@amandaghassaei/stl-parser NPM

@amandaghassaei/stl-parser

Standalone module for loading and parsing binary/ASCII STL files – unit tested and written in TypeScript. Parsing code based on Threejs STLLoader.

Live demo: apps.amandaghassaei.com/stl-parser/demo/

STL File Format

The .stl file format stores geometry (and sometimes color) information for 3D triangulated meshes. stl-parser does not generate or render .stl files, but it will allow you to parse them in a browser or Nodejs environment. Example .stl files can be found in test/stl/.

Installation

Install via npm

npm install @amandaghassaei/stl-parser

and import into your project:

import {
  parseSTL,
  loadSTL,
  loadSTLAsync,
} from '@amandaghassaei/stl-parser';

Import into HTML

Import stl-parser.min.js directly into your html:

<html>
  <head>
    <script src="stl-parser.min.js"></script>
  </head>
  <body>
  </body>
</html>

STLParserLib will be accessible globally:

const { parseSTL, loadSTL, loadSTLAsync } = STLParserLib;

Use

Full API documentation in docs.

// Load and parse the .stl file using url or File object.
loadSTL('./teapot.stl', (mesh) => {
  const {
    vertices,
    facesNormals,
    facesColors,
    edgesIndices,
    boundingBox,
  } = mesh;
});
// Also try:
// const mesh = await loadSTLAsync('./teapot.stl');

// Or parse file buffer or string synchronously.
const meshFromBuffer = parseSTL(fs.readFileSync('./teapot.stl'));
const meshFromString = parseSTL(`solid ASCII
  facet normal 0.000000e+00 0.000000e+00 -1.000000e+00
    outer loop
      vertex   1.000000e+01 0.000000e+00 -1.000000e+01
      vertex   0.000000e+00 0.000000e+00 -1.000000e+01
      vertex   1.000000e+01 1.000000e+01 -1.000000e+01
    endloop
  endfacet
  ....
  facet normal 0.000000e+00 -1.000000e+00 0.000000e+00
    outer loop
      vertex   0.000000e+00 0.000000e+00 0.000000e+00
      vertex   1.000000e+01 0.000000e+00 -1.000000e+01
      vertex   1.000000e+01 0.000000e+00 0.000000e+00
    endloop
  endfacet
endsolid`);

vertices is a Float32Array of length 3 * numVertices containing a flat list of vertex positions in the following order [x0, y0, z0, x1, y1, z1, ...]. Each group of three vertices make up a triangle in the .stl mesh – by default, vertices are not shared between triangles in the .stl format, see mergeVertices() below.
facesNormals is a Float32Array of length 3 * numFaces containing a flat list of face normals in the following order [nx0, ny0, nz0, nx1, ny1, nz1, ...]
If available, facesColors is a Float32Array of length 3 * numFaces containing a flat list of face colors in the following order [r0, g0, b0, r1, g1, b1, ...].
edgesIndices is a Uint32Array containing all unique edgesIndices (expressed as pairs of vertex indices) in the mesh in the following order: [e01, e02, e11, e12, ...]. edgesIndices is calculated when queried and then cached.
boundingBox returns the min and max of the mesh's bounding box in the form: { min: [x, y, z], max: [x, y, z] }. boundingBox is calculated when queried and then cached.

The mesh object returned by parseSTL, loadSTL, and loadSTLAsync also exposes methods for modifying its geometry:

mesh.mergeVertices().scaleVerticesToUnitBoundingBox();
const { facesIndices } = mesh;

STLMesh.mergeVertices() merges coincident vertices and adds a facesIndices array to the mesh object. facesIndices has length 3 * numFaces and contains a flat list of triangle face vertex indices in the following order: [v01, v02, v03, v11, v12, v13, ...].
STLMesh.scaleVerticesToUnitBoundingBox() scales the vertices values (in place) to fit inside a unit box centered around the origin.

Build Notes

This library imports fs in Nodejs environments to load files from a url string. This code is never hit in the browser environment (the browser uses a XMLHttpRequest instead), but you may see build warnings due to the import('fs') statement in the code. (I'm wondering if there is a better way to handle this that is compatible for both Nodejs and browser environments, please let me know if you have ideas.)

To fix this warning, you need to set fs as an external dependency in your build settings:

// rollup.config.js
export default {
  ...
  external: ['fs'],
};

// vite.config.js
export default {
  build: {
    rollupOptions: {
      external: ['fs'],
    },
  }
  ...
}

Limitations

See limitations listed in Threejs STLLoader. If you have a file that is not being parsed correctly, please upload it in an Issue so it can be added as a test case. Pull requests welcome.