glTF 2.1
glTF 2.1 is a focused, backwards-compatible revision of the core spec. It does not break existing glTF 2.0 content. Its goals are:
- Extend the format to support large-scale, complex, and production 3D workflows that are not well served today
- Lay a rigorous foundation — spatial primitives and multi-file composition — that extensions and future spec work can build on reliably
Every feature is being developed using a Design First process: explainers define purpose, scope, behavior, and inter-feature relationships before any schema or normative text is written.
Core Features
The following features are confirmed for inclusion in the glTF 2.1 core. Each has a dedicated explainer linked below.
Complex Scenes
- External Assets - Standardized mechanism for a glTF file to reference external glTF files and assets as part of its scene graph, enabling multi-file scene composition
- Bounding Volume Hierarchy - Per-node bounding volume definitions using implicit shape types
- Shapes - Includes implicit geometric primitives (box, sphere, capsule, cylinder, and others) to core, enabling physics, collision, and procedural workflows without explicit mesh geometry
- Packaging External Assets - Allows a glTF file to act as a virtual package for a complex scene: embedded external assets resolve URIs through the host file's files array, enabling shared buffers, textures, and resources across nested glTF files without modifying original data
- Unified File References - A single array of file references for all future external content types referenced within a glTF file; ships as part of External Assets
- Multiple Scene Deprecation - Formally deprecates the multiple-scenes pattern; glTF files are expected to contain a single scene going forward
Quality of Life improvements
- Promoted Extension Functionality - Promotes the functionality of these specific extensions ratified in glTF 2.0 to required status in glTF 2.1:
EXT_texture_webp
KHR_materials_emissive_strength
KHR_mesh_quantization
KHR_node_visibility
- Thumbnails - Embed standardized preview images directly in a glTF file for use in file browsers, asset managers, and pipelines without requiring a renderer
- 64-Bit Binary File Format - Upgrades GLB chunk length fields from 32-bit to 64-bit, removing the ~4 GB per-chunk size ceiling
- Non-Sequential Attributes - Relaxes the requirement that indexed attribute semantics such as TEXCOORD_* and COLOR_* must start from zero and be consecutive, simplifying conversion workflows
- Accessor Component Type Definitions - Added commonly used type definitions for convenience of extension development
- Unique IDs - String identifiers scoped to a glTF file, providing stable, addressable identity for cross-file referencing and toolchain interoperability
Status and Participation
The specification is under active development. Feature explainers are the current stable reference; schema and normative text to follow.
The glTF 2.1 specification progress will be openly available. Community feedback is encouraged. Organizations seeking a direct role in shaping the spec are welcome to join the Khronos Group and participate in the 3D Formats Working Group glTF 2.1 DTSG.
glTF 2.1
glTF 2.1 is a focused, backwards-compatible revision of the core spec. It does not break existing glTF 2.0 content. Its goals are:
Every feature is being developed using a Design First process: explainers define purpose, scope, behavior, and inter-feature relationships before any schema or normative text is written.
Core Features
The following features are confirmed for inclusion in the glTF 2.1 core. Each has a dedicated explainer linked below.
Complex Scenes
Quality of Life improvements
EXT_texture_webp
KHR_materials_emissive_strength
KHR_mesh_quantization
KHR_node_visibility
Status and Participation
The specification is under active development. Feature explainers are the current stable reference; schema and normative text to follow.
The glTF 2.1 specification progress will be openly available. Community feedback is encouraged. Organizations seeking a direct role in shaping the spec are welcome to join the Khronos Group and participate in the 3D Formats Working Group glTF 2.1 DTSG.