startshape foo
CF::Time = [time 45 405]
CF::Size = [s 1]
shape foo {
  SQUARE[r (ftime() - 45) 
         s (sqrt(0.5)/max(sin(ftime()),
                  sin(ftime() + 90),
                  sin(ftime() + 180),
                  sin(ftime() + 270)))
         time 0 405]
}

