Method and apparatus for pixel clipping source and destination windows in a graphics system
First Claim
1. A method of moving blocks of pixel data from a source area to a destination area within a frame buffer in a computer graphics system, said pixel data including a window identifier and a pixel identifier for each pixel, the method comprising the steps of:
- reading a block of pixel data from said source area into a memory according to a plurality of source tiles;
comparing pixel window identifiers read from the frame buffer with a pixel window identifier previously stored in the memory to determine whether the pixel window identifiers read from the frame buffer match the pixel window identifier previously stored in the memory;
discarding each pixel whose corresponding window identifier does not match the previously stored window identifier with which the corresponding window identifier was compared; and
updating the frame buffer with the pixel data not discarded, wherein the respective window identifiers each comprise a data indicative of one of a plurality of visible windows associated with said graphics system.
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Abstract
A method of moving blocks of pixel data, including window-identifying data, from a source area to a destination area within a frame buffer in a computer graphics system comprises the steps of: reading a block of pixel data from the source area into a pixel cache memory; combining source tiles with destination tiles in the cache; comparing pixel window identifiers read from the frame buffer with a pixel window identifier previously stored in the memory to determine whether the pixel window identifiers read from the frame buffer match the previously stored pixel window identifier; discarding each pixel whose corresponding window identifier does not match the previously stored window identifier; and updating the frame buffer with the pixel data not discarded.
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Citations
28 Claims
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1. A method of moving blocks of pixel data from a source area to a destination area within a frame buffer in a computer graphics system, said pixel data including a window identifier and a pixel identifier for each pixel, the method comprising the steps of:
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reading a block of pixel data from said source area into a memory according to a plurality of source tiles; comparing pixel window identifiers read from the frame buffer with a pixel window identifier previously stored in the memory to determine whether the pixel window identifiers read from the frame buffer match the pixel window identifier previously stored in the memory; discarding each pixel whose corresponding window identifier does not match the previously stored window identifier with which the corresponding window identifier was compared; and updating the frame buffer with the pixel data not discarded, wherein the respective window identifiers each comprise a data indicative of one of a plurality of visible windows associated with said graphics system. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of moving blocks of pixel data corresponding to graphics primitives between windows in a graphics frame buffer system comprising the steps of:
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addressing a source window on the frame buffer with a source window register having a source window identifier and a source pixel identifier, the source window identifier comprising data indicative of one of a plurality of visible windows associated with said graphics system; addressing a destination window on the frame buffer with a destination window register having a destination window identifier and a destination pixel identifier, the destination window identifier comprising data indicative of one of said visible windows associated with said graphics system; comparing the source window identifier with a previously stored source window identifier and the destination window identifier with a previously stored destination window identifier; discarding the destination pixels if the source comparison of destination comparison indicates that the source window identifier or destination window identifier does not match the previously stored identifier with which that source or destination window identifier was compared; and rendering to the frame buffer remaining source pixels on a destination window. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A system for moving data blocks from a source window to a destination window in a graphics system comprising:
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memory means for storing source window data and destination window data, the respective source and destination window data each being indicative of one of a plurality of visible windows associated with said graphics system; source window register means interfaced with the memory means for storing pixel value data and data indicating a pixel'"'"'s location within the source window; first comparator means interfaced with the source window register means for comparing the pixel value data with a source window identifier; destination window register means interfaced with the memory means for storing the pixel value data within the destination window; second comparator means interfaced with the destination window register means for comparing the pixel value data with a destination window identifier; and combining means interfaced with the first and second comparator means for determining whether source pixel can be moved to the destination window. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26)
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27. A computer graphics system, comprising:
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(a) a frame buffer, having a source area and a destination area, for storing pixel data, said pixel data including a window identifier and a pixel identifier for each pixel, said window identifiers each comprising data indicative of one of a plurality of visible windows associated with said graphics system; (b) a window cache, coupled to said frame buffer, comprising first and second memory areas; (c) means for reading a block of pixel data from said source area into said first memory area according to a plurality of source tiles; (d) means for reading a block of pixel data from said destination area into said second memory area according to a plurality of destination tiles; (e) means for comparing pixel window identifiers read from the frame buffer with a pixel window identifier previously stored in the memory to determine whether the pixel window identifiers read from the frame buffer match the pixel window identifier previously stored in the memory; (f) means for discarding each pixel whose corresponding window identifier does not match the previously stored window identifier with which the corresponding window identifier was compared; and (g) means for updating the frame buffer with the pixel data not discarded.
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28. A system for moving source pixel data from a source window to a destination window in a graphics system, the destination window containing destination pixel data, the system comprising:
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memory means for storing source window data and destination window data; source window register means interfaced with the memory means for storing a source window identifier comprising data indicative of one of a plurality of visible windows associated with said graphics system; first comparator means interfaced with the source window register means for comparing source pixel data with the source window identifier; destination window register means interfaced with the memory means for storing a destination window identifier comprising data indicative of one of said visible windows; second comparator means interfaced with the destination window register means for comparing destination pixel data with the destination window identifier; and combining means interfaced with the first and second comparator means for determining whether source pixels can be moved to the destination window.
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Specification