Abstract: The invention provides for a system and method for minimizing space requirements and increasing speed in a geometry accelerator for a computer graphics system. In architecture, the system is implemented as follows. The geometry accelerator includes a plurality of processing elements (e.g., an arithmetic logic unit, a multiplier, a divider, a compare mechanism, a clamp mechanism, etc.) and a plurality of control units (e.g., a transform mechanism, a decomposition mechanism, a clip mechanism, a bow-tie mechanism, a light mechanism, a classify mechanism, a plane equation mechanism, a fog mechanism, etc.) that utilize the processing elements for performing data manipulations upon image data. In accordance with the invention, the control units are implemented in a read-only memory (ROM) via microcode. A next address field is associated with each of the microcode instructions and defines a location in the ROM of a next instruction to be executed.

Abstract: A system and method computes the color of a plurality of vertices of one or more graphic primitives in a graphics accelerator. The method includes the steps of receiving lighting properties of a primitive vertex and determining whether predetermined lighting properties of the vertex are the same as a previously computed vertex. If predetermined lighting properties are the same as the previously computed vertex, then the method retrieves at least one preprocessed value from a storage location; and utilizes the at least one preprocessed value to compute the vertex color. If, however, the predetermined lighting properties are not the same as the previously computed vertex, then the method computes at least one preprocessed value from the received lighting properties of the primitive vertex, stores the at least one computed preprocessed value in a storage location, and utilizes the at least one preprocessed value to compute the vertex color. The system includes at least one processing unit (e.g.

Abstract: A novel system and method computes a floating point value of an exponential expression in the form of "a.sup.x " in a geometry accelerator. In accordance with one aspect of the invention, the method includes the steps of receiving the values "a" and x of the exponential expression, where both "a" and x are represented in floating point format. As will be appreciated by those skilled in the art, the values will by supplied by software through an appropriate graphics application program interface (API). The method utilizes a mantissa value of the floating point representation of "a" to index a first value in a first look-up table, the value being an approximation for log2(a). Then, the method multiplies the looked-up value by the value of x to obtain an intermediate result. This intermediate result is then partitioned into a fractional component and an integer component, wherein the fractional component is normalized/converted to floating point format.

Abstract: A method computes exponentials of a lighting equation in a geometry accelerator. In accordance with one aspect of the invention, the method includes the steps of receiving values for a first term "a" and a second term "x" of an exponential in the form a.sup.x. The method then evaluates at least one of the first and second terms to determine whether it is an integer value. If the evaluating step determines that the at least one of the terms is an integer value, then the method sets a bit in a memory location. Thereafter, the method examines a bit in the memory location. If the bit is set, then the invention executes an integer exponentiation routine to calculate a.sup.x directly in the math core. If, however, the bit is not set, then the invention executes a floating point exponentiation routine to closely approximate the calculation of a.sup.x.

Abstract: The present invention provides a method and apparatus for processing primitives in a computer graphics display system. The present invention comprises a geometry accelerator for processing polygons to provide two-sided lighting for front and back facing polygons. The geometry accelerator comprises a lighting machine and a memory device in communication with the lighting machine. The geometry accelerator receives command data, vertex data, and parameter data from a central processing unit (CPU) of a computer graphics display system. The vertex data comprises polygon vertex color data, vertex coordinate data and vertex normal data. The parameter data comprises front and back material parameters. The command data comprises information relating to the type of primitive to be processed by the lighting machine.

Abstract: A method and apparatus for managing texture mapping data in a computer graphics system, the system including a host computer, primitive rendering hardware and a textured primitive data path extending between the host computer and the primitive rendering hardware. The host computer passes textured primitives to be rendered by the system using corresponding texture mapping data to the primitive rendering hardware over the textured primitive data path. The host computer has a main memory that stores texture mapping data corresponding to the textured primitives to be rendered. The primitive rendering hardware includes a local texture memory that locally stores the texture mapping data corresponding to at least one of the textured primitives to be rendered.

Abstract: Ultra-oriented, crystalline synthetic filaments with a combination of high tenacity, high dimensional stability, high modulus, and a high fraction of taut-tie molecular phase are produced by extruding a fiber-forming synthetic polymer melt into a liquid isothermal bath, withdrawing the filaments from the bath and then post-treating them at a very low draw ratio. The bath is preferably maintained at a temperature of at least 30.degree. C. above the glass transition temperature of the polymer to enhance the orientation and promote the formation of stable extended chains. Polymer filaments so produced are characterized in that they have ultra-high birefringence, high tenacity and modulus, a high dimensional stability, and a high fraction of taut-tie molecular phase.

