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Python library for reading, writing and managing 3D objects in the Khronos Group gltf and gltf2 formats.

Project description


This is a library for reading, writing and handling GLTF files. It works for Python3.6 and above.

It supports the entire specification, including materials and animations. Main features are:

  • GLB and GLTF support
  • Buffer data conversion
  • Extensions
  • All attributes are type-hinted


pip install pygltflib

How do I...

Create an empty GLTF2 object?

from pygltflib import GLTF2

gltf = GLTF2()

Add a scene?

from pygltflib import GLTF2, Scene

gltf = GLTF2()
scene = Scene()
gltf.scenes.append(scene)  # scene available at gltf.scenes[0]

Load a file?

filename = "glTF-Sample-Models/2.0/AnimatedCube/glTF/AnimatedCube.gltf"
gltf = GLTF2().load(filename)

Load a binary glb file?

glb_filename = "glTF-Sample-Models/2.0/Box/glTF-Binary/Box.glb"
glb = GLTF2().load(glb_filename)  # load method auto detects based on extension

Load a binary file with an unusual extension?

glb = GLTF2().load_binary("BinaryGLTF.glk")   # load_json and load_binary helper methods

Convert buffers to glb binary buffers?

from pygltflib import GLTF2, BufferFormat

gltf = GLTF2().load("glTF-Sample-Models/2.0/Box/glTF/Box.gltf")
gltf.convert_buffers(BufferFormat.BINARYBLOB)   # convert buffers to GLB blob

Convert buffer to data uri (embedded) buffer?

gltf.convert_buffers(BufferFormat.DATAURI)  # convert buffer URIs to data.

Convert buffers to binary file (external) buffers?

gltf.convert_buffers(BufferFormat.BINFILE)   # convert buffers to files"test.gltf")  # all the buffers are saved in 0.bin, 1.bin, 2.bin.

Convert a glb to a gltf file?

from pygltflib.utils import glb2gltf, gltf2glb

# convert glb to gltf

Access an extension?

# on a primitve

# on a material

Add a custom attribute to Attributes?

# Application-specific semantics must start with an underscore, e.g., _TEMPERATURE.
a = Attributes()

gltf.meshes[0].primitives[0].attributes._MYOTHERATTRIBUTE = 456


This is an unofficial library that tracks the official file format for GLTF2.

The library was initially built to load and save simple meshes but support for the entire spec, including materials and animations is pretty good. Supports both json (.gltf) and binary (.glb) file formats, although .glb support is missing some features at the moment.

It requires python 3.6 and above because it uses dataclasses and all attributes are type hinted. And f-strings, plenty of f-strings.

Check the table below for an idea of which sample models validate.

Questions? Contributions? Bug reports? Open an issue on the gitlab page for the project. We are very interested in hearing your use cases for pygltflib to help drive the roadmap.


  • Add helper functions for creating meshes
  • Test coverage
  • Enforce single underscore on custom Attribute attributes
  • Automated validation and visual inspection


  • Luke Miller
  • Sebastian Höffner
  • Arthur van Hoff
  • Arifullah Jan
  • Daniel Haehn


pygltflib made for 'The Beat: A Glam Noir Game' supported by Film Victoria.


  • 1.11.6

    • add support for extensions
    • add support for extras
    • add support for custom attributes on Attributes
    • set Primitive.attributes to None by default (use primitive.attributes = Attributes())
    • remove warning about byteStride as that is not the responsibility of this library
    • add lots of tests
  • 1.11.5

    • reorder identify_uri to avoid using lengthy byte strings as file names
    • assign parent path when saving so bin files save to same path
  • 1.11.4

    • remove padding
    • improve dataclasses-json backwards compatibility
  • 1.11.3

    • fix import issue with
  • 1.11.2

    • fix issue with long data uris saving in glb
    • fix compatibility issue with different versions of dataclasses-json
  • 1.11.1

    • update documentation
    • improve packaging
  • 1.11

    • add access to internal glb binary data via GLTF.binary_blob()
    • add convert_buffers method to switch buffer formats between data uri, binary files and binary blobs
  • 1.10

    • handle empty buffers on save
    • warn about unsupported data uri bufferViews
    • allow transparent textures (with alpha channel)
  • 1.9

    • use factories to create Attributes and Asset objects
  • 1.8

    • allow images to point to bufferViews
  • 1.7

    • preserve order of bufferViews when saving to glb
    • pad binary chunks within embedded data correctly
  • 1.6

