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Engine features

Choose a material aspect or rendering capability, learn its public API, and explore it in a live glTF sample. These features belong to the engine and shared shader modules; glTF is one way to author and exchange them. Each page describes glTF core or extension support separately.

Surface appearance​

  • Metallic and rough surfaces — Base color, metallic response, and roughness describe surfaces ranging from matte dielectrics to polished metals.

  • Unlit surfaces — Unlit surfaces preserve their surface color without evaluating scene lighting, useful for signs, diagrams, and baked artwork.

  • Emissive surfaces — Emission makes a surface contribute its own visible radiance, including values above the display white level.

  • Specular reflection — Specular reflection controls the strength and tint of dielectric highlights independently of the base diffuse color.

  • Index of refraction — Index of refraction controls the optical contrast at a dielectric boundary and influences reflection and transmitted light.

  • Transmission, volume, and dispersion — Transparent materials transmit light through a surface; thickness, absorption, and wavelength separation describe glass and colored volumes.

  • Clearcoat — Clearcoat adds a secondary glossy layer over a base surface, useful for varnish, lacquer, and automotive paint.

  • Sheen — Sheen adds a soft grazing-angle response for fabric, velvet, and other surfaces with fine fibers.

  • Iridescence — Thin-film interference produces view-dependent colors, useful for coated glass, soap films, and decorative finishes.

  • Anisotropic reflection — Anisotropic reflection stretches highlights along a surface direction, useful for brushed metal and directional surface finishes.

  • Normal and bump mapping — Normal and height textures add apparent fine surface detail without increasing mesh tessellation.

  • Diffuse transmission and scattering — Diffuse transmission lets light emerge from the opposite side of a thin or scattering surface, useful for leaves, paper, and translucent ceramics.

  • Texture coordinates and transforms — Independent texture coordinate sets and transforms let each surface map use its own placement, rotation, and scale.

  • Base color

  • Opacity and cutouts

  • Double-sided surfaces

  • Ambient occlusion

  • Normal mapping

  • Emissive strength

  • Volume absorption

  • Dispersion

Scene capabilities and asset delivery​

  • Material variants — Material variants switch authored surface appearances while preserving the scene hierarchy and model identities.

  • Animation and deformation — Animation combines clip playback, skeletal deformation, and morph targets to bring characters and scene objects to life.

  • Mesh instancing — Instancing draws many placements of shared geometry with one draw per compatible primitive instead of duplicating models.

  • Punctual lighting — Directional, point, and spot lights provide explicit scene illumination with controllable direction, intensity, and color.

  • Compressed geometry and textures — Compressed geometry and textures reduce asset transfer size and can reduce GPU texture storage when the device supports the resulting format.

  • Scene visibility — Hide a scene subtree while preserving its hierarchy and resources for later reuse.

  • Animated crowds and levels of detail — Render independently animated characters with shared GPU geometry and select mesh detail by projected screen size.

glTF integration reference​

The format-focused documentation remains the source for import contracts and support details: