pygltflib

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

Quickstart

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

Access the first node (the objects comprising the scene) of a scene?

gltf = GLTF2().load("glTF-Sample-Models/2.0/Box/glTF/Box.gltf")
current_scene = gltf.scenes[gltf.scene]
node_index = current_scene.nodes[0]  # scene.nodes is the indices, not the objects 
box = gltf.nodes[nodex_index]
box.matrix  # will output vertices for the box object

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
gltf.save("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
glb2gltf("glTF-Sample-Models/2.0/Box/glTF-Binary/Box.glb")

Access an extension?

# on a primitve
gltf.meshes[0].primitives[0].extensions['KHR_draco_mesh_compression']

# on a material
gltf.materials[0].extensions['ADOBE_materials_thin_transparency']

Add a custom attribute to Attributes?

# Application-specific semantics must start with an underscore, e.g., _TEMPERATURE.
a = Attributes()
a._MYCUSTOMATTRIBUTE = 123

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

Remove a bufferView?

gltf.remove_bufferView(0)  # this will update all accessors, images and sparse accessors to remove the first bufferView

Validate a gltf object?

from pygltflib import GLTF2
from pygltflib.validator import validate, summary
filename = "glTF-Sample-Models/2.0/AnimatedCube/glTF/AnimatedCube.gltf"
gltf = GLTF2().load(filename)
validate(gltf)  # will throw an error depending on the problem
summary(gltf)  # will pretty print human readable summary of errors
# NOTE: Currently this experimental validator only validates a few rules about GLTF2 objects

Export texture images from a GLTF file to their own PNG files

from pygltflib import GLTF2
from pygltflib.utils import ImageFormat
filename = "glTF-Sample-Models/2.0/AnimatedCube/glTF/AnimatedCube.gltf"
gltf = GLTF2().load(filename)
gltf.convert_images(ImageFormat.FILE)
gltf.images[0].uri  # will now be 0.png and the texture image will be saved in 0.png

Export texture images from a GLTF file to their own PNG files using custom file names

from pygltflib import GLTF2
from pygltflib.utils import ImageFormat
filename = "glTF-Sample-Models/2.0/AnimatedCube/glTF/AnimatedCube.gltf"
gltf = GLTF2().load(filename)
gltf.images[0].name = "cube.png"  # will save the data uri to this file (regardless of data format)
gltf.convert_images(ImageFormat.FILE)
gltf.images[0].uri  # will now be cube.png and the texture image will be saved in cube.png

Import PNG files as textures into a GLTF.

from pygltflib import GLTF2
from pygltflib.utils import ImageFormat, Image
gltf = GLTF2()
image = Image()
image.uri = "myfile.png"
gltf.images.append(image)
gltf.convert_images(ImageFormat.DATAURI)
gltf.images[0].uri  # will now be something like "data:image/png;base64,iVBORw0KGg..."
gltf.images[0].name  # will be myfile.png

About

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.

Roadmap

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

Contributors

• Luke Miller
• Sebastian Höffner
• Arthur van Hoff
• Arifullah Jan
• Daniel Haehn
• Jon Time
• Laurie O
• Peter Suter
• Frédéric Devernay
• Julian Stirling

Thanks

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

Changelog

• 1.13.5

  • fix Matrix, Translation, Scale, and Rotation to default to None
  • change utils.validator by moving to validator.validate
  • add validator.summary to provide human readable output of validator
  • add some more unit tests

• 1.13.4

  • add warning to remove_bufferView if leaving dangling references to removed bufferView
  • add tests for remove_bufferView
  • add node access and remove_bufferView examples to README
  • add validation for animation channels
  • change metallicRoughnessTexture to use TextureInfo
  • change requirements to not install dataclasses in python 3.7 and above
  • fix remove_bufferView when sparse accessor is None
  • fix spelling of InvalidAccessorSparseIndicesComponentTypeException

• 1.13.3

  • add support to GLTF.convert_images to convert from buffers to image files. NOTE: Does not update buffer yet.
  • add support to GLTF.convert_images to convert from buffers to data uris. NOTE: Does not update buffer yet.
  • add accessor sparse indices bufferview check to validator
  • fix test suite to write tmp files to tmp directory instead of install directory
  • remove support for old versions of dataclasses-json
  • renamed CUBICSPLINE, LINEAR and STEP to ANIM_LINEAR, ANIM_STEP, ANIM_CUBICSPLINE to fix clash with webGL constants
  • change bin file conversion to only lose binary blob on successful file export

• 1.13.2

  • add deprecated to pip setup

• 1.13.1

  • add GLTF.convert_images method for converting texture image data from data uris to files and vice versa
  • add 'name' attribute to Image
  • add more unittests
  • change Primitive so that Attributes is created on init