    • provide better support for binary (.glb) files (bug fixes)
    • promote load_json, load_binary, save_json and save_binary from internal methods
  • 1.5

    • align embedded data correctly
    • add glb2gltf and gltf2glb util functions to pygltflib.utils for easy file conversion
  • 1.4

    • add basic support for saving to binary GLTF (.glb) files
    • move undocumented non-core methods to pygltfib.utils
  • 1.3

    • add basic support for reading binary GLTF (.glb) files
  • 1.2

    • provide better json support
    • remove numpy requirement
    • suppress infer warning
    • add basic default methods
  • 1.0

    • initial release


pip install pygltflib


git clone

More Detailed Usage

Note: These examples use the official sample models provided by Khronos at:

A simple mesh
from pygltflib import *

# create gltf objects for a scene with a primitive triangle with indexed geometry
gltf = GLTF2()
scene = Scene()
mesh = Mesh()
primitive = Primitive()
node = Node()
buffer = Buffer()
bufferView1 = BufferView()
bufferView2 = BufferView()
accessor1 = Accessor()
accessor2 = Accessor()

# add data
buffer.byteLength = 44

bufferView1.buffer = 0
bufferView1.byteOffset = 0
bufferView1.byteLength = 6 = ELEMENT_ARRAY_BUFFER

bufferView2.buffer = 0
bufferView2.byteOffset = 8
bufferView2.byteLength = 36 = ARRAY_BUFFER

accessor1.bufferView = 0
accessor1.byteOffset = 0
accessor1.componentType = UNSIGNED_SHORT
accessor1.count = 3
accessor1.type = SCALAR
accessor1.max = [2]
accessor1.min = [0]

accessor2.bufferView = 1
accessor2.byteOffset = 0
accessor2.componentType = FLOAT
accessor2.count = 3
accessor2.type = VEC3
accessor2.max = [1.0, 1.0, 0.0]
accessor2.min = [0.0, 0.0, 0.0]

primitive.attributes.POSITION = 1
node.mesh = 0
scene.nodes = [0]

# assemble into a gltf structure

# save to file"triangle.gltf")

Loading and saving

pygltflib can load json-based .GLTF files and binary .GLB files, based on the file extension.

GLTF files

>>> from pygltflib import GLTF2
>>> filename = "glTF-Sample-Models/2.0/AnimatedCube/glTF/AnimatedCube.gltf"
>>> gltf = GLTF2().load(filename)
>>> gltf.scene

>>> gltf.scenes
[Scene(name='', nodes=[0])]

>>> gltf.nodes[0]
Node(mesh=0, skin=None, rotation=[0.0, -1.0, 0.0, 0.0], translation=[], scale=[], children=[], matrix=[], camera=None, name='AnimatedCube')
>>> gltf.nodes[0].name

>>> gltf.meshes[0].primitives[0].attributes

>>> filename2 = "test.gltf"

GLB files

>>> from pygltflib import GLTF2
>>> glb_filename = "glTF-Sample-Models/2.0/Box/glTF-Binary/Box.glb"
>>> glb = GLTF2().load(glb_filename)
>>> glb.scene

>>> glb.scenes
[Scene(name='', nodes=[0])]

>>> glb.nodes[0]
Node(mesh=None, skin=None, rotation=[], translation=[], scale=[], children=[1], matrix=[1.0, 0.0, 0.0, 0.0, 0.0, 0.0, -1.0, 0.0, 0.0, 1.0, 0.0, 0.0, 0.0, 0.0, 0.0, 1.0], camera=None, name=None)

>>> glb.meshes[0].primitives[0].attributes
Attributes(POSITION=2, NORMAL=1, TANGENT=None, TEXCOORD_0=None, TEXCOORD_1=None, COLOR_0=None, JOINTS_0=None, WEIGHTS_0=None)


>>> glb.binary_blob()  # read the binary blob used by the buffer in a glb
<a bunch of binary data>

Converting files

First method
>>> from pygltflib import GLTF2

>>> # convert glb to gltf
>>> glb = GLTF2().load("glTF-Sample-Models/2.0/Box/glTF-Binary/Box.glb")

>>> # convert gltf to glb
>>> gltf = GLTF2().load("glTF-Sample-Models/2.0/Box/glTF/Box.gltf")
Second method using utils
>>> from pygltflib import GLTF2
>>> from pygltflib.utils import glb2gltf, gltf2glb

>>> # convert glb to gltf
>>> glb2gltf("glTF-Sample-Models/2.0/Box/glTF-Binary/Box.glb")

>>> # convert gltf to glb
>>> gltf2glb("glTF-Sample-Models/2.0/Box/glTF/Box.gltf", "test.glb", override=True)

Converting buffers

The data for a buffer in a GLTF2 files can be stored in the buffer object's URI string or in a binary file pointed to by the buffer objects' URI string or as a binary blob inside a GLB file.

