| 摘要 |
<p>In computer graphics a curved surface patch is defined in terms of a description of how a polygonal area in a parameter space maps onto the curved surface patch. To render the curved surface patch it is a approximated by a mesh of flat polygons. The cornerpoints of the polygons are points on the boundaries of the surface patch and points in the interior. The number of points on each boundary is selected as a function of the properties of that boundary only, and is the same no matter what shape the rest of the surface patch has. The parameter values of the points in the interior lie on a grid whose spacing is in line with the points on a first boundary that contains the most points of all boundaries. When it is detected that a second boundary contains as many points as the first boundary, the grid lines extend between points on the two boundaries. The points lie with even spacing along the lines of the grid and the coordinates of the points along each line are computed using forward differences.</p> |