• 1.13.0

  • NOTE: There are a few small deprecations in this version to tighten up the library that will be removed in version 2.0.0
  • deprecate class SparseAccessor in favour of AccessorSparseIndices and AccessorSparseValues (please update your code)
  • deprecate class MaterialTexture in favour of TextureInfo to better match GLTF2 specification (please update your code)
  • deprecate AlphaMode ENUM in favour of constants (eg replace AlphaMode.OPAQUE with OPAQUE (please update your code)
  • fix support for material.occlusionTextureInfo
  • fix support for material.normalTextureInfo
  • fix sampler support in Animation class by adding AnimationSampler
  • add default values for Accessor, AnimationSampler, BufferView, Material, PbrMetallicRoughness, Primitive, Sampler
  • add Optional to attributes for better type hinting
  • add initial utils.validator to validate GLTF2 object accessor and bufferViews

• 1.12.0

  • fix bug with binfile path handling

• 1.11.10

  • convert load methods from staticmethod to classmethods

• 1.11.9

  • change GLTF.load to a staticmethod
  • add AlphaMode enum type

• 1.11.8

  • add missing top level extensions

• 1.11.7

  • add missing normalized flag to Accessor

• 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 setup.py

• 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

Install

pip install pygltflib

Source

git clone https://gitlab.com/dodgyville/pygltflib

More Detailed Usage

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

https://github.com/KhronosGroup/glTF-Sample-Models

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.uri = "data:application/octet-stream;base64,AAABAAIAAAAAAAAAAAAAAAAAAAAAAIA/AAAAAAAAAAAAAAAAAACAPwAAAAA="
buffer.byteLength = 44

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

bufferView2.buffer = 0
bufferView2.byteOffset = 8
bufferView2.byteLength = 36
bufferView2.target = 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
gltf.scenes.append(scene)
gltf.meshes.append(mesh)
gltf.meshes[0].primitives.append(primitive)
gltf.nodes.append(node)
gltf.buffers.append(buffer)
gltf.bufferViews.append(bufferView1)
gltf.bufferViews.append(bufferView2)
gltf.accessors.append(accessor1)
gltf.accessors.append(accessor2)

# save to file
gltf.save("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
0

>>> 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
'AnimatedCube'

>>> gltf.meshes[0].primitives[0].attributes
Attributes(NORMAL=4, POSITION=None, TANGENT=5, TEXCOORD_0=6)

>>> filename2 = "test.gltf"
>>> gltf.save(filename2)

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
0

>>> 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.save("test.glb")

>>> 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")
>>> glb.save("test.gltf")

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

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 convert_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
>>> gltf.save("test.gltf")  # all the buffers are saved in 0.bin, 1.bin, 2.bin.

Converting texture images

The image data for textures in GLTF2 files can be stored in the image objects URI string or in an image file pointed to by the image objects' URI string or as part of the buffer.

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 image storage.

For example, if you have a GLB file that stores all its image files in .PNG files but you want to create a single GLTF file, you need to convert the images from files to data uris.

Currently converting images to and from the buffer is not supported. Only image files and data uris are supported.

There is a convenience method named convert_images that can help.

>>> # embed an image file to your GLTF.

>>> from pygltflib.utils import ImageFormat, Image
>>> gltf = GLTF2()
>>> image = Image()
>>> image.uri = "myfile.png"
>>> gltf.images.append(image)

>>> gltf.convert_images(ImageFormat.DATAURI)  # image file will be imported into the GLTF
>>> gltf.images[0].uri  # will now be something like "data:image/png;base64,iVBORw0KGg..."
>>> gltf.images[0].name  # will be myfile.png


>>> # create an image file from GLTF data uris

>>> from pathlib import Path
>>> from pygltflib.utils import ImageFormat, Image
>>> gltf = GLTF2()
>>> image = Image()
>>> image.uri = "data:image/png;base64,iVBORw0KGg..."
>>> image.name = "myfile.png"  # optional file name, if not provided, the image files will be called "0.png", "1.png"
>>> gltf.images.append(image)

>>> gltf.convert_images(ImageFormat.FILE)  # image file will be imported into the GLTF
>>> gltf.images[0].uri  # will be myfile.png
"myfile.png"

>>> Path("myfile.png").exists()
True

Extensions

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.

Extras should work the same way.

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

utils.validator status

What does pygltflib.utils.validator test? NOTE: At the moment the validator raises an exception when an rule is broken. If you have ideas of the best way to return information on validation warnings/errors please open a ticket on our gitlab.

Rule	validator tests	exception raised
accessor.componentType must be valid	yes	InvalidAcccessorComponentTypeException
accessor min and max arrays must be valid length	yes	InvalidArrayLengthException
accessor min and max arrays must be same length	yes	MismatchedArrayLengthException
mesh.primitive.mode must be valid	yes	InvalidMeshPrimitiveMode
accessor.sparse.indices.componentType must be valid	yes	InvalidAccessorSparseIndicesComponentTypeException
bufferView byteOffset and byteStrides must be valid	yes	InvalidValueError
bufferView targets must be valid	yes	InvalidBufferViewTarget
all other tests	no

unittests

git clone https://github.com/KhronosGroup/glTF-Sample-Models
pytest test_pygltflib.py