Z-buffer tag memory organization

Claim 1

A method for clearing a portion of a Z-buffer in an imaging system which has an array of pixels, a frame buffer, and a graphics controller, said Z-buffer having page organized random access memory (RAM) with a plurality of memory pages and including an array of Z-buffer elements, and each Z-buffer element being associated with a respective pixel, said method comprising: storing Z value information in each of said Z-buffer elements; establishing a plurality of invalidity bits, each of said invalidity bits determining a valid or invalid state for a corresponding Z-buffer element; organizing the plurality of said invalidity bits so that each of said invalidity bits is located on the same page as the corresponding Z-buffer element, and wherein a plurality of invalidity bits are grouped within a data word; and writing binary information into a portion of the plurality of invalidity bits so as to invalidate the Z-buffer elements for the portion of the Z-buffer to be cleared.

Claim 2

A method for clearing a portion of a Z-buffer in an imaging system which has an array of pixels, a frame buffer, and a graphics controller, said Z-buffer having page organized random access memory (RAM) with a plurality of memory pages and including an array of Z-buffer elements, and each Z-buffer element being associated with a respective pixel, said method comprising: storing Z value information in each of said Z-buffer elements; establishing a plurality of invalidity bits, each of said invalidity bits determining a valid or invalid state for a corresponding Z-buffer element; organizing the plurality of said invalidity bits so that each of said invalidity bits is located on the same page as the corresponding Z-buffer element, and wherein a plurality of invalidity bits are grouped within a data word; and writing binary information into a portion of the plurality of invalidity bits so as to invalidate the Z-buffer elements for the portion of the Z-buffer to be cleared.

Claim 9

A method for clearing a portion of a Z-buffer in a raster scanned imaging system which has an array of pixels, a frame buffer, and a graphics controller, said Z-buffer having page organized random access memory (RAM) with a plurality of memory pages, each memory page including Z-buffer elements with each element being associated with a respective pixel, said method comprising: storing a first plurality of bits of information in each of the Z-buffer elements, said first plurality of bits of information representing Z-values for corresponding Z-buffer elements; establishing a plurality of invalidity bits, each of said invalidity bits corresponding to one of the Z-buffer elements so that each of said invalidity bits determines a valid or invalid state for a corresponding Z-buffer element; organizing the plurality of invalidity bits so that each of said invalidity bits is located on the same page as the corresponding Z-buffer element, and wherein a plurality of invalidity bits are grouped within one or more a data words; writing binary information into a portion of the plurality of invalidity bits so as to invalidate the Z-buffer elements for the portion of the Z-buffer to be cleared; and substituting a predetermined Z value for the existing Z-value found in the Z-buffer if a corresponding invalidity bit is invalid.

Claim 10

A method for clearing a portion of a Z-buffer in a raster scanned imaging system which has an array of pixels, a frame buffer, and a graphics controller, said Z-buffer having page organized random access memory (RAM) with a plurality of memory pages, each memory page including Z-buffer elements with each element being associated with a respective pixel, said method comprising: storing a first plurality of bits of information in each of the Z-buffer elements, said first plurality of bits of information representing Z-values for corresponding Z-buffer elements; establishing a plurality of invalidity bits, each of said invalidity bits corresponding to one of the Z-buffer elements so that each of said invalidity bits determines a valid or invalid state for a corresponding Z-buffer element; organizing the plurality of invalidity bits so that each of said invalidity bits is located on the same page as the corresponding Z-buffer element, and wherein a plurality of invalidity bits are grouped within one or more a data words; writing binary information into a portion of the plurality of invalidity bits so as to invalidate the Z-buffer elements for the portion of the Z-buffer to be cleared; and substituting a predetermined Z value for the existing Z-value found in the Z-buffer if a corresponding invalidity bit is invalid.

