其实任何维度的曲线（包括直线）都是单参数方程来描述的：x=x(t) ;y=y(t); z=z(t). 贝塞尔曲线也是这样的。只是它具有良好的光滑性，以及对于局(In fact, any dimension curve (including straight line) are single parameter equations: x=x (T); y=y (T); z=z (T). The Bessel curve is the same. But it has good smoothness, as well as for the Bureau)