pro mf_01 ; Nomenclature: 'mf' = multiple files
    
    ; Bo Milvang-Jensen (milvang@astro.ku.dk)
    ; For the RelViz Web exhibition, June 1996
    ; Last rev.: 07-Jun-1996

    ; Make multiple Inventor files with 1 ray in each

    ; We vary: a_over_M: 0 -> 1.00 in 101 steps

    ; Ray directly towards the center, in the equatorial plane


    nfiles = 101
    basename = '/m/RelViz/WWW/milvang/Anim/01/a'
    extension = '.iv'

    ; =========================== Start and end values =========================
    ; Black hole properties
    M1        = 1.0   & M2        = 1.0
    a_over_M1 = 0.0   & a_over_M2 = 1.00

    ; Initial position of photon
    r1        = 5.0   & r2        = 5.0
    th1       = !pi/2 & th2       = !pi/2
    ph1       = !pi/4 & ph2       = !pi/4
    t1        = 0.0   & t2        = 0.0

    ; Initial direction of photon
    dr1       = -0.5  & dr2       = -0.5
    dth1      =  0.0  & dth2      =  0.0
    dph1      =  0.0  & dph2      =  0.0

    ; Affine parameter control
    dl = 0.2
    nl = 300

    ; 3D scene format
    scene_format = 'Inventor'

    ; Drawing style of geodesic
    pointset = 0 ; 1 means Line

    ; Color of geodesic
    cr1       = 0.0   & cr2       = 0.0
    cg1       = 1.0   & cg2       = 1.0
    cb1       = 1.0   & cb2       = 1.0

    ; Coordinate system widget
    coo = 'on'
    coo_length = 5.0

    ; Horizon widget
    horizon = 'on'
    auto_radius = 'on'
    manual_radius = 1.0 ; Only used if auto_radius = 'off'
    hcr1      = 1.0   & hcr2      = 1.0
    hcg1      = 1.0   & hcg2      = 1.0
    hcb1      = 0.0   & hcb2      = 0.0
    transp1   = 0.50  & transp2   = 0.50

    ; Static Limit / Ergosphere widget
    make_r_stat = 'on'
    scr1      = 1.0   & scr2      = 1.0
    scg1      = 0.0   & scg2      = 0.0
    scb1      = 1.0   & scb2      = 1.0
    ; ==========================================================================

    ; The rest
    append = 0 ; 0 means do not append
    verbose = 0 ; 0 means not verbose

    for i=0,nfiles-1 do begin ; ----------------- Loop -------------------------
      ; Calculate parameters for step i:
      ;
      q = (nfiles-1)
  
      ; Black hole properties
      M = M1 + i*(M2-M1)/q
      a_over_M = a_over_M1 + i*(a_over_M2-a_over_M1)/q
  
      ; Initial position of photon
      r = r1 + i*(r2-r1)/q
      th = th1 + i*(th2-th1)/q
      ph = ph1 + i*(ph2-ph1)/q
      t = t1 + i*(t2-t1)/q
  
      ; Initial direction of photon
      dr = dr1 + i*(dr2-dr1)/q
      dth = dth1 + i*(dth2-dth1)/q
      dph = dph1 + i*(dph2-dph1)/q
  
      ; Affine parameter control
      ; nothing
  
      ; 3D scene format
      ; nothing
  
      ; Drawing style of geodesic
      ; nothing
  
      ; Color of geodesic
      cr = cr1 + i*(cr2-cr1)/q
      cg = cg1 + i*(cg2-cg1)/q
      cb = cb1 + i*(cb2-cb1)/q
  
      ; Coordinate system widget
      ; nothing
  
      ; Horizon widget
      ; ...
      hcr = hcr1 + i*(hcr2-hcr1)/q
      hcg = hcg1 + i*(hcg2-hcg1)/q
      hcb = hcb1 + i*(hcb2-hcb1)/q
      transp = transp1 + i*(transp2-transp1)/q
  
      ; Static Limit / Ergosphere widget
      ; ...
      scr = scr1 + i*(scr2-scr1)/q
      scg = scg1 + i*(scg2-scg1)/q
      scb = scb1 + i*(scb2-scb1)/q
  
      ; The rest
      ; ...
      out_file = basename+padzero3(i)+extension ; Set output file name
  
      script1, M, a_over_M, r, th, ph, t, dr, dth, dph, dl, nl, $
  	     scene_format, pointset, cr, cg, cb, coo, coo_length, $
  	     horizon, auto_radius, manual_radius, $
  	     hcr, hcg, hcb, transp, make_r_stat, scr, scg, scb, $
  	     out_file, append=append, verbose=verbose
    end ; ----------------------------------------------------------------------

end