undef("set_cn_resources")
function set_cn_resources (data[*][*]:numeric, res:logical)

begin

  opts = res

; The ContourParameters resource can either be a scalar that
; represents the contour level spacing, or it can be an array
; of three elements that represent the minimum level, the maximum
; level, and the level spacing.
;
  mx = max(data)
  mn = min(data)

  if(mn.ne.mx.and.opts.and.isatt(opts,"ContourParameters")) then
    if(dimsizes(opts@ContourParameters) .eq. 1) then

; Only the contour interval is specified.
      nlev   = tointeger((mx-mn)/opts@ContourParameters)+1
      levels = nice_mnmxintvl(mn,mx,nlev,True)
      if(levels(0) .lt. 0.) then
        ; Set a zero contour.
        nlev = tointeger(levels(0)/opts@ContourParameters) - 1
        levels(0) = nlev*opts@ContourParameters
      end if
      nlev = tointeger((levels(1)-levels(0))/opts@ContourParameters)+1
      levels(1) = levels(0) + nlev*opts@ContourParameters
      levels(2) = opts@ContourParameters

; Min level, max level, and level spacing are specified by user.
    else
      if(dimsizes(opts@ContourParameters) .eq. 3) then
        levels = opts@ContourParameters
      else
        print("wrf_contour: Warning: illegal setting for ContourParameters attribute")
      end if
    end if

  end if

; Contour levels
  if(isvar("levels")) then
    opts@cnLevelSelectionMode = get_res_value_keep(opts, "cnLevelSelectionMode", "ManualLevels")
    opts@cnMinLevelValF       = get_res_value_keep(opts, "cnMinLevelValF", levels(0))
    opts@cnMaxLevelValF       = get_res_value_keep(opts, "cnMaxLevelValF", levels(1))
    opts@cnLevelSpacingF      = get_res_value_keep(opts, "cnLevelSpacingF",levels(2))
    delete(levels)
  end if


; Set the default zero line thickness to 2, and the negative contour
; line dash pattern to 1 (0 is solid).
  opts@gsnContourZeroLineThicknessF = get_res_value_keep(opts, "gsnContourZeroLineThicknessF",2.0)
  opts@gsnContourNegLineDashPattern = get_res_value_keep(opts, "gsnContourNegLineDashPattern",1)


; Set resources that apply for both filled and line contour plots.
  opts@cnFillDrawOrder            = get_res_value_keep(opts,"cnFillDrawOrder", "PreDraw")


  opts@cnLineLabelAngleF          = get_res_value_keep(opts,"cnLineLabelAngleF", 0.0)
  opts@cnLineLabelFontHeightF     = get_res_value_keep(opts,"cnLineLabelFontHeightF", 0.015)
  opts@cnInfoLabelFontHeightF     = get_res_value_keep(opts,"cnInfoLabelFontHeightF", 0.015)
  opts@cnLineLabelPerimOn         = get_res_value_keep(opts,"cnLineLabelPerimOn", True)
  opts@cnInfoLabelPerimOn         = get_res_value_keep(opts,"cnInfoLabelPerimOn", False)
  opts@cnLineLabelBackgroundColor = get_res_value_keep(opts,"cnLineLabelBackgroundColor", -1)
  opts@cnHighLabelBackgroundColor = get_res_value_keep(opts,"cnHighLabelBackgroundColor", -1)
  opts@cnLowLabelBackgroundColor  = get_res_value_keep(opts,"cnLowLabelBackgroundColor", -1)
  opts@cnLineColor                = get_res_value_keep(opts,"cnLineColor", "Black")
  opts@cnLineLabelFontColor       = get_res_value_keep(opts,"cnLineLabelFontColor",opts@cnLineColor)
  opts@cnLineLabelPerimColor      = get_res_value_keep(opts,"cnLineLabelPerimColor",opts@cnLineColor)
  opts@cnInfoLabelFontColor       = get_res_value_keep(opts,"cnInfoLabelFontColor",opts@cnLineColor)
  opts@cnHighLabelFontColor       = get_res_value_keep(opts,"cnHighLabelFontColor",opts@cnLineColor)
  opts@cnLowLabelFontColor        = get_res_value_keep(opts,"cnLowLabelFontColor",opts@cnLineColor)

; Set field Title and levels if available
  if(.not.isatt(opts,"cnInfoLabelString")) then
    info_string = " Contours: $CMN$ to $CMX$ by $CIU$"
    if(isatt(opts,"FieldTitle")) then
        opts@cnInfoLabelString = opts@FieldTitle + info_string
    else if(isatt(data,"description")) then
        opts@cnInfoLabelString = data@description + info_string
    else
        opts@cnInfoLabelString = info_string
    end if
    end if
  end if


  return(opts)
end