@lofcz/openscad-wasm

OpenSCAD compiled to WebAssembly — render .scad to STL/3MF/OFF/… in the browser or Node, no native binary required.

Built from lofcz/openscad-wasm, which tracks openscad/openscad-wasm plus:

• the freetype no-hinting patch — stock builds trap the whole WASM module (RuntimeError: null function or function signature mismatch) on any font without a TrueType bytecode program, i.e. most modern fonts;
• mirrored GMP/MPFR downloads with pinned checksums for reliable CI builds;
• runtime extensions: bundled Liberation fonts (text()) and the MCAD library.

Install

npm install @lofcz/openscad-wasm

Browser usage

import createOpenSCAD from "@lofcz/openscad-wasm";
import { addFonts } from "@lofcz/openscad-wasm/fonts";

const instance = await createOpenSCAD({ noInitialRun: true });
addFonts(instance); // optional: enables text() with bundled Liberation fonts

instance.FS.writeFile("/input.scad", "cube(10);");
const exit = instance.callMain([
  "/input.scad",
  "--backend", "Manifold",
  "--export-format", "binstl",
  "-o", "/out.stl",
]);
if (exit !== 0) throw new Error(`openscad exited with ${exit}`);

const stl = instance.FS.readFile("/out.stl"); // Uint8Array

Bundlers: make sure openscad.wasm is served as a static asset. The wrapper resolves it with new URL("openscad.wasm", import.meta.url); Vite and webpack 5 handle that pattern natively.

Node usage

Node's fetch cannot load file:// URLs, so hand the module the binary directly:

import { readFileSync } from "node:fs";
import { createRequire } from "node:module";
import createOpenSCAD from "@lofcz/openscad-wasm";

const require = createRequire(import.meta.url);
const wasmBytes = readFileSync(require.resolve("@lofcz/openscad-wasm/openscad.wasm"));

const instance = await createOpenSCAD({
  noInitialRun: true,
  instantiateWasm(imports, done) {
    WebAssembly.instantiate(wasmBytes, imports).then((r) => done(r.instance));
    return {};
  },
});

API

See openscad.d.ts. The surface is the emscripten module: callMain(args) runs openscad <args>, FS is the in-memory filesystem the .scad input, MCAD/fonts and exported files live in.

Rebuilding

The WASM binary is built from the repo root with Docker only:

make ENV=release   # or: ./build.sh
make npm           # assemble this package from build/ artifacts

License

GPL-2.0 — see COPYING. OpenSCAD and its dependencies (CGAL, FreeType, HarfBuzz, …) are compiled into the binary.