features.md

Features

glTFast requires Unity 2019.4 or newer.

Legend

• ✅ Fully supported
• ☑️ Partially supported
• ℹ️ Planned (click for issue)
• ⛔️ No plan to support (click for issue)
• ?: Unknown / Untested
• n/a: Not available

Platforms

All of Unity's platforms are supported. glTFast is tested or was reported to run on:

• WebGL
• iOS
• Android
• Windows
• macOS
• Linux
• Universal Windows Platform
• Lumin (Magic Leap)

Workflows

	Runtime	Editor (design-time)
GameObject
Import	✅️	✅
Export	ℹ️	1 ☑️
Entities (see DOTS)
Import	☑️	n/a
Export		n/a

¹: glTF export currently only works on Unity 2020.2 or newer.

Core glTF features

The glTF 2.0 specification is fully supported, with only a few minor remarks.

	Import	Export
Format
glTF (.gltf)	✅	✅
glTF-Binary (.glb)	✅	✅
Buffer
External URIs	✅	✅
GLB main buffer	✅	✅
Embed buffers or textures (base-64 encoded within JSON)	✅
meshoptimizer compression (via package)	✅
Basics
Scenes	✅	✅
Node hierarchies	✅	✅
Cameras	✅
Images
PNG	✅	✅
Jpeg	✅	✅
KTX with Basis Universal compression (via KtxUnity)	✅
Texture sampler
Filtering	✅ with limitations	✅ with limitations
Wrap modes	✅	✅
Materials Overview (see details)
Universal Render Pipeline (URP)	✅	☑️
High Definition Render Pipeline (HDRP)	✅	☑️
Built-in Render Pipeline	✅	☑️
Topologies / Primitive Types
TRIANGLES	✅	✅
POINTS	✅	✅
1LINES	✅	✅
LINE_STRIP	✅	✅
1LINE_LOOP	✅	✅
TRIANGLE_STRIP
TRIANGLE_FAN
Quads	n/a	✅ via triangulation
Meshes
Positions	✅	✅
Normals	✅	✅
Tangents	✅	✅
Texture coordinates / UV sets	✅	?
Three or more texture coordinates / UV sets	issue	?
Vertex colors	✅	?
Draco mesh compression (via DracoUnity)	✅
Implicit (no) indices	✅
Per primitive material	✅	✅
Joints (up to 4 per vertex)	✅
Weights (up to 4 per vertex)	✅
Morph Targets / Blend Shapes
Sparse accessors	2 ✅
Skins (sponsored by Embibe)	✅
Animation
via legacy Animation System	✅
via Playable API (issue)
via Mecanim (issue)

¹: Untested due to lack of demo files.

²: Not on all accessor types; morph targets and vertex positions only

Extensions

Official Khronos extensions

	Import	Export
Khronos
KHR_draco_mesh_compression	✅
KHR_materials_pbrSpecularGlossiness	✅
KHR_materials_unlit	✅	✅
KHR_texture_transform	✅	✅
KHR_mesh_quantization	✅
KHR_texture_basisu	✅
KHR_lights_punctual	✅
KHR_materials_clearcoat	ℹ️
KHR_materials_sheen	ℹ️
KHR_materials_transmission	ℹ️
KHR_materials_variants	ℹ️
KHR_materials_ior	ℹ️
KHR_materials_specular	ℹ️
KHR_materials_volume	ℹ️
KHR_xmp_json_ld	️
Vendor
1EXT_mesh_gpu_instancing	✅
EXT_meshopt_compression	✅
EXT_lights_image_based	ℹ️

¹: Without support for custom vertex attributes (e.g. _ID)

Not investigated yet:

• AGI_articulations
• AGI_stk_metadata
• CESIUM_primitive_outline
• MSFT_lod
• MSFT_packing_normalRoughnessMetallic
• MSFT_packing_occlusionRoughnessMetallic

Will not become supported (reason in brackets):

