Abstract: A graphical interface for visually specifying the behavior of combinations of finite-state and continuous-state actors. The state of an actor may be controlled by the states of other actors. The motion of continuous-state actors is constrained by functions represented as, and analogous to, grooves, sockets, pins, glue, springs, and boxes. These functions may be represented graphically on the actor so that the system of constraints is readily ascertainable to the user.

Abstract: A method and apparatus for direct manipulation of 3-D objects on computer display. This method and apparatus provides for a 3-D bounding region wherein the 3-D bounding region has sensitive areas which the user can select with a reference pointer such that when the user manipulates the reference pointer after selecting a sensitive area the 3-D bounding region and the object within it are manipulated with direct kinesthetic correspondence between the user's manipulation of the reference pointer and the bounding region and object manipulation.

Abstract: A photovoltaic relay which includes a unique pull down circuit for rapidly turning off the relays field effect transistor(s). The pull down circuit discharges the gate-to-source capacitance of the relay's field effect transistors by turning on a thyristor by turning off a light-activated switch connected between the gate and the cathode terminals of the thyristor. In one integrated circuit embodiment, the light-activated switch is energized by the same light source which activates the photodiode stack which drives the relay. The presence of the pull down circuit does not effect the turn on time of the relay.