pro construct_cube, data, field_name, MIN=min_data, MAX=max_data, $
                    cube_center=cube_center, cube_length=cube_length, $
                    cube_dimensions=cdims
; constructs cube 
; this is the wrapper around construct_3D_data used to compute
; fractions and do other special data dependent actions 
; returns the data cube
@common_blocks.inc
if N_elements(cdims) eq 0 then cdims = cube_dim

cube_center = slice_ori
cube_center(where(slice_ori  lt 1.e-30)) = $
  [slice_size(0)+0.5*(slice_size(2)-slice_size(0)), $
   slice_size(1)+0.5*(slice_size(3)-slice_size(1))]
cube_length = slice_size(2)-slice_size(0)

if vel.myturn eq 0 then begin
   field_name = list_str[var_index]
   construct_3D_data,   grid_info, cube_center, cube_length, $
                        data_dir, field_name, cdims, data, $
                        interpolate=interpolate_i
;   data = construct_3d_data(FIELDS=field_name, resolution=cdims, interpolation=interpolate_i)
; fudge problems with density and temperature data
; return min and max if requested 
   min_data = min(data, max=max_data)
endif else begin ; return vector field
   ffname = 'velocity'
   names = ['x-velocity', 'y-velocity', 'z-velocity']
   if vector_field_b then begin
      names = ['Bx', 'By', 'Bz']
      ffname = 'B'
   endif
   for i=0,2 do begin
      field_name = names[i]
      construct_3D_data,   grid_info, cube_center, cube_length, $
                           data_dir, field_name, cdims, datatmp, $
                           interpolate=interpolate_i
      s = size(datatmp)
      if i eq 0 then data = fltarr(s[1], s[2], s[3], 3)
      data[*,*,*, i] = datatmp[*,*,*]
   endfor
   field_name = ffname
endelse

center = cube_center
slice_size[[0,1]] = cube_center(where(slice_ori  lt 1.e-30)) - 0.5*cube_length 
slice_size[[2,3]] = cube_center(where(slice_ori  lt 1.e-30)) + 0.5*cube_length
image_stack[0].slice_size = slice_size
update_slice_text, slice_text, slice_size, center, image_stack(0).title, pofi
; common block variables for interactions with SD_vision:
c_center= center
c_length = cube_length

END
; .compile construct_cube