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公开(公告)号：CA2055057A1
公开(公告)日：1992-06-07
申请号：CA2055057
申请日：1991-11-06
Applicant: IBM
Inventor： ALBAUGH VIRGIL A , URQUHART ROBERT J
Abstract: AT9-90-029 FAST Z BUFFER INITIALIZE AND UPDATE METHOD A method is provided for initializing and updating a group of pixels contained on a display in blocks. A group of pixels is considered as a block and has a status word associated therewith. This status word maintains a running total of the maximum z value of any pixel contained within a group, or block of pixels. In this manner, once a block of pixels is rendered on to the display screen a comparison can be made between the current pixels being displayed and a group of pixels which are to be displayed. The minimum z value of the group of pixels to be displayed is compared with the maximum z value for the group of pixels currently being displayed. If the current maximum z value, as stored in the status word, is less than the minimum z value for the pixels to be displayed, then the group of pixels currently being displayed will all "win" when compared to the pixels in the group to be displayed. Thus, a full block bypass of the group of pixels to be displayed is implemented, thereby saving considerable time and overhead when compared to conventional z buffer systems that compare z values for each individual pixel.
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公开(公告)号：CA2043176C
公开(公告)日：1995-09-26
申请号：CA2043176
申请日：1991-05-24
Applicant: IBM
Inventor： ALBAUGH VIRGIL A , URQUHART ROBERT J
Abstract: A method and apparatus is provided which allows a computer graphics system to accurately determine the actual depth value for pixels on a display screen which lie at the same depth as an associated surface. The associated surface is identified such that the delta z value with respect to the x and y direction along the surface can be calculated. The present invention then determines whether the line being considered is contained within a surface, or is an edge lying between, and adjacent to two surfaces. If the line is contained within a surface, the delta z value is initially added to the known endpoints of the line and then successively added, in the incremental x or y directions, to the pixels selected to represent the line. If the line is an edge, and includes selected pixels which lie on both associated surfaces, a filter is invoked that prevents those pixels corresponding to the surface, other than the surface first being considered, from being processed. The pixels being considered are then drawn in the same manner as a line within a surface. In this manner, the actual z value for each selected pixel can be determined and any hidden line, hidden surface removal problems are eliminated.
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公开(公告)号：CA2043176A1
公开(公告)日：1991-12-30
申请号：CA2043176
申请日：1991-05-24
Applicant: IBM
Inventor： ALBAUGH VIRGIL A , URQUHART ROBERT J
Abstract: A method and apparatus is provided which allows a computer graphics system to accurately determine the actual depth value for pixels on a display screen which lie at the same depth as an associated surface. The associated surface is identified such that the delta z value with respect to the x and y direction along the surface can be calculated. The present invention then determines whether the line being considered is contained within a surface, or is an edge lying between, and adjacent to two surfaces. If the line is contained within a surface, the delta z value is initially added to the known endpoints of the line and then successively added, in the incremental x or y directions, to the pixels selected to represent the line. If the line is an edge, and includes selected pixels which lie on both associated surfaces, a filter is invoked that prevents those pixels corresponding to the surface, other than the surface first being considered, from being processed. The pixels being considered are then drawn in the same manner as a line within a surface. In this manner, the actual z value for each selected pixel can be determined and any hidden line, hidden surface removal problems are eliminated.
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