The following flags control vertex processing behavior for the hardware abstraction layer ( HAL ) and reference devices. 下面的标识为硬件抽象层和引用设备控制顶点(CV)处理的行为。
Movement of any control vertex affects three curve segments. 移动一个顶点仅影响三段曲线。
But surface generation requests through a series of curves, and it finally produces control vertex and node vector satisfied with surface request. 而蒙面曲面的生成则要求生成的曲面通过一系列的曲线,它最终生成曲面所需要的控制顶点(CV)和相应的节点矢量。
Meanwhile, the shape design with control vertex constructs curve which can meet the mathematics characteristic in need and guarantee the continuity of the first differential coefficient or above the second differential coefficient. 利用控制顶点(CV)进行形状设计,其所构造的曲线较易满足设计所需的数学特性,能保证曲线曲面连接处的一阶或二阶以上高阶导数的连续性。
In the article, with give surface control point and boundary condition, matrix expression is given using quadric NURBS surface. And the algorithm of control vertex is give to solve the inverse problem of quadric NURBS surface. 对于给定的曲面型值点及边界条件,本文利用二次NURBS曲面的矩阵表达式,给出一个反求二次NURBS曲面控制顶点(CV)的算法。