While saving and loading GLTF2 files is mostly handled transparently by the library, there may be some situations where you want a specific type of buffer storage.

For example, if you have a GLTF file that stores all the associated data in .bin files but you want to create a single file, you need to convert the buffers from binary files to data uris or glb binary data.

There is a convenience method named conver_buffers that can help.

>>> from pygltflib import GLTF2, BufferFormat

>>> gltf = GLTF2().load("glTF-Sample-Models/2.0/Box/glTF/Box.gltf")
>>> gltf.convert_buffers(BufferFormat.DATAURI)  # convert buffer URIs to data.
>>> gltf.save_binary("test.glb")  # try and save, will get warning.
Warning: Unable to save data uri to glb format.

>>> gltf.convert_buffers(BufferFormat.BINARYBLOB)   # convert buffers to GLB blob
>>> gltf.save_binary("test.glb")

>>> gltf.convert_buffers(BufferFormat.BINFILE)   # convert buffers to files
>>>"test.gltf")  # all the buffers are saved in 0.bin, 1.bin, 2.bin.


The GLTF2 spec allows for extensions to added to any component of a GLTF file.

As of writing (August 2019) there are about a dozen extensions from Khronos and other vendors

In pygltflib, extensions are loaded as ordinary dict objects and so should be accessed like regular key,value pairs.

For example extensions["KHR_draco_mesh_compression"]["bufferView"] instead of extensions["KHR_draco_mesh_compression"].bufferView.

This allows future extensions to be automatically supported by pygltflib.

Running the tests

Status of gltf-validator

Using sample models loaded and then saved using this library, here are validator reports (blank is untested). If available, The result of a visual inspection is in brackets next to the validator result.

Validator Status

Model gltf to gltf gltf to glb glb to gltf glb to glb
2CylinderEngine passes passes passes passes
AlphaBlendModeTest passes passes passes passes
AnimatedCube passes passes no glb available no glb available
AnimatedMorphCube passes passes passes passes
AnimatedMorphSphere passes passes passes passes
AnimatedTriangle passes passes no glb available no glb available
Avocado passes passes passes passes
BarramundiFish passes passes passes passes
BoomBox passes passes passes passes
BoomBoxWithAxes passes passes no glb available no glb available
Box passes passes passes passes
BoxAnimated passes passes passes
BoxInterleaved passes passes passes
BoxTextured passes passes
BoxTexturedNonPowerOfTwo passes passes
BoxVertexColors passes passes
BrainStem passes passes passes
Buggy passes passes passes
Cameras passes passes no glb available no glb available
CesiumMan passes passes
CesiumMilkTruck passes passes
Corset passes passes passes passes
Cube passes passes no glb available no glb available
DamagedHelmet passes passes passes passes
Duck passes passes passes passes
FlightHelmet passes passes no glb available no glb available
GearboxAssy passes passes
Lantern passes passes
MetalRoughSpheres passes passes
Monster passes passes
MultiUVTest passes passes
NormalTangentMirrorTest passes passes
NormalTangentTest passes passes passes
OrientationTest passes passes
ReciprocatingSaw passes passes
RiggedFigure passes passes
RiggedSimple passes passes
SciFiHelmet passes passes no glb available no glb available
SimpleMeshes passes passes no glb available no glb available
SimpleMorph passes passes no glb available no glb available
SimpleSparseAccessor passes passes no glb available no glb available
SpecGlossVsMetalRough passes passes passes passes
Sponza passes passes no glb available no glb available
Suzanne passes passes no glb available no glb available
TextureCoordinateTest passes passes passes passes
TextureSettingsTest passes passes passes passes
TextureTransformTest passes passes no glb available no glb available
Triangle passes passes no glb available no glb available
TriangleWithoutIndices passes passes no glb available no glb available
TwoSidedPlane passes passes no glb available no glb available
VC passes fails passes passes
VertexColorTest passes passes passes passes
WaterBottle passes passes passes passes



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