static void AppendGeometryCollection ( const [UGeometryCollection](API\Runtime\GeometryCollectionEngine\GeometryCollection\UGeometryCollection) * SourceGeometryCollection, const [TArray](API\Runtime\Core\Containers\TArray)< [UMaterialInterface](API\Runtime\Engine\Materials\UMaterialInterface) * > & Materials, const FTransform & GeometryCollectionTransform, [UGeometryCollection](API\Runtime\GeometryCollectionEngine\GeometryCollection\UGeometryCollection) * TargetGeometryCollectionObject, bool ReindexMaterials )