Abstract: Ultra-oriented, crystalline synthetic filaments with high tenacity are produced by extrusion of a fiber-forming synthetic polymer melt into a liquid isothermal bath maintained at a temperature of at least 30.degree. C. above the glass transition temperature of the polymer, withdrawing the filaments from the bath and then winding up the filaments. Polymer filaments so produced are characterized in that the ratio of the crystalline orientation factor (f.sub.c) to the amorphous orientation factor (f.sub.a) is 1.2 or less, and are further characterized in that the percent crystallinity is less than 40. The filaments also have a fine crystal size. The crystal size is less than 40 .ANG. in the 100 and 105 planes and less than 30 .ANG. in the 010 plane.

Abstract: Ultra-oriented, crystalline synthetic filaments with high tenacity are produced by extrusion of a fiber-forming synthetic polymer melt into a liquid isothermal bath maintained at a temperature of at least 30.degree. C. above the glass transition temperature of the polymer, withdrawing the filaments from the bath and then winding up the filaments. Polyethylene terephthalate filaments so produced at 3000-5000 m/min exhibit a crystalline structure and possess birefringence of 0.20-0.22, tenacity of 7-9 g/d, break elongation of 14-30% and boil-off shrinkage of 5-10%.

Abstract: The invention provides improved thermoplastic high strength, highly oriented fibers and a process for producing the fibers by melt spinning a thermoplastic polymer to form a threadline, preferably passing the threadline through a thermal conditioning zone and then quenching the threadline. The quenched threadline is passed through a hydraulic drag bath maintained at a temperature of greater than the glass transition temperature of the polymer which substantially increases the threadline stress and results in drawing of the threadline. The threadline is withdrawn from the drag bath at a withdrawal rate of at least 3,000 meters per minute.

Abstract: Ultra-oriented, crystalline synthetic filaments with high tenacity are produced by extrusion of a fiber-forming synthetic polymer melt into a liquid isothermal bath maintained at a temperature of at least 30.degree. C. above the glass transition temperature of the polymer, withdrawing the filaments from the bath and then winding up the filaments. Polyethylene terephthalate filaments so produced at 3000-5000 m/min exhibit a crystalline structure and possess birefringence of 0.20-0.22, tenacity of 7-9 g/d, break elongation of 14%-30% and boil-off shrinkage of 5%-10%.

Abstract: The high speed melt spinning of synthetic polymer fibers is provided with on-line zone heating and cooling by which the strand emerging from the spinneret is initially cooled to an optimum temperature above the glass transition point of the polymer, the maintained near that temperature for a period of time to promote development of desirable fiber properties such as crystallization and crystal orientation, and then finally cooled below the solidification point for take up.

Abstract: A gas flow controller 10 for use with a molecular sieve type oxygen enrichment of air system 5 delivering oxygen enriched air for breathing by aircrew ensures that a constant preset quantity of product gas in the form of oxygen enriched air flows from the system 5 so that it performs under varying demand conditions and varying air supply conditions to maintain desired levels of oxygen concentration in the oxygen enriched air delivered to the aircrew by means of a demand regulator 6 and a breathing mask 7. A servo-operated valve means 20 bleeds air from downstream of a venturi section 15 provided between in the inlet 13 and outlet 14 of a gas flow duct 12 in the body 11 of the controller 10. The servo-operated valve means 20 is regulated by an actuator means 29 responsive to pressure difference through the venturi section 15.

Abstract: An artificial leg has a stabilized knee mechanism, that is, a mechanism which resists flexion of the leg when the latter is under load. The leg has upper and lower leg components, for example thigh and shin, and the knee mechanism includes a hollow brake drum with a brake shoe inside it. The drum is connected to the thigh and the shoe to the shin. The shoe frictionally engages the inner surface of the drum to resist flexion of the leg when it is under load.

Abstract: An artificial leg has a stabilized knee mechanism, that is, a mechanism which resists flexion of the leg when the latter is under load. The leg has upper and lower leg components, for example thigh and shin, and the knee mechanism includes a hollow brake drum with a brake shoe inside it. The drum is connected to the thigh and the shoe to the shin. The shoe frictionally engages the inner surface of the drum to resist flexion of the leg when it is under load.

Abstract: Ultra-oriented, crystalline synthetic filaments with high tenacity are produced by extrusion of a fiber-forming synthetic polymer melt into a liquid isothermal bath maintained at a temperature of at least 30.degree. C. above the glass transition temperature of the polymer, withdrawing the filaments from the bath and then winding up the filaments. Polymer filaments so produced are characterized in that the ratio of the crystalline orientation factor (f.sub.c) to the amorphous orientation factor (f.sub.a) is 1.2 or less, and are further characterized in that the percent crystallinity is less than 40. The filaments also have a fine crystal size. The crystal size is less than 40 .ANG. in the 100 and 105 planes and less than 30 .ANG. in the 010 plane.