersive with three hot-swappable Faust
sub-engines (subtractive/additive/fm) sharing a common modulation pool:
16 ADSR slots + 32 LFO slots (single-knob sine->tri->square->saw
wavemorph) routed through a 48-source x 10-destination matrix per
engine. Per-connection scalar amounts in [-1, 1], summed at each
destination. Default MLP output count is 512 (32 mod-source params +
480 matrix cells); model reinits on sub-engine swap, count change, or
engine-param exposure toggle.
Faust layer:
- mod-pool.lib: shared ADSR/LFO/source-bus library
- gen-modular-dsp.py: byte-reproducible generator (source of truth)
- modular-subtractive: faithful Minimoog (3 osc, ladder filter, no envs)
- modular-additive: 64-partial, spectral shape + formants, no envs/LFOs
- modular-fm: 4-op matrix + self-feedback, no envs
- All three share d08=amp, d09=pan conventions
- MODULAR_DESTINATIONS.md: authoritative destination table
JS layer:
- ModularEngine: self-contained SynthEngine with getState/setState,
setSubEngine, setModSourceCount, setExposeEngineParam
- modular-ui: drawer with sub-engine toggle, ADSR/LFO count steppers,
per-slot enable switches, matrix grid editor (tap-cycle, long-press
precise, right-click menu, negative amounts), preset overlay
- modular-presets: 6 named presets (Slow pad, Plucky bass, Crystal,
DX bell, Morphing drone + default)
- a-app.js: Modular mode registered, paramMeta:change -> resizeMLP,
modular DSP state persisted under modularDspState, window.__nisps
debug hooks for programmatic control
Tests: tests/e2e/modular-mode.spec.js (11 Playwright tests, all passing
including DSP state survives reload, sub-engine swap keeps paramCount,
preset apply verification).
Also fixes a pre-existing build.sh bug where the -e flag caused faust
to overwrite .wasm outputs with expanded DSP source text, leaving
additive/fm-matrix/eoc-* committed as invalid WebAssembly. Rebuilt all
affected engines with the corrected script. Added an early-message
buffer to faust-worklet-processor.js so setParam calls arriving before
wasm instantiation are queued rather than dropped (needed when the user
configures modular state before clicking Start Audio).
