make_test_MRC.lua

header_fmt =               'iii'                 -- nx, ny, nz
header_fmt = header_fmt .. 'i'                   -- mode
header_fmt = header_fmt .. 'iii'                 -- nxstart, nystart, nzstart
header_fmt = header_fmt .. 'iii'                 -- mx, my, mz
header_fmt = header_fmt .. 'fff'                 -- xlen, ylen, zlen
header_fmt = header_fmt .. 'fff'                 -- alpha, beta, gamma
header_fmt = header_fmt .. 'iii'                 -- mapc, mapr, maps
header_fmt = header_fmt .. 'fff'                 -- amin, amax, amean
header_fmt = header_fmt .. 'i'                   -- ispg
header_fmt = header_fmt .. 'i'                   -- Next
header_fmt = header_fmt .. 'h'                   -- CreateID
header_fmt = header_fmt .. 'hiiiiiii'            -- Empty
header_fmt = header_fmt .. 'h'                   -- nint
header_fmt = header_fmt .. 'h'                   -- nreal
header_fmt = header_fmt .. 'iiiii'               -- Empty
header_fmt = header_fmt .. 'ii'                  -- imodStamp, imodFlags
header_fmt = header_fmt .. 'h'                   -- idType
header_fmt = header_fmt .. 'h'                   -- lens
header_fmt = header_fmt .. 'hh'                  -- nd1, nd2
header_fmt = header_fmt .. 'hh'                  -- vd1, vd2
header_fmt = header_fmt .. 'ffffff'              -- tiltAngles
header_fmt = header_fmt .. 'fff'                 -- xorg, yorg, zorg
header_fmt = header_fmt .. 'c4'                  -- MAP 
header_fmt = header_fmt .. 'c4'                  -- DA  
header_fmt = header_fmt .. 'f'                   -- RMS
header_fmt = header_fmt .. 'i'                   -- nlabl
header_fmt = header_fmt .. string.rep('c80', 10) -- labels

int_size = arg[1]
flt_size = int_size^1
int_vol  = int_size * int_size * int_size -- exponentiation converts to float
flt_vol  = flt_size^3

nx, ny, nz = int_size, int_size, int_size
mode = 0
nxstart, nystart, nzstart = 0, 0, 0
mx, my, mz = int_size, int_size, int_size
xlen, ylen, zlen = flt_size, flt_size, flt_size
alpha, beta, gamma = 90.0, 90.0, 90.0
mapc, mapr, maps = 1, 2, 3
amin, amax, amean = 0.0, 255.0, 255.0 / flt_vol
ispg = 0
Next = 0
CreateID = 0
nint = 0
nreal = 32
imodStamp = 1146047817
imodFlags = 0
idType = 0
lens = 0
nd1, nd2 = 0, 0
vd1, vd2 = 0, 0
ta1, ta2, ta3, ta4, ta5, ta6 = 0.0, 0.0, 0.0, 0.0, 0.0, 0.0
xorg, yorg, zorg = 0.0, 0.0, 0.0
map = 'MAP '
da = 'DA  '
rms = math.sqrt(255^2 / flt_vol)
nlabl = 0
label = string.rep(' ', 80)

header = string.pack(header_fmt, nx, ny, nz, mode, nxstart, nystart, nzstart,
                     mx, my, mz, xlen, ylen, zlen, alpha, beta, gamma, mapc,
                     mapr, maps, amin, amax, amean, ispg, Next, CreateID,
                     0, 0, 0, 0, 0, 0, 0, 0, nint, nreal, 0, 0, 0, 0, 0,
                     imodStamp, imodFlags, idType, lens, nd1, nd2, vd1, vd2,
                     ta1, ta2, ta3, ta4, ta5, ta6, xorg, yorg, zorg, map, da,
                     rms, nlabl, label, label, label, label, label, label,
                     label, label, label, label)
                     
MRC = io.open(arg[3], 'wb')
MRC:write(header)

for k = 1, int_size do -- Z maps
  for j = 1, int_size do -- Y mapr
    for i = 1, int_size do -- X mapc
      index = ((k - 1) * int_size * int_size) + ((j - 1) * int_size) + i
      if index == tonumber(arg[2]) then
        print('Writing the one white pixel to ' .. i .. ', ' .. j .. ', ' ..
              k .. '!')
        MRC:write(string.pack('B', 255))
      else
        MRC:write(string.pack('B', 0))
      end
    end
  end
end

MRC:close()