code: function () {
          var localTransform = this.localTransform.array;
          var worldTransform = this.worldTransform.array;
          if (this._parent) {
              mat4.multiplyAffine(
                  worldTransform,
                  this._parent.worldTransform.array,
                  localTransform
              );
          }
          else {
              mat4.copy(worldTransform, localTransform);
          }
      }
docs: Update world transform, assume its parent world transform have been updated
  @private