def _setup_cam(camera):
  """Generates a -camera input string for GAPS viewers."""
  if camera == 'fixed':
    init_camera = ('1.0451 1.17901 0.630437 '
                   '-0.614259 -0.695319 -0.373119 '
                   '-0.547037 0.715996 -0.433705')
  elif camera == 'default':
    init_camera = None
  else:
    init_camera = camera
  if init_camera is not None:
    init_camera = ' -camera %s' % init_camera
  else:
    init_camera = ''
  return init_camera