| 摘要 |
A method and apparatus are described for evaluating and rendering parametric curves. The apparatus includes a system memory connected to a pipelined arrangement of 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 records such that successive spans of a parametric curve of order k are defined by successive individual data records in conjunction with the immediately preceding 2k-3 prior data records; 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-spline functions for one component of the coordinate set (wx, wy, wz, w) for determined parameter points; eliminating the weight from wx, wy, wz, w yielding geometric coordinates x,y,z for points on the curve, clipping the geometric coordinates to the current viewing boundaries and drawing the clipped vectors as straight line segments on a screen of a computer graphics display system.
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