Mark several recently ratified extensions as complete, update registr…

…y. (#2304)

extensions/2.0/Khronos/KHR_materials_anisotropy/README.md

@@ -23,7 +23,7 @@ See [Appendix](#appendix-full-khronos-copyright-statement) for full Khronos Copy
 
 ## Status
 
-Release Candidate
+Complete, Ratified by the Khronos Group
 
 ## Dependencies
 

extensions/2.0/Vendor/EXT_mesh_gpu_instancing/README.md

@@ -8,7 +8,7 @@
 
 ## Status
 
-Experimental
+Complete, Ratified by the Khronos Group
 
 ## Dependencies
 

extensions/2.0/Vendor/EXT_meshopt_compression/README.md

@@ -7,7 +7,7 @@
 
 ## Status
 
-Complete
+Complete, Ratified by the Khronos Group
 
 ## Dependencies
 

extensions/2.0/Vendor/EXT_texture_webp/README.md

@@ -7,7 +7,7 @@
 
 ## Status
 
-Complete
+Complete, Ratified by the Khronos Group
 
 ## Dependencies
 

extensions/README.md

@@ -15,6 +15,7 @@ The following extensions have been ratified by the Khronos Group:
 
 * [KHR_draco_mesh_compression](2.0/Khronos/KHR_draco_mesh_compression/README.md)
 * [KHR_lights_punctual](2.0/Khronos/KHR_lights_punctual/README.md)
+* [KHR_materials_anisotropy](2.0/Khronos/KHR_materials_anisotropy/README.md)
 * [KHR_materials_clearcoat](2.0/Khronos/KHR_materials_clearcoat/README.md)
 * [KHR_materials_emissive_strength](2.0/Khronos/KHR_materials_emissive_strength/README.md)
 * [KHR_materials_ior](2.0/Khronos/KHR_materials_ior/README.md)
@@ -29,16 +30,16 @@ The following extensions have been ratified by the Khronos Group:
 * [KHR_texture_basisu](2.0/Khronos/KHR_texture_basisu/README.md)
 * [KHR_texture_transform](2.0/Khronos/KHR_texture_transform/README.md)
 * [KHR_xmp_json_ld](2.0/Khronos/KHR_xmp_json_ld/README.md)
+* [EXT_mesh_gpu_instancing](2.0/Vendor/EXT_mesh_gpu_instancing/README.md)
+* [EXT_meshopt_compression](2.0/Vendor/EXT_meshopt_compression/README.md)
+* [EXT_texture_webp](2.0/Vendor/EXT_texture_webp/README.md)
 
 ### Multi-Vendor Extensions for glTF 2.0
 
-When an extension is implemented by more than one vendor, its name can use the reserved `EXT` prefix. Multi-vendor extensions are not covered by the Khronos IP framework.
+When an extension is implemented by more than one vendor, its name can use the reserved `EXT` prefix. Multi-vendor extensions are typically not covered by the Khronos IP framework, with a few notable exceptions (listed above) that have been through the Khronos ratification process after becoming widely used under the `EXT` prefix.
 
 * [EXT_lights_ies](2.0/Vendor/EXT_lights_ies/README.md)
 * [EXT_lights_image_based](2.0/Vendor/EXT_lights_image_based/README.md)
-* [EXT_mesh_gpu_instancing](2.0/Vendor/EXT_mesh_gpu_instancing/README.md)
-* [EXT_meshopt_compression](2.0/Vendor/EXT_meshopt_compression/README.md)
-* [EXT_texture_webp](2.0/Vendor/EXT_texture_webp/README.md)
 
 ### Vendor Extensions for glTF 2.0
 
@@ -97,22 +98,9 @@ extensions, Khronos extensions, or inclusion in a future version of the glTF spe
 |-----------|--------|
 | [KHR_animation_pointer](https://github.com/KhronosGroup/glTF/pull/2147) | Ready for testing. |
 | [KHR_audio](https://github.com/KhronosGroup/glTF/pull/2137) | Ready for testing. |
-| [KHR_materials_anisotropy](https://github.com/KhronosGroup/glTF/pull/1798) | Ready for testing. |
 | [KHR_materials_diffuse_transmission](https://github.com/KhronosGroup/glTF/pull/1825) | Ready for testing. |
 | [KHR_materials_sss](https://github.com/KhronosGroup/glTF/pull/1928) | In development. |
 
-## Extensions for glTF 1.0
-
-### Khronos extensions for glTF 1.0
-
-* [KHR_binary_glTF](1.0/Khronos/KHR_binary_glTF/README.md)
-* [KHR_materials_common](1.0/Khronos/KHR_materials_common/README.md)
-
-### Vendor extensions for glTF 1.0
-
-* [CESIUM_RTC](1.0/Vendor/CESIUM_RTC/README.md)
-* [WEB3D_quantized_attributes](1.0/Vendor/WEB3D_quantized_attributes/README.md)
-
 # About glTF Extensions
 
 glTF extensions extend the base glTF model format.  Extensions can introduce new properties (including properties that reference external data, and the extension can define the format of those data), new parameter semantics, reserved IDs, and new container formats.  Extensions are written against a specific version of glTF and may be promoted to core glTF in a later glTF version.
@@ -147,15 +135,17 @@ All extensions used in a model are listed as strings in the top-level `extension
 ```json
 {
   "extensionsUsed": [
-    "KHR_materials_pbrSpecularGlossiness", "VENDOR_physics"
+    "KHR_draco_mesh_compression", "VENDOR_physics"
   ],
   "extensionsRequired": [
-    "KHR_materials_pbrSpecularGlossiness"
+    "KHR_draco_mesh_compression"
   ]
 }
 ```
 This allows an engine to quickly determine if it supports the extensions needed to render the model without inspecting the `extensions` property of all objects.
 
+An extension is considered _required_ if a typical glTF loader would fail to load the asset in the absence of support for that extension.  For example, any mesh compression extension must be listed as _required_ unless an uncompressed fallback mesh is provided with the asset.  Likewise, a texture image format extension must be listed as _required_ unless fallback textures in core formats (JPG, PNG) are also supplied. Typically, PBR or other kinds of material extensions should not be listed in _required_, because the core glTF material can be considered a valid fallback for these kinds of extensions, and such extensions will not cause a conformant glTF loader to fail.
+
 ## Creating Extensions
 
 To create a new extension, use the [extension template](Template.md) and open a pull request into this repo.  Make sure to add the extension to the glTF Extension Registry (top of this file).