glTF

glTF is built around a JSON-based scene description that references external buffers for binary data such as vertex positions, normals, and animation keyframes. This separation allows for efficient streaming and incremental loading. The format supports a full scene graph with nodes, meshes, cameras, and lights, and includes a physically based rendering (PBR) material model using metallic-roughness or specular-glossiness workflows. Animations are defined via keyframe tracks that can target node transforms, weights for morph targets, or skinning data for skeletal animation. The binary container format, .glb, packages the JSON and all buffers into a single file, reducing HTTP requests and simplifying distribution.¹

glTF has become the standard interchange format for 3D content across industries, supported by major engines like Unity, Unreal, and Godot, as well as by web libraries such as Three.js and Babylon.js. It is used in product configurators, architectural visualization, and augmented reality applications. The format is also the basis for the 3D Tiles specification for massive geospatial datasets. The Khronos Group maintains a validator and a set of official extensions, including KHR_draco_mesh_compression for geometry compression and KHR_materials_variants for multi-material objects.²

Beyond the core features, glTF includes several niche capabilities. It supports the KHR_texture_transform extension for UV scrolling and mirroring, and KHR_materials_clearcoat for simulating painted surfaces. The format also allows for sparse accessors, which efficiently store only modified elements of large arrays, useful for morph targets. glTF 2.0 dropped the original 1.0's reliance on external shaders, instead using a fixed-function pipeline that is easier to validate. The community has developed tools like glTF-Transform for programmatic manipulation, and the format has been adopted by the Smithsonian Institution for 3D digitization of artifacts.³

The Khronos Group continues to evolve glTF with extensions for advanced features such as ray tracing (KHR_materials_raytracing) and interactive experiences (KHR_animation_pointer). The glTF 2.0 specification is stable, but the extension ecosystem allows for rapid innovation without breaking core compatibility. There is ongoing work to improve compression, including the adoption of meshopt compression and the integration of the Draco library. As the metaverse and digital twin initiatives grow, glTF is positioned to be a foundational format for interoperable 3D content.⁴

PBR

Physically Based Rendering – a shading model that simulates light interaction with surfaces based on physical properties.

GLB

Binary container format for glTF that embeds all resources in a single file.

Morph target

A deformation of a mesh's vertices, used for facial animation or shape blending.