glTF markers

The GL Transmission Format (.glTF file) is an industry-standard interchange format for the transport of 3D models. Binary GL Transmission Format (.glb) files are binary versions of a glTF file that also include embedded assets such as textures.

Learn more about the glTF specification

glTF markers can contain multiple levels of detail (LODs) to manage their display in an efficient and sensible way across a range of view distances. This scalability means that when the marker is in the distance in a scene, it draws with less complexity than when it is drawn in the foreground, nearer to the viewer.

glTF markers can include material properties such as shininess, roughness, or metalness. This gives models a distinctive sense of realism that can't be achieved with only flat color.

Supported features from the glTF specification

The currently supported features from the glTF specification are as follows:

  • Full-node hierarchies, including node transformations and mesh instancing.
  • The MSFT_lod glTF extension is supported, but only node-based LODs, not material-based LODs. MSFT_lod can only appear in the first node of a scene. If it appears elsewhere, all occurrences of MSFT_lod are ignored.
  • Primitive geometry types: TRIANGLE, TRIANGLE_STRIP, and TRIANGLE_FAN.
  • All vertex attributes and methods of specifying attributes using buffers, bufferViews, and accessors, except as otherwise noted.
  • GLB (binary glTF).
  • Node transform animation. One animation per animated property.
  • Morph target animation (position, normal, uv, tangent, color). One animation per animated property.
  • Metallic-Roughness materials.
  • Normal maps.
  • Occlusion maps.
  • Emissive maps.
  • Vertex colors.
  • UV clamping.
  • UV mirroring.
  • Specular Glossiness defined by the KHR_Materials_pbrSpecularGlossiness extension.
  • Textures using Basis Universal supercompression format, defined by the KHR_texture_basisu extension.

Unsupported features from the glTF specification

The features that are not currently supported from the glTF specification are as follows:

  • The glTF document scene must be set to a specific scene, or there must be exactly one scene in the glTF document.
  • Draco compression.
  • All glTF extensions except MSFT_lod and KHR_Materials_pbrSpecularGlossiness, as noted above.
  • Skins.
  • Primitive geometry types: POINTS, LINES, LINE_LOOP, and LINE_STRIP.
  • Cameras.
  • Multiple UV sets.
  • Sparse accessors.

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