Python STL

stl is a Python library for reading and writing 3D geometry data written in both the binary and ASCII variants of the STL (“STereo Lithography”) format.

STL is commonly used in preparing solid figures for 3D printing and other kinds of automatic manufacturing, and is a popular export format for 3D CAD applications.

(This library has nothing to do with the C++ Standard Template Library.)

Contents:

Reading STL Files

STL files can be read using the functions in the main stl module.

stl.read_ascii_file(file)

Read an STL file in the ASCII format.

Takes a file-like object (supporting a read method) and returns a stl.Solid object representing the data from the file.

If the file is invalid in any way, raises stl.ascii.SyntaxError.

stl.read_binary_file(file)

Read an STL file in the binary format.

Takes a file-like object (supporting a read method) and returns a stl.Solid object representing the data from the file.

If the file is invalid in any way, raises stl.binary.FormatError.

stl.read_ascii_string(data)

Read geometry from a str containing data in the STL ASCII format.

This is just a wrapper around read_ascii_file() that first wraps the provided string in a StringIO.StringIO object.

stl.read_binary_string(data)

Read geometry from a str containing data in the STL binary format.

This is just a wrapper around read_binary_file() that first wraps the provided string in a StringIO.StringIO object.

Writing STL Files

In order to write an STL file you must first construct a valid stl.Solid object containing the data that is to be written.

Files can then be written using stl.Solid.write_ascii() and stl.Solid.write_binary() respectively.

Data Types

The following data types, with stl.Solid as the root, are used to represent data read from or to be written to an STL file.

class stl.Solid(name=None, facets=None)

A solid object; the root element of an STL file.

add_facet(*args, **kwargs)

Append a new facet to the object. Takes the same arguments as the stl.Facet type.

surface_area

The sum of the areas of all facets in the object.

write_ascii(file)

Write this object to a file in STL ascii format.

file must be a file-like object (supporting a write method), to which the data will be written.

write_binary(file)

Write this object to a file in STL binary format.

file must be a file-like object (supporting a write method), to which the data will be written.

class stl.Facet(normal, vertices, attributes=None)

A facet (triangle) from a stl.Solid.

a

The length the side of the facet between vertices[0] and vertices[1]

area

The surface area of the facet, as computed by Heron’s Formula.

b

The length of the side of the facet between vertices[0] and vertices[2]

c

The length of the side of the facet between vertices[1] and vertices[2]

perimeter

The length of the perimeter of the facet.

class stl.Vector3d(x, y, z)

Three-dimensional vector.

Used to represent both normals and vertices of stl.Facet objects.

This is a subtype of tuple, so can also be treated like a three-element tuple in (x, y, z) order.

x

The X value of the vector, which most applications interpret as the left-right axis.

y

The Y value of the vector, which most applications interpret as the in-out axis.

z

The Z value of the vector, which most applications interpret as the up-down axis.

Indices and tables