专利名称：Parametric curve evaluation for a computer
graphics display system
发明人：Luken, William Louis, Jr.申请号：EP90311369.4申请日：19901017公开号：EP0425174A3公开日：19921007
专利附图：
摘要：A method and apparatus are described for evaluating and rendering parametriccurves. The apparatus includes a system memory connected to a pipelined arrangementof a graphics control processor, a plurality of parallel floating point processors, another
floating point processor, a clipping processor and a frame buffer. The method includes:organizing and storing of NURBS data in system memory as a sequence of data recordssuch that successive spans of a parametric curve of order k are defined by successiveindividual data records in conjunction with the immediately preceding 2k-3 prior datarecords; transforming the control points from modelling coordinates to view coordinates(x,y,z); multiplying the transformed control point coordinates by a weight yielding wx, wy,wz, w; simultaneously within each parallel floating point processor evaluating the b-splinefunctions for one component of the coordinate set (wx, wy, wz, w) for determinedparameter points; eliminating the weight from wx, wy, wz, w yielding geometriccoordinates x,y,z for points on the curve, clipping the geometric coordinates to thecurrent viewing boundaries and drawing the clipped vectors as straight line segments ona screen of a computer graphics display system.
申请人：International Business Machines Corporation
地址：Old Orchard Road Armonk, N.Y. 10504 US
国籍：US
代理机构：Burt, Roger James, Dr.
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