Add allow-empty-texture feature

Cargo.toml

@@ -38,6 +38,7 @@ version = "0.25"
 
 [features]
 default = ["import", "utils", "names"]
+allow-empty-texture = ["gltf-json/allow-empty-texture"]
 extensions = ["gltf-json/extensions"]
 extras = ["gltf-json/extras"]
 names = ["gltf-json/names"]

gltf-json/Cargo.toml

@@ -16,6 +16,7 @@ serde_json = { features = ["raw_value"], version = "1.0" }
 
 [features]
 default = []
+allow-empty-texture = []
 names = []
 extensions = []
 extras = []

gltf-json/src/extensions/mod.rs

@@ -52,6 +52,13 @@ pub const ENABLED_EXTENSIONS: &[&str] = &[
     "KHR_materials_ior",
     #[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 = "allow-empty-texture")]
+    "EXT_texture_webp",
+    #[cfg(feature = "allow-empty-texture")]
+    "MSFT_texture_dds",
 ];
 
 /// Names of glTF 2.0 extensions supported by the library.

gltf-json/src/texture.rs

@@ -1,5 +1,5 @@
-use crate::validation::{Checked, Error, Validate};
-use crate::{extensions, image, Extras, Index, Path, Root};
+use crate::validation::Checked;
+use crate::{extensions, image, Extras, Index};
 use gltf_derive::Validate;
 use serde::{de, ser};
 use serde_derive::{Deserialize, Serialize};
@@ -166,9 +166,14 @@ pub struct Sampler {
     pub extras: Extras,
 }
 
+#[cfg(feature = "allow-empty-texture")]
+pub type Source = Option<Index<image::Image>>;
+
+#[cfg(not(feature = "allow-empty-texture"))]
+pub type Source = Index<image::Image>;
+
 /// A texture and its sampler.
 #[derive(Clone, Debug, Deserialize, Serialize, Validate)]
-#[gltf(validate_hook = "texture_validate_hook")]
 pub struct Texture {
     /// Optional user-defined name for this object.
     #[cfg(feature = "names")]
@@ -180,8 +185,11 @@ pub struct Texture {
     pub sampler: Option<Index<Sampler>>,
 
     /// The index of the image used by this texture.
-    #[serde(skip_serializing_if = "Option::is_none")]
-    pub source: Option<Index<image::Image>>,
+    #[cfg_attr(
+        feature = "allow-empty-texture",
+        serde(skip_serializing_if = "Option::is_none")
+    )]
+    pub source: Source,
 
     /// Extension specific data.
     #[serde(default, skip_serializing_if = "Option::is_none")]
@@ -194,19 +202,6 @@ pub struct Texture {
     pub extras: Extras,
 }
 
-fn texture_validate_hook<P, R>(texture: &Texture, root: &Root, path: P, report: &mut R)
-where
-    P: Fn() -> Path,
-    R: FnMut(&dyn Fn() -> Path, Error),
-{
-    let source_path = || path().field("source");
-    if let Some(index) = texture.source.as_ref() {
-        index.validate(root, source_path, report);
-    } else {
-        report(&source_path, Error::Missing);
-    }
-}
-
 #[derive(Clone, Debug, Deserialize, Serialize, Validate)]
 /// Reference to a `Texture`.
 pub struct Info {

src/accessor/mod.rs

@@ -40,9 +40,10 @@
 //! for accessor in gltf.accessors() {
 //!     match (accessor.data_type(), accessor.dimensions()) {
 //!         (DataType::F32, Dimensions::Vec3) => {
-//!             let iter = Iter::<[f32; 3]>::new(accessor, get_buffer_data);
-//!             for item in iter {
-//!                 println!("{:?}", item);
+//!             if let Some(iter) = Iter::<[f32; 3]>::new(accessor, get_buffer_data) {
+//!                 for item in iter {
+//!                     println!("{:?}", item);
+//!                 }
 //!             }
 //!         }
 //!         _ => {},

src/texture.rs

@@ -1,6 +1,6 @@
 use crate::{image, Document};
 
-pub use json::texture::{MagFilter, MinFilter, WrappingMode};
+pub use json::texture::{MagFilter, MinFilter, Source, WrappingMode};
 #[cfg(feature = "extensions")]
 use serde_json::{Map, Value};
 
@@ -158,10 +158,20 @@ impl<'a> Texture<'a> {
     }
 
     /// Returns the image used by this texture.
+    #[cfg(feature = "allow-empty-texture")]
+    pub fn source(&self) -> Option<image::Image<'a>> {
+        self.json
+            .source
+            .as_ref()
+            .map(|index| self.document.images().nth(index.value()).unwrap())
+    }
+
+    /// Returns the image used by this texture.
+    #[cfg(not(feature = "allow-empty-texture"))]
     pub fn source(&self) -> image::Image<'a> {
         self.document
             .images()
-            .nth(self.json.source.unwrap().value())
+            .nth(self.json.source.value())
             .unwrap()
     }