Abstract: In a graphics processing circuit, up to N sets of state data are stored in a buffer such that a total length of the N sets of state data does not exceed the total length of the buffer. When a length of additional state data would exceed a length of available space in the buffer, storage of the additional set of state data in the buffer is delayed until at least M of the N sets of state data are no longer being used to process graphics primitives, wherein M is less than or equal to N. The buffer is preferably implemented as a ring buffer, thereby minimizing the impact of state data updates. To further prevent corruption of state data, additional sets of state data are prohibited from being added to the buffer if a maximum number of allowed states is already stored in the buffer.

Abstract: The occurrence of an (n+m) input operand instruction that requires more than n of its input operands from an n-output data source is recognized by a programmable vertex shader (PVS) controller. In turn, the PVS controller provides at least two substitute instructions, neither of which requires more than n operands from the n output data source, to a PVS engine. A first of the substitute instructions is executed by the PVS engine to provide an intermediate result that is temporarily stored and used as an input to another of the at least two substitute instructions. In this manner, the present invention avoids the expense of additional or significantly modified memory. In one embodiment of the present invention, a pre-accumulator register internal to the PVS engine is used to store the intermediate result. In this manner, the present invention provides a relatively inexpensive solution for a relatively infrequent occurrence.

Abstract: The occurrence of an (n+m) input operand instruction that requires more than n of its input operands from an n-output data source is recognized by a programmable vertex shader (PVS) controller. In turn, the PVS controller provides at least two substitute instructions, neither of which requires more than n operands from the n output data source, to a PVS engine. A first of the substitute instructions is executed by the PVS engine to provide an intermediate result that is temporarily stored and used as an input to another of the at least two substitute instructions. In this manner, the present invention avoids the expense of additional or significantly modified memory. In one embodiment of the present invention, a pre-accumulator register internal to the PVS engine is used to store the intermediate result. In this manner, the present invention provides a relatively inexpensive solution for a relatively infrequent occurrence.

Abstract: In a graphics processing circuit, up to N states of state data are stored in a buffer such that a total length of the N sets of state data does not exceed the total length of the buffer. When a length of additional state data would exceed a length of available space in the buffer, storage of the additional set of state data in the buffer is delayed until at least M of the N sets of state data are no longer being used to process graphics primitives, wherein M is less than or equal to N. The buffer is preferably implemented as a ring buffer, thereby minimizing the impact of state data updates. To further prevent corruption of state data, additional sets of state data are prohibited from being added to the buffer if a maximum number of allowed states is already stored in the buffer.

Abstract: A method and apparatus for clipping an object element include processing that begins by ascribing barycentric coordinates to each original vertices of an object-element wherein each barycentric coordinate is a weighting factor with respect to a corresponding original vertex. The processing continues by obtaining clipping distances for each original vertex with respect to a clipping plane. For a new vertex of an object-element that represents an intersection of an edge of the object-element with the clipping plane, the process continues by determining a barycentric coordinate for the new vertex. The determination of the new vertex is based on the barycentric coordinates of the original vertices defining the edge and the clipping distances. Having determined the barycentric coordinates for the new vertices corresponding to a clipping plane, the process is repeated for each of a plurality of other clipping planes that intersect the object-element.

Abstract: An apparatus and method for controlling the operation of a system are provided. The overall system operation is described by a plurality of mechanism cycles of operation each defined by a sequence of instructions relating sensed conditions of input devices, selectable conditions of output devices and variable values. Instruction signals representing the instructions of the sequences are stored together with mechanism cycle status signals each representing the executability of the associated mechanism cycle. Only instructions associated with cycles for which the status signal represent an executable condition are executed. Instructions for cycles for which the status signals represent a nonexecutable condition are modifiable during execution of the other instruction sequence. The instruction signals include variable name signals associated with unique interface circuits connected to the input and output devices.

Abstract: A method is disclosed for modifying coordinate data in a machining program in response to workpiece measurements made by a programmably controlled surface sensing element. The location of the workpiece and position of workpiece characteristics are determined by a series of programmed scanning cycles. The maximum, minimum and average measured positions of points on a workpiece surface are stored and may be used to calculate position offsets which may be used to modify a machining program. Further, the measured positions and offsets may be tested against programmed maximum and minimum limits to determine if the measured positions are within a tolerance band. In one embodiment, the positions of points on the workpiece surface are measured by a cutting tool operating in conjunction with a torque measuring circuit.

Abstract: A method is disclosed for detecting the presence of a workpiece characteristic and controlling the sequence of execution of operational steps in a machining program. First instructions in a machining program cause a sensing element to execute a scanning cycle to detect workpiece characteristics. Second instructions in the machining program test for the presence of the workpiece characteristics to determine the next operational step to be executed. The next operational step may be sequentially located in the program or may be identified by third instructions which define a nonsequential program location. Jump instructions are also provided to execute an unconditional jump to operational steps defined by a jump location instruction in the program.