program essai
  use usegenplot
  implicit none

  integer                   :: foo, bar
  integer                   :: nbarg
  integer                   :: numframe = 0
  character(len=256)        :: arg

  ! write(0, *)   "------------ essai graf anim ---------------"

  nbarg = IARGC()
  if (nbarg .GT. 0) then
       call GETARG(1, arg)
       ! write (0, '(A40, A5)') "argument = ",  arg
       read (arg, *) numframe
  endif

  write(0, '(A20, I5)')  "frame number =", numframe

  call init_genplot("essai.genplot")
  call do_frame(7)

  call gplt_setcol(2)

  bar = (numframe * 20) - 120
  do foo=20, 620, 50
    call gplt_line(foo, 20, bar, 460)
    call gplt_line(bar, 20, foo, 460)
  enddo

  call end_genplot("done for today")

contains        !------------------------------------------

subroutine do_frame(color)
  integer, intent(in)           :: color
  integer                       :: savecol

  savecol = gplt_getcol()
  call gplt_setcol(color)
  call gplt_rect(0, 0, 640, 480)
  call gplt_setcol(savecol)

end subroutine

end program