1. A computer-implemented method for interactively modifying a 3D object modeled by a geometry mesh, the method comprising: displaying the 3D object on a display; drawing an action line on a portion of the displayed 3D object where an action to be applied to the 3D object, in response to a user command specifying a start point and an end point, wherein the action line is placed on the portion of the displayed 3D object without binding the geometry mesh to a virtual skeleton; electronically receiving a user selection of an action to be applied to the 3D object; electronically receiving a user selection of a point associated with the action line; electronically detecting movement of a user input device with respect to the selected point; and electronically applying the selected action on at least a portion of the 3D object based on the detected movement of the user input device and with reference to the action line.