根据输入的点，自动反算控制点并生成B样条曲线-According to the input point, auto inverse control points and generate B-spline curve

型值点反算控制点要解线性方程，画样条曲线，常用三次多项式参数曲线构造，保持一阶或二阶导数连续。-Data points Inverse control point to solving linear equations, draw splines, commonly cubic polynomial parametric curves constructed, maintained a first or second derivative continuous.