Extension of uniform quadratic B-spline curve

To facilitate the shape modification of uniform quadratic B-spline curve,the cubic polynomial blending functions are constructed using the requirements of uniform quadratic B-spline basis.It is an extension for the uniform quadratic B-spline basis functions.Based on the blending functions,the piecewise polynomial curves with shape parameters is built.By changing the values of the shape parameters,the shape of cubic polynomial curves can be adjusted and swing at the two sides of the uniform quadratic B-spline curve.The instance of the continuous curve with local adjusting parameter G1 is given.The method can enlarge the adjusting scale of uniform quadratic B-spline curve by adjusting the related parameters.