/// <summary>
/// 向量旋转
/// </summary>
/// <param name="angle"></param>
/// <returns></returns>
public static Double2 Rotate(Double2 a, double angle)
{
return(Matrix2x2.RotateMatrix(angle) * a);
}
/// <summary>
/// 返回逆时针旋转90度的向量
/// </summary>
/// <param name="inDirection"></param>
/// <returns></returns>
public static Double2 Perpendicular(Double2 inDirection)
{
return(Matrix2x2.RotateMatrix(MathUtil.kPI / 2) * inDirection);
}