• KHR_xmp (archived; prefer KHR_xmp_json_ld)
• KHR_techniques_webgl (archived)
• ADOBE_materials_clearcoat_specular (prefer KHR_materials_clearcoat)
• ADOBE_materials_thin_transparency (prefer KHR_materials_transmission)
• EXT_texture_webp (prefer KTX/basisu)
• FB_geometry_metadata (prefer KTX_xmp)
• MSFT_texture_dds (prefer KTX/basisu)

Materials Details

Material Import

Material Feature	URP	HDRP	Built-In
PBR1 Metallic-Roughness	✅	✅	✅
PBR1 Specular-Glossiness	✅	✅	✅
Unlit	✅	✅	✅
Normal texture	✅	✅	✅
Occlusion texture	✅	✅	✅
Emission texture	✅	✅	✅
Alpha modes OPAQUE/MASK/BLEND	✅	✅	✅
Double sided / Two sided	✅	✅	✅
Vertex colors	✅	✅	✅
Multiple UV sets	✅2	✅2	✅2
Texture Transform	✅	✅	✅
Clear coat	ℹ️	ℹ️	⛔️
Sheen	ℹ️	ℹ️	⛔️
Transmission	☑️3	☑️4	☑️4
Variants	ℹ️	ℹ️	ℹ️
IOR	ℹ️	ℹ️	⛔️
Specular	ℹ️	ℹ️	⛔️
Volume	ℹ️	ℹ️	⛔️

¹: Physically-Based Rendering (PBR) material model

²: Two sets of texture coordinates (as required by the glTF 2.0 specification) are supported, but not three or more (issue)

³: There are two approximation implementations for transmission in Universal render pipeline. If the Opaque Texture is enabled (in the Universal RP Asset settings), it is sampled to provide proper transmissive filtering. The downside of this approach is transparent objects are not rendered on top of each other. If the opaque texture is not available, the common approximation (see ⁴ below) is used.

⁴: Transmission in Built-In and HD render pipeline does not support transmission textures and is only 100% correct in certain cases like clear glass (100% transmission, white base color). Otherwise it's an approximation.

Material Export

Material export is currently only tested on the following shaders:

• Universal and High Definition render pipeline
  • Lit
  • Unlit
• Built-In render pipeline
  • Standard
  • Unlit

Other shaders might (partially) work if they have similar properties (with identical names).

Material Feature	URP1	HDRP2	Built-In3
PBR Metallic-Roughness	✅	✅	✅
PBR Specular-Glossiness
Unlit	✅	✅	✅
Normal texture	✅	✅	✅
Occlusion texture	✅	✅	✅
Emission texture	✅	✅	✅
Alpha modes OPAQUE/MASK/BLEND	✅	✅	✅
Double sided / Two sided	✅	✅	✅
Vertex colors	?	?	?
Multiple UV sets	?	?	?
Texture Transform	✅	✅	✅
Clear coat			n/a
Sheen	?	?	n/a
Transmission			n/a
Variants
IOR			n/a
Specular
Volume			n/a

¹: Universal Render Pipeline Lit Shader

²: High Definition Render Pipeline Lit Shader

³: Built-In Render Pipeline Standard and Unlit Shader

Data-Oriented Technology Stack

⚠️ Note: DOTS is highly experimental and many features don't work yet. Do not use it for production ready projects!

Unity's Data-Oriented Technology Stack (DOTS) allows users to create high performance gameplay. glTFast has experimental import support for it.

Instead of traditional GameObjects, glTFast will instantiate Entities with Hybrid Renderer (version 2) components.

Possibly incomplete list of things that are known to not work with Entities yet:

• Animation
• Skinning
• Morph targets
• Cameras
• Lights

DOTS Setup

• First, go through the official DOTS project setup
• Make sure to enable Hybrid Renderer V2
• Use GltfEntityAsset instead of GltfAsset
• For customized behavior, use the EntityInstantiator instead of the GameObjectInstantiator