memlnaut-nisps/playground/faust/build.sh

#!/usr/bin/env bash
# build.sh — compile all Faust DSP files in this directory to WASM + JSON
#
# Required tools:
#   faust >= 2.60.0   (https://faust.grame.fr / nix: faust)
#   emcc  >= 3.1.x    (Emscripten, already present at /usr/lib/emscripten/emcc)
#
# Usage:
#   cd playground/faust && ./build.sh
#
# Outputs (alongside each .dsp):
#   <name>.wasm   — compiled audio DSP binary
#   <name>.json   — Faust UI descriptor (consumed by faustJsonToParamMeta)
#   <name>.js     — JS glue / AudioWorklet wrapper generated by faust2wasm
#
# The JSON descriptor is the key artifact: it contains the full UI tree
# (hslider / vslider / nentry / groups) that faustJsonToParamMeta.js parses
# into the playground's standard paramMeta format.

set -euo pipefail

SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"

# ---------------------------------------------------------------------------
# Dependency checks
# ---------------------------------------------------------------------------
#
# If faust isn't in PATH, automatically re-exec under `nix-shell -p faust`
# when nix-shell is available. NISPS_BUILD_IN_NIX_SHELL prevents infinite
# recursion if the nix-shell environment somehow still lacks faust.

if ! command -v faust &>/dev/null; then
  if [ "${NISPS_BUILD_IN_NIX_SHELL:-0}" = "1" ]; then
    echo "ERROR: 'faust' still not found inside nix-shell. Check your nixpkgs channel."
    exit 1
  fi
  if command -v nix-shell &>/dev/null; then
    echo "faust not in PATH — re-exec under nix-shell -p faust ..."
    exec env NISPS_BUILD_IN_NIX_SHELL=1 nix-shell -p faust --run "\"$0\" $*"
  fi
  echo ""
  echo "ERROR: 'faust' not found in PATH (and nix-shell is unavailable)."
  echo ""
  echo "Install options:"
  echo "  nix-shell -p faust             # one-off"
  echo "  nix profile install nixpkgs#faust  # permanent"
  echo "  Or download from: https://faust.grame.fr/downloads/"
  echo ""
  echo "Required version: >= 2.60.0"
  echo "Check: faust --version"
  exit 1
fi

FAUST_VER="$(faust --version 2>&1 | head -1)"
echo "faust: $FAUST_VER"

# emcc is optional — faust -lang wasm doesn't require it.
# It is needed if you want to link extra C++ into the WASM module.
if command -v emcc &>/dev/null; then
  EMCC_VER="$(emcc --version 2>&1 | head -1)"
  echo "emcc : $EMCC_VER"
else
  echo "emcc : not found (not required for basic faust -lang wasm builds)"
fi

echo ""

# ---------------------------------------------------------------------------
# Compile each .dsp
# ---------------------------------------------------------------------------

DSP_FILES=("$SCRIPT_DIR"/*.dsp)

if [ ${#DSP_FILES[@]} -eq 0 ]; then
  echo "No .dsp files found in $SCRIPT_DIR"
  exit 0
fi

for DSP in "${DSP_FILES[@]}"; do
  NAME="$(basename "$DSP" .dsp)"
  echo "Compiling $NAME.dsp ..."

  # Faust -o is interpreted relative to -O (so we must cd into SCRIPT_DIR
  # and pass just the filename). Class names (-cn) must be valid C identifiers,
  # so dash characters are replaced with underscores.
  CLASSNAME="$(echo "$NAME" | tr '-' '_')"

  # Step 1: emit WASM binary + JS glue
  # -lang wasm      — target WebAssembly
  # -cn <Name>      — class name prefix in generated JS
  # -O <dir>        — output directory
  #
  # NB: do NOT pass -e here. In Faust 2.79, -e means "export expanded DSP
  # (textual)" — it causes the .wasm output to be Faust source text, not a
  # real WebAssembly binary. This script historically used -e by mistake.
  ( cd "$SCRIPT_DIR" && \
    faust -lang wasm \
          -cn "$CLASSNAME" \
          -O "$SCRIPT_DIR" \
          "${NAME}.dsp" \
          -o "${NAME}.wasm" )

  # Note: `faust -lang wasm -O . foo.dsp -o foo.wasm` already writes
  # foo.json alongside foo.wasm with the wasm-native descriptor (including
  # numeric `index` fields that workers use as setParamValue zone addresses).
  # The old standalone `-json` pass produced a smaller JSON WITHOUT the
  # `index` field, which is the wrong shape for workers — don't run it.
  if [ ! -f "$SCRIPT_DIR/${NAME}.json" ]; then
    echo "  WARNING: ${NAME}.json not produced — check faust version"
  fi

  if [ -f "$SCRIPT_DIR/${NAME}.wasm" ]; then
    WASM_SIZE="$(du -h "$SCRIPT_DIR/${NAME}.wasm" | cut -f1)"
    echo "  -> ${NAME}.wasm (${WASM_SIZE})"
  fi
  if [ -f "$SCRIPT_DIR/${NAME}.json" ]; then
    echo "  -> ${NAME}.json"
  fi
done

echo ""
echo "Done. Load engines in the playground via FaustEngineBase:"
echo "  import { AdditiveEngine } from './js/synth/additive-engine.js';"