📄 threejs/Addons/Loaders/STLLoader

File: STLLoader.md | Updated: 11/15/2025


title: STLLoader category: Addons layout: docs

STLLoader

A loader for the STL format, as created by Solidworks and other CAD programs.

Supports both binary and ASCII encoded files. The loader returns a non-indexed buffer geometry.

Limitations:

  • Binary decoding supports "Magics" color format (http://en.wikipedia.org/wiki/STL_(file_format)#Color_in_binary_STL).
  • There is perhaps some question as to how valid it is to always assume little-endian-ness.
  • ASCII decoding assumes file is UTF-8.

For binary STLs geometry might contain colors for vertices. To use it:

// use the same code to load STL as above
if ( geometry.hasColors ) {
	material = new THREE.MeshPhongMaterial( { opacity: geometry.alpha, vertexColors: true } );
}
const mesh = new THREE.Mesh( geometry, material );

For ASCII STLs containing multiple solids, each solid is assigned to a different group. Groups can be used to assign a different color by defining an array of materials with the same length of geometry.groups and passing it to the Mesh constructor:

const materials = [];
const nGeometryGroups = geometry.groups.length;
for ( let i = 0; i < nGeometryGroups; i ++ ) {
	const material = new THREE.MeshPhongMaterial( { color: colorMap[ i ], wireframe: false } );
	materials.push( material );
}
const mesh = new THREE.Mesh(geometry, materials);

Code Example

const loader = new STLLoader();
const geometry = await loader.loadAsync( './models/stl/slotted_disk.stl' )
scene.add( new THREE.Mesh( geometry ) );

Import

STLLoader is an addon, and must be imported explicitly, see Installation#Addons.

import { STLLoader } from 'three/addons/loaders/STLLoader.js';

Constructor

new STLLoader( manager : LoadingManager )

Constructs a new STL loader.

manager | The loading manager.
---|---

Methods

.load( url : string, onLoad : function, onProgress : onProgressCallback, onError : onErrorCallback )

Starts loading from the given URL and passes the loaded STL asset to the onLoad() callback.

url | The path/URL of the file to be loaded. This can also be a data URI.
---|---
onLoad | Executed when the loading process has been finished.
onProgress | Executed while the loading is in progress.
onError | Executed when errors occur.

Overrides: Loader#load

.parse( data : ArrayBuffer ) : BufferGeometry

Parses the given STL data and returns the resulting geometry.

data | The raw STL data as an array buffer.
---|---

Overrides: Loader#parse

Returns: The parsed geometry.

Source

examples/jsm/loaders/STLLoader.js