/// <summary>
/// Rotates about the origin. Returns a new matrix with the result.
/// </summary>
/// <param name="degrees">The degrees to rotate.</param>
/// <param name="clockwise">If False, then + degrees rotates counter clockwise.
/// If True, then + degrees rotates clockwise. Of course, if the sign of the degrees
/// is -, then the rotation will be opposite whatever the + direction is.</param>
public Transform2D Rotate(decimal degrees, bool clockwise = false)
{
var r = new Transform2D();
var theta = DecimalEx.ToRad(degrees);
if (clockwise)
{
theta *= -1;
}
// 0 1 2
// 0 cos -sin 0
// 1 sin cos 0
// 2 0 0 1
r[0, 0] = DecimalEx.Cos(theta);
r[0, 1] = -DecimalEx.Sin(theta);
r[1, 0] = DecimalEx.Sin(theta);
r[1, 1] = DecimalEx.Cos(theta);
return(r.Multiply(this));
}