Boots – shoes – and leggings
Patent
1987-02-05
1991-03-12
Shaw, Dale M.
Boots, shoes, and leggings
364521, 364522, 340729, 340747, G06F 1562
Patent
active
049997890
ABSTRACT:
A graphics accelerator responds to commands from a computer in a graphic system by storing the definitions of nonuniform rational B-spline patches and their associated trimming curves. The graphics accelerator then produces device coordinates for trimmed polygons computed for each patch and sends these polygons to a display. The B-spline definitions of the trimming curves in the uv parameter space of each patch are converted to approximating short straight line segments. Untrimmed polygon vertices, the end points of the straight line segments and the intersections of the straight line segments with subspan boundaries corresponding to polygon edges are kept in a data structure of linked lists of vertex tables. The data structure is traversed to determine new polygon vertices for trimmed polygons. The trimming mechanism is compatible with recursive subdivision of patches to overcome practical limitations on the number of trimming curves that may be associated with each patch. The length of the straight line segments of the trimming curves is adjusted to compensate for less than ideal parameterization of the trimming curve functions. Associated with each trimming curve within a patch is information about the position of that trimming curve in the span. As each polygon for that patch is generated, those trimming curves that are clearly outside the clip limits for that polygon are excluded from consideration.
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Hewlett-Packard Co.
Miller Edward L.
Nguyen Phu K.
Shaw Dale M.
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