Export morphAttributes field only when it is not empty in BufferGeometry.toJSON

src/core/BufferGeometry.js

@@ -980,7 +980,7 @@ BufferGeometry.prototype = Object.assign( Object.create( EventDispatcher.prototy
 
 		}
 
-		data.data = { attributes: {}, morphAttributes: {} };
+		data.data = { attributes: {} };
 
 		var index = this.index;
 
@@ -1012,9 +1012,10 @@ BufferGeometry.prototype = Object.assign( Object.create( EventDispatcher.prototy
 
 		}
 
-		var morphAttributes = this.morphAttributes;
+		var morphAttributes = {};
+		var hasMorphAttributes = false;
 
-		for ( var key in morphAttributes ) {
+		for ( var key in this.morphAttributes ) {
 
 			var attributeArray = this.morphAttributes[ key ];
 
@@ -1034,10 +1035,18 @@ BufferGeometry.prototype = Object.assign( Object.create( EventDispatcher.prototy
 
 			}
 
-			data.data.morphAttributes[ key ] = array;
+			if ( array.length > 0 ) {
+
+				morphAttributes[ key ] = array;
+
+				hasMorphAttributes = true;
+
+			}
 
 		}
 
+		if ( hasMorphAttributes ) data.data.morphAttributes = morphAttributes;
+
 		var groups = this.groups;
 
 		if ( groups.length > 0 ) {

src/loaders/BufferGeometryLoader.js

@@ -57,24 +57,28 @@ Object.assign( BufferGeometryLoader.prototype, {
 
 		var morphAttributes = json.data.morphAttributes;
 
-		for ( var key in morphAttributes ) {
+		if ( morphAttributes ) {
 
-			var attributeArray = morphAttributes[ key ];
+			for ( var key in morphAttributes ) {
 
-			var array = [];
+				var attributeArray = morphAttributes[ key ];
 
-			for ( var i = 0, il = attributeArray.length; i < il; i ++ ) {
+				var array = [];
 
-				var attribute = attributeArray[ i ];
-				var typedArray = new TYPED_ARRAYS[ attribute.type ]( attribute.array );
+				for ( var i = 0, il = attributeArray.length; i < il; i ++ ) {
 
-				var bufferAttribute = new BufferAttribute( typedArray, attribute.itemSize, attribute.normalized );
-				if ( attribute.name !== undefined ) bufferAttribute.name = attribute.name;
-				array.push( bufferAttribute );
+					var attribute = attributeArray[ i ];
+					var typedArray = new TYPED_ARRAYS[ attribute.type ]( attribute.array );
 
-			}
+					var bufferAttribute = new BufferAttribute( typedArray, attribute.itemSize, attribute.normalized );
+					if ( attribute.name !== undefined ) bufferAttribute.name = attribute.name;
+					array.push( bufferAttribute );
+
+				}
 
-			geometry.morphAttributes[ key ] = array;
+				geometry.morphAttributes[ key ] = array;
+
+			}
 
 		}