@draco-rust/stl

Reads and writes binary and ASCII STL in WebAssembly. Which kind a file is follows from its length, not from a leading solid, which binary exporters often write too. It is part of draco-rust and drives the converter.

~48 KiB gzip.

Usage

import init, { read_stl, write_stl } from "@draco-rust/stl";

await init();
const result = read_stl(stlBytes);
if (!result.success) throw new Error(result.error);
const { positions, indices, normals } = result.meshes[0];

const written = write_stl({ positions, indices }, {}); // binary by default
const stl = written.bytes; // Uint8Array; with { format: "ascii" }, also written.text

Meshes keep STL's own shape: three vertices per triangle, each with the facet normal, so a cube reads as 36 vertices rather than 24.

On workers

A large file blocks the calling thread while it is read or written. @draco-rust/stl/pool runs the same functions on workers:

import { createPool } from "@draco-rust/stl/pool";

const pool = createPool({ workers: 2 }); // default: cores - 1, at most 4
const result = await pool.read(bytes); // what read_stl returns
const written = await pool.write(mesh, {}); // what write_stl returns
pool.dispose();

The workers start as work arrives, and the wasm is compiled once for all of them. Inputs are copied to the worker, or handed over with { transfer: true }; { signal } takes an AbortSignal, which rejects the promise at once. A task a worker has started still runs to its end and its result is dropped. With workers: 0, or where there are no workers, the pool runs on the calling thread. It works on Web Workers, Node's worker threads (Node 20.16 and later) and from a CDN, as the decoder's does.

For loading from a CDN or in Node, see the decoder's README; the same init options apply, with @draco-rust/stl/index_bg.wasm as the file.

Licensed under Apache-2.0.

This build

@draco-rust/[email protected] was built from draco-rust commit 4b72cfc8, with draco-core 2.3.2, draco-io 0.6.0, draco-gltf 0.7.0.