/// <summary>
/// 获取参数对应点
/// </summary>
/// <param name="par">参数</param>
/// <returns>参数对应点</returns>
public Point2D GetPointAtParam(double par)
{
int span = Knots.FindSpan(par);
var nn = Knots.BasicFuns(span, par);
Point2D pt = new Point2D();
int id = span - Degree;
for (int i = 0; i <= Degree; i++)
{
pt += GetControlPointAt(id + i) * nn[i];
}
return(pt);
}
