Add get_supported_gltf_extensions to GLTFDocument

modules/gltf/doc_classes/GLTFDocument.xml

@@ -63,6 +63,13 @@
 				The [param bake_fps] parameter overrides the bake_fps in [param state].
 			</description>
 		</method>
+		<method name="get_supported_gltf_extensions" qualifiers="static">
+			<return type="PackedStringArray" />
+			<description>
+				Returns a list of all support glTF extensions, including extensions supported directly by the engine, and extensions supported by user plugins registering [GLTFDocumentExtension] classes.
+				[b]Note:[/b] If this method is run before a GLTFDocumentExtension is registered, its extensions won't be included in the list. Be sure to only run this method after all extensions are registered. If you run this when the engine starts, consider waiting a frame before calling this method to ensure all extensions are registered.
+			</description>
+		</method>
 		<method name="register_gltf_document_extension" qualifiers="static">
 			<return type="void" />
 			<param index="0" name="extension" type="GLTFDocumentExtension" />

modules/gltf/gltf_document.cpp

@@ -7060,6 +7060,8 @@ void GLTFDocument::_bind_methods() {
 			&GLTFDocument::register_gltf_document_extension, DEFVAL(false));
 	ClassDB::bind_static_method("GLTFDocument", D_METHOD("unregister_gltf_document_extension", "extension"),
 			&GLTFDocument::unregister_gltf_document_extension);
+	ClassDB::bind_static_method("GLTFDocument", D_METHOD("get_supported_gltf_extensions"),
+			&GLTFDocument::get_supported_gltf_extensions);
 }
 
 void GLTFDocument::_build_parent_hierachy(Ref<GLTFState> p_state) {
@@ -7100,6 +7102,36 @@ Vector<Ref<GLTFDocumentExtension>> GLTFDocument::get_all_gltf_document_extension
 	return all_document_extensions;
 }
 
+Vector<String> GLTFDocument::get_supported_gltf_extensions() {
+	HashSet<String> set = get_supported_gltf_extensions_hashset();
+	Vector<String> vec;
+	for (const String &s : set) {
+		vec.append(s);
+	}
+	vec.sort();
+	return vec;
+}
+
+HashSet<String> GLTFDocument::get_supported_gltf_extensions_hashset() {
+	HashSet<String> supported_extensions;
+	// If the extension is supported directly in GLTFDocument, list it here.
+	// Other built-in extensions are supported by GLTFDocumentExtension classes.
+	supported_extensions.insert("GODOT_single_root");
+	supported_extensions.insert("KHR_lights_punctual");
+	supported_extensions.insert("KHR_materials_emissive_strength");
+	supported_extensions.insert("KHR_materials_pbrSpecularGlossiness");
+	supported_extensions.insert("KHR_materials_unlit");
+	supported_extensions.insert("KHR_texture_transform");
+	for (Ref<GLTFDocumentExtension> ext : all_document_extensions) {
+		ERR_CONTINUE(ext.is_null());
+		Vector<String> ext_supported_extensions = ext->get_supported_extensions();
+		for (int i = 0; i < ext_supported_extensions.size(); ++i) {
+			supported_extensions.insert(ext_supported_extensions[i]);
+		}
+	}
+	return supported_extensions;
+}
+
 PackedByteArray GLTFDocument::_serialize_glb_buffer(Ref<GLTFState> p_state, Error *r_err) {
 	Error err = _encode_buffer_glb(p_state, "");
 	if (r_err) {
@@ -7452,19 +7484,7 @@ Error GLTFDocument::_parse_gltf_extensions(Ref<GLTFState> p_state) {
 		Vector<String> ext_array = p_state->json["extensionsRequired"];
 		p_state->extensions_required = ext_array;
 	}
-	HashSet<String> supported_extensions;
+	HashSet<String> supported_extensions = get_supported_gltf_extensions_hashset();
-	supported_extensions.insert("KHR_lights_punctual");
-	supported_extensions.insert("KHR_materials_pbrSpecularGlossiness");
-	supported_extensions.insert("KHR_texture_transform");
-	supported_extensions.insert("KHR_materials_unlit");
-	supported_extensions.insert("KHR_materials_emissive_strength");
-	for (Ref<GLTFDocumentExtension> ext : document_extensions) {
-		ERR_CONTINUE(ext.is_null());
-		Vector<String> ext_supported_extensions = ext->get_supported_extensions();
-		for (int i = 0; i < ext_supported_extensions.size(); ++i) {
-			supported_extensions.insert(ext_supported_extensions[i]);
-		}
-	}
 	Error ret = OK;
 	for (int i = 0; i < p_state->extensions_required.size(); i++) {
 		if (!supported_extensions.has(p_state->extensions_required[i])) {

modules/gltf/gltf_document.h

@@ -92,6 +92,8 @@ public:
 	static void unregister_gltf_document_extension(Ref<GLTFDocumentExtension> p_extension);
 	static void unregister_all_gltf_document_extensions();
 	static Vector<Ref<GLTFDocumentExtension>> get_all_gltf_document_extensions();
+	static Vector<String> get_supported_gltf_extensions();
+	static HashSet<String> get_supported_gltf_extensions_hashset();
 
 	void set_naming_version(int p_version);
 	int get_naming_version() const;