Update README.md

Add references to KHR_meshopt_compression; while it's currently a draft
it should be safe to use as the extension specification is more or less
final and no further changes in binary/JSON format are expected.

Author: zeux

README.md

@@ -332,7 +332,7 @@ Alternatively you can use general purpose compression libraries like zstd or Ood
 
 To that end, this library provides algorithms to "encode" vertex and index data. The result of the encoding is generally significantly smaller than initial data, and remains compressible with general purpose compressors - so you can either store encoded data directly (for modest compression ratios and maximum decoding performance), or further compress it with LZ4/zstd/Oodle to maximize compression ratio.
 
-> Note: this compression scheme is available as a glTF extension [EXT_meshopt_compression](https://github.com/KhronosGroup/glTF/blob/main/extensions/2.0/Vendor/EXT_meshopt_compression/README.md).
+> Note: this compression scheme is available as a glTF extension [EXT_meshopt_compression](https://github.com/KhronosGroup/glTF/blob/main/extensions/2.0/Vendor/EXT_meshopt_compression/README.md) as well as [KHR_meshopt_compression](https://github.com/KhronosGroup/glTF/pull/2517).
 
 ### Vertex compression
 

gltf/README.md

@@ -20,7 +20,7 @@ By default gltfpack outputs regular `.glb`/`.gltf` files that have been optimize
 
 When using `-c` option, gltfpack outputs compressed `.glb`/`.gltf` files that use meshoptimizer codecs to reduce the download size further. Loading these files requires extending GLTF loaders with support for [EXT_meshopt_compression](https://github.com/KhronosGroup/glTF/blob/main/extensions/2.0/Vendor/EXT_meshopt_compression/README.md) extension; three.js supports it in r122+ (requires calling `GLTFLoader.setMeshoptDecoder`), Babylon.js supports it in 5.0+ without further setup.
 
-For better compression, you can use `-cc` option which applies additional compression; additionally make sure that your content delivery method is configured to use deflate (gzip) - meshoptimizer codecs are designed to produce output that can be compressed further with general purpose compressors.
+For better compression, you can use `-cc` option which applies additional compression; additionally make sure that your content delivery method is configured to use deflate (gzip) - meshoptimizer codecs are designed to produce output that can be compressed further with general purpose compressors. For maximum compression, consider using [KHR_meshopt_compression](https://github.com/KhronosGroup/glTF/pull/2517) extension with a higher compression level (`-cz` option).
 
 gltfpack can also compress textures using Basis Universal format stored in a KTX2 container (`-tc` flag, requires support for `KHR_texture_basisu`) or using WebP format (`-tw` flag, requires support for `EXT_texture_webp`).
 
@@ -83,6 +83,7 @@ gltfpack supports most Khronos extensions and some multi-vendor extensions in th
 - KHR_materials_variants
 - KHR_materials_volume
 - KHR_mesh_quantization
+- KHR_meshopt_compression
 - KHR_texture_basisu
 - KHR_texture_transform
 - EXT_mesh_gpu_instancing
@@ -92,6 +93,7 @@ gltfpack supports most Khronos extensions and some multi-vendor extensions in th
 Even if the source file does not use extensions, gltfpack may use some extensions in the output file either by default or when certain options are used:
 
 - KHR_mesh_quantization (used by default unless disabled via `-noq`)
+- KHR_meshopt_compression (used when requested via `-ce khr` or `-cz`)
 - KHR_texture_transform (used by default when textures are present, unless disabled via `-noq` or `-vtf`)
 - KHR_texture_basisu (used when requested via `-tc` or `-tu`)
 - EXT_meshopt_compression (used when requested via `-c` or `-cc`)