GLTF File

Files with the GLTF extension store information about three-dimensional - 3D GL models, but in the form of JSON data. This makes their size and the power needed to process them in applications using GL libraries significantly smaller. The format, also known as JPEG 3D, was developed as part of a collaboration in the Khronos Group 3D Formats Working Group.

Specification for the GLTF file format

Resources for the GLTF format are defined as JSON capable of handling external files. A 3D model can be represented using:

• The GLTF scene description, model/gltf+json, which consists of:
  • node hierarchy,
  • materials,
  • cameras,
  • descriptors for meshes, animations, and constructs,
• Binary files BIN, application/octet-stream‎, with buffer data, for example, animations and geometry,
• Textures - image files in JPEG or PNG format, image/jpeg, image/png.

Limitations of the JSON format for GLTF

GLTF files must meet several standards that allow for the simplification of the standard's support implementation. These limit the definition of JSON to files using UTF-8 encoding without BOM, and defined strings should be written using ASCII. Additionally, names within objects cannot be duplicated. Thanks to GLTF, one can obtain files of small sizes that allow for quick loading, full representation of the three-dimensional scene, and its expandability.