正则有理Bezier曲线的等距曲线算法

The Algorithm of Offset Curve of the Regular Rational Bé ziter Curve

通过利用改进的有理德卡斯特里奥算法求得正则有理ｎ次Ｂｅｚｉｅｒ曲线各点处的切矢，由此得到各点的单位法矢量，应用于求原始曲线的等距曲线，从而巧妙地解决了原始正则有理ｎ次Ｂｅｚｉｅｒ曲线上各点的单位法矢量难求的困难。该方法几何意义明显，算法简洁，实践效果比较好，最后本文给出了两个实例。

In this paper, we obtain the tanget vector at each point of the regular rational Be ziter curve of degree n by using the improved rational de Casteljau algorithm.Then we can get the unit normal vector at each point of the original curve. So we have Ingeniously overcome the difficulty that the unit normal vector is not easily to be solved at each point. This method has obvious geometric meaning. The algorithm is simple and the result is satisfactory in practice.