Support KHR_texture_basisu extension

Cargo.toml

@@ -47,6 +47,7 @@ import = ["base64", "image", "urlencoding"]
 KHR_lights_punctual = ["gltf-json/KHR_lights_punctual"]
 KHR_materials_pbrSpecularGlossiness = ["gltf-json/KHR_materials_pbrSpecularGlossiness"]
 KHR_materials_unlit = ["gltf-json/KHR_materials_unlit"]
+KHR_texture_basisu = ["gltf-json/KHR_texture_basisu"]
 KHR_texture_transform = ["gltf-json/KHR_texture_transform"]
 KHR_materials_transmission = ["gltf-json/KHR_materials_transmission"]
 KHR_materials_ior = ["gltf-json/KHR_materials_ior"]

README.md

@@ -46,13 +46,14 @@ The following glTF extensions are supported by the crate:
 - `KHR_lights_punctual`
 - `KHR_materials_pbrSpecularGlossiness`
 - `KHR_materials_unlit`
+- `KHR_texture_basisu`
 - `KHR_texture_transform`
 - `KHR_materials_variants`
 - `KHR_materials_volume`
 - `KHR_materials_specular`
 - `KHR_materials_transmission`
 - `KHR_materials_ior`
-- `KHR_materials_emissive_strength `
+- `KHR_materials_emissive_strength`
 - `EXT_texture_webp`
 
 To use an extension, list its name in the `features` section.

gltf-json/Cargo.toml

@@ -28,6 +28,7 @@ KHR_materials_transmission = []
 KHR_materials_unlit = []
 KHR_materials_variants = []
 KHR_materials_volume = []
+KHR_texture_basisu = []
 KHR_texture_transform = []
 KHR_materials_emissive_strength = []
 EXT_texture_webp = []

gltf-json/src/extensions/mod.rs

@@ -44,6 +44,8 @@ pub const ENABLED_EXTENSIONS: &[&str] = &[
     "KHR_materials_pbrSpecularGlossiness",
     #[cfg(feature = "KHR_materials_unlit")]
     "KHR_materials_unlit",
+    #[cfg(feature = "KHR_texture_basisu")]
+    "KHR_texture_basisu",
     #[cfg(feature = "KHR_texture_transform")]
     "KHR_texture_transform",
     #[cfg(feature = "KHR_materials_transmission")]
@@ -53,8 +55,6 @@ pub const ENABLED_EXTENSIONS: &[&str] = &[
     #[cfg(feature = "KHR_materials_emissive_strength")]
     "KHR_materials_emissive_strength",
     // Allowlisted texture extensions. Processing is delegated to the user.
-    #[cfg(feature = "allow_empty_texture")]
-    "KHR_texture_basisu",
     #[cfg(feature = "EXT_texture_webp")]
     "EXT_texture_webp",
     #[cfg(feature = "allow_empty_texture")]
@@ -66,6 +66,7 @@ pub const SUPPORTED_EXTENSIONS: &[&str] = &[
     "KHR_lights_punctual",
     "KHR_materials_pbrSpecularGlossiness",
     "KHR_materials_unlit",
+    "KHR_texture_basisu",
     "KHR_texture_transform",
     "KHR_materials_transmission",
     "KHR_materials_ior",

gltf-json/src/extensions/texture.rs

@@ -1,6 +1,6 @@
 #[cfg(any(feature = "KHR_texture_transform", feature = "EXT_texture_webp"))]
 use crate::{extras::Extras, validation::Validate};
-#[cfg(feature = "EXT_texture_webp")]
+#[cfg(any(feature = "KHR_texture_basisu", feature = "EXT_texture_webp"))]
 use crate::{image, Index};
 
 use gltf_derive::Validate;
@@ -23,6 +23,10 @@ pub struct Texture {
     #[serde(default, flatten)]
     pub others: Map<String, Value>,
 
+    #[cfg(feature = "KHR_texture_basisu")]
+    #[serde(default, rename = "KHR_texture_basisu", skip_serializing_if = "Option::is_none")]
+    pub texture_basisu: Option<TextureBasisu>,
+
     #[cfg(feature = "EXT_texture_webp")]
     #[serde(
         default,
@@ -39,6 +43,13 @@ pub struct TextureWebp {
     pub source: Index<image::Image>,
 }
 
+#[cfg(feature = "KHR_texture_basisu")]
+#[derive(Clone, Debug, Deserialize, Serialize, Validate)]
+pub struct TextureBasisu {
+    /// The index of the image used by this texture.
+    pub source: Index<image::Image>,
+}
+
 #[derive(Clone, Debug, Default, Deserialize, Serialize, Validate)]
 /// Reference to a `Texture`.
 pub struct Info {

gltf-json/src/image.rs

@@ -7,6 +7,8 @@ use serde_derive::{Deserialize, Serialize};
 pub const VALID_MIME_TYPES: &[&str] = &[
     "image/jpeg",
     "image/png",
+    #[cfg(feature = "KHR_texture_basisu")]
+    "image/ktx2",
     #[cfg(feature = "EXT_texture_webp")]
     "image/webp",
 ];

gltf-json/src/texture.rs

@@ -223,6 +223,18 @@ impl Texture {
     pub fn primary_source(&self) -> Index<image::Image> {
         #[allow(unused_mut)]
         let mut source = self.source;
+        #[cfg(feature = "KHR_texture_basisu")]
+        {
+            if let Some(texture_basisu) = &self.extensions {
+                if let Some(texture_basisu) = &texture_basisu.texture_basisu {
+                    // Only use the basisu source if the source is not empty
+                    // Otherwise, fallback to whatever was there originally
+                    if !source_is_empty(&texture_basisu.source) {
+                        source = texture_basisu.source;
+                    }
+                }
+            }
+        }
         #[cfg(feature = "EXT_texture_webp")]
         {
             if let Some(texture_webp) = &self.extensions {