Claim 13

A method for establishing and organizing a plurality of invalidity bits for use in clearing a portion of a Z-buffer memory having random access memory (RAM), said method comprising: providing a plurality of memory pages of said Z-buffer, each page including Z-buffer elements for storing Z values for corresponding pixels; establishing a plurality of invalidity bits, each of said invalidity bits determining a valid or invalid state for a corresponding Z-buffer element; writing binary information into each of said invalidity bits; organizing said invalidity bits so that each of said invalidity bits and the corresponding Z-buffer elements are located on the same page, wherein a plurality of said invalidity bits are stored together as a group in one or more data words which are separate from the Z buffer elements and read prior to reading Z values for the corresponding pixels; and checking said invalidity bits and substituting a predetermined Z value for an existing Z value found in the Z-buffer if a corresponding invalidity bit is invalid.

Claim 14

A method for establishing and organizing a plurality of invalidity bits for use in clearing a portion of a Z-buffer memory having random access memory (RAM), said method comprising: providing a plurality of memory pages of said Z-buffer, each page including Z-buffer elements for storing Z values for corresponding pixels; establishing a plurality of invalidity bits, each of said invalidity bits determining a valid or invalid state for a corresponding Z-buffer element; writing binary information into each of said invalidity bits; organizing said invalidity bits so that each of said invalidity bits and the corresponding Z-buffer elements are located on the same page, wherein a plurality of said invalidity bits are stored together as a group in one or more data words which are separate from the Z buffer elements and read prior to reading Z values for the corresponding pixels; and checking said invalidity bits and substituting a predetermined Z value for an existing Z value found in the Z-buffer if a corresponding invalidity bit is invalid.

Claim 18

A system for clearing a portion of a Z-buffer in an imaging device, said system comprising: an array of pixels; a frame buffer; a graphics controller; a Z-buffer having page organized random access memory (RAM) with a plurality of memory pages, each memory page having a plurality of Z-buffer elements which are adapted to store Z values for a set of corresponding pixels; and a single invalidity bit established for each Z-buffer element so that each invalidity bit determines a valid or invalid state for a corresponding Z-buffer element, each of said invalidity bits being located on the same page as the corresponding Z-buffer elements so that the corresponding Z-buffers elements are validated or invalidated in response to the invalidity bits scanned on the same memory page, and wherein a plurality of the invalidity bits are grouped together in memory within a data word.

Claim 19

A system for clearing a portion of a Z-buffer in an imaging device, said system comprising: an array of pixels; a frame buffer; a graphics controller; a Z-buffer having page organized random access memory (RAM) with a plurality of memory pages, each memory page having a plurality of Z-buffer elements which are adapted to store Z values for a set of corresponding pixels; and a single invalidity bit established for each Z-buffer element so that each invalidity bit determines a valid or invalid state for a corresponding Z-buffer element, each of said invalidity bits being located on the same page as the corresponding Z-buffer elements so that the corresponding Z-buffers elements are validated or invalidated in response to the invalidity bits scanned on the same memory page, and wherein a plurality of the invalidity bits are grouped together in memory within a data word.

Claim 23

A method for clearing at least a portion of a Z-buffer in an imaging system which has an array of pixels, a frame buffer and a graphics controller, said Z-buffer having page organized random access memory (RAM) which contains a plurality of memory pages, each memory page having an array of Z-buffer elements which are associated with respective pixels, said method comprising: storing Z value information in the Z-buffer elements; establishing a plurality of validation bits, each of said validation bits determining a valid or invalid state for a corresponding Z-buffer element; organizing the plurality of validation bits so that each of said validation bits is located on the same page as the corresponding Z-buffer element, said validation bits being grouped within one or more data words; and reading the Z value information and validation bits.

Claim 24

A method for clearing at least a portion of a Z-buffer in an imaging system which has an array of pixels, a frame buffer and a graphics controller, said Z-buffer having page organized random access memory (RAM) which contains a plurality of memory pages, each memory page having an array of Z-buffer elements which are associated with respective pixels, said method comprising: storing Z value information in the Z-buffer elements; establishing a plurality of validation bits, each of said validation bits determining a valid or invalid state for a corresponding Z-buffer element; organizing the plurality of validation bits so that each of said validation bits is located on the same page as the corresponding Z-buffer element, said validation bits being grouped within one or more data words; and reading the Z value information and validation bits.