Resolve issue where association mappings are missing for meshes when several glTF node definitions reference the same mesh data, and the mesh data has multiple primitives.Resolve issue where association mappings are missing for meshes when several glTF node definitions reference the same mesh data, and the mesh data has multiple primitives. (#22583)

examples/jsm/loaders/GLTFLoader.js

@@ -2369,6 +2369,27 @@ class GLTFParser {
 
 		const ref = object.clone();
 
+		// Propagates mappings to the cloned object, prevents mappings on the
+		// original object from being lost.
+		const updateMappings = ( original, clone ) => {
+
+			const mappings = this.associations.get( original );
+			if ( mappings != null ) {
+
+				this.associations.set( clone, mappings );
+
+			}
+
+			for ( const [ i, child ] of original.children.entries() ) {
+
+				updateMappings( child, clone.children[ i ] );
+
+			}
+
+		};
+
+		updateMappings( object, ref );
+
 		ref.name += '_instance_' + ( cache.uses[ index ] ++ );
 
 		return ref;
@@ -3848,12 +3869,46 @@ class GLTFParser {
 
 		for ( let i = 0, il = nodeIds.length; i < il; i ++ ) {
 
-			pending.push( buildNodeHierachy( nodeIds[ i ], scene, json, parser ) );
+			pending.push( buildNodeHierarchy( nodeIds[ i ], scene, json, parser ) );
 
 		}
 
 		return Promise.all( pending ).then( function () {
 
+			// Removes dangling associations, associations that reference a node that
+			// didn't make it into the scene.
+			const reduceAssociations = ( node ) => {
+
+				const reducedAssociations = new Map();
+
+				for ( const [ key, value ] of parser.associations ) {
+
+					if ( key instanceof Material || key instanceof Texture ) {
+
+						reducedAssociations.set( key, value );
+
+					}
+
+				}
+
+				node.traverse( ( node ) => {
+
+					const mappings = parser.associations.get( node );
+
+					if ( mappings != null ) {
+
+						reducedAssociations.set( node, mappings );
+
+					}
+
+				} );
+
+				return reducedAssociations;
+
+			};
+
+			parser.associations = reduceAssociations( scene );
+
 			return scene;
 
 		} );
@@ -3862,7 +3917,7 @@ class GLTFParser {
 
 }
 
-function buildNodeHierachy( nodeId, parentObject, json, parser ) {
+function buildNodeHierarchy( nodeId, parentObject, json, parser ) {
 
 	const nodeDef = json.nodes[ nodeId ];
 
@@ -3946,7 +4001,7 @@ function buildNodeHierachy( nodeId, parentObject, json, parser ) {
 			for ( let i = 0, il = children.length; i < il; i ++ ) {
 
 				const child = children[ i ];
-				pending.push( buildNodeHierachy( child, node, json, parser ) );
+				pending.push( buildNodeHierarchy( child, node, json, parser ) );
 
 			}