# File lib/as_transform2d.rb, line 28
  def self.rotate(a)
    a = a.to_f.deg2rad
    sin = Math.sin(a)
    cos = Math.cos(a)
    
    AS::Transform2D[
      [cos, -sin, 0, 0],
      [sin,  cos, 0, 0],
      [  0,    0, 1, 0],
      [  0,    0, 0, 1],
    ]
  end