def affine(sx, rx, ry, sy, tx, ty)
      primitive 'affine ' + format('%g,%g,%g,%g,%g,%g', sx, rx, ry, sy, tx, ty)
    end
def affine(sx, rx, ry, sy, tx, ty)
      primitive 'affine ' + format('%g,%g,%g,%g,%g,%g', sx, rx, ry, sy, tx, ty)
    end
Apply coordinate transformations to support scaling (s), rotation (r),
 and translation (t). Angles are specified in radians.