text: #!/usr/bin/env python3
  
  # Requires Python 3.2+ (or Python 2.7), the Python Pillow package,
  # and nona (from Hugin)
  
  # generate.py - A multires tile set generator for Pannellum
  # Copyright (c) 2014-2018 Matthew Petroff
  #
  # Permission is hereby granted, free of charge, to any person obtaining a copy
  # of this software and associated documentation files (the "Software"), to deal
  # in the Software without restriction, including without limitation the rights
  # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  # copies of the Software, and to permit persons to whom the Software is
  # furnished to do so, subject to the following conditions:
  #
  # The above copyright notice and this permission notice shall be included in
  # all copies or substantial portions of the Software.
  #
  # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  # THE SOFTWARE.
  
  from __future__ import print_function
  
  import argparse
  from PIL import Image
  import os
  import sys
  import math
  from distutils.spawn import find_executable
  import subprocess
  
  # Find external programs
  try:
      nona = find_executable('nona')
  except KeyError:
      # Handle case of PATH not being set
      nona = None
  
  # Parse input
  parser = argparse.ArgumentParser(description='Generate a Pannellum multires tile set from an full equirectangular panorama.',
                                   formatter_class=argparse.ArgumentDefaultsHelpFormatter)
  parser.add_argument('inputFile', metavar='INPUT',
                      help='full equirectangular panorama to be processed')
  parser.add_argument('-o', '--output', dest='output', default='./output',
                      help='output directory')
  parser.add_argument('-s', '--tilesize', dest='tileSize', default=512, type=int,
                      help='tile size in pixels')
  parser.add_argument('-c', '--cubesize', dest='cubeSize', default=0, type=int,
                      help='cube size in pixels, or 0 to retain all details')
  parser.add_argument('-q', '--quality', dest='quality', default=75, type=int,
                      help='output JPEG quality 0-100')
  parser.add_argument('--png', action='store_true',
                      help='output PNG tiles instead of JPEG tiles')
  parser.add_argument('-n', '--nona', default=nona, required=nona is None,
                      metavar='EXECUTABLE',
                      help='location of the nona executable to use')
  args = parser.parse_args()
  
  # Process input image information
  print('Processing input image information...')
  origWidth, origHeight = Image.open(args.inputFile).size
  if float(origWidth) / origHeight != 2:
      print('Error: the image width is not twice the image height.')
      print('Input image must be a full, not partial, equirectangular panorama!')
      sys.exit(1)
  if args.cubeSize != 0:
      cubeSize = args.cubeSize
  else:
      cubeSize = 8 * int(origWidth / math.pi / 8)
  levels = int(math.ceil(math.log(float(cubeSize) / args.tileSize, 2))) + 1
  origHeight = str(origHeight)
  origWidth = str(origWidth)
  origFilename = os.path.join(os.getcwd(), args.inputFile)
  extension = '.jpg'
  if args.png:
      extension = '.png'
  
  # Create output directory
  os.makedirs(args.output)
  
  # Generate PTO file for nona to generate cube faces
  # Face order: front, back, up, down, left, right
  faceLetters = ['f', 'b', 'u', 'd', 'l', 'r']
  text = []
  text.append('p E0 R0 f0 h' + str(cubeSize) + ' n"TIFF_m" u0 v90 w' + str(cubeSize))
  text.append('m g1 i0 m2 p0.00784314')
  text.append('i a0 b0 c0 d0 e0 f4 h' + origHeight + ' n"' + origFilename + '" p0 r0 v360 w' + origWidth + ' y0')
  text.append('i a0 b0 c0 d0 e0 f4 h' + origHeight + ' n"' + origFilename + '" p0 r0 v360 w' + origWidth + ' y180')
  text.append('i a0 b0 c0 d0 e0 f4 h' + origHeight + ' n"' + origFilename + '" p-90 r0 v360 w' + origWidth + ' y0')
  text.append('i a0 b0 c0 d0 e0 f4 h' + origHeight + ' n"' + origFilename + '" p90 r0 v360 w' + origWidth + ' y0')
  text.append('i a0 b0 c0 d0 e0 f4 h' + origHeight + ' n"' + origFilename + '" p0 r0 v360 w' + origWidth + ' y90')
  text.append('i a0 b0 c0 d0 e0 f4 h' + origHeight + ' n"' + origFilename + '" p0 r0 v360 w' + origWidth + ' y-90')
  text.append('v')
  text.append('*')
  text = '\n'.join(text)
  with open(os.path.join(args.output, 'cubic.pto'), 'w') as f:
      f.write(text)
  
  # Create cube faces
  print('Generating cube faces...')
  subprocess.check_call([args.nona, '-o', os.path.join(args.output, 'face'), os.path.join(args.output, 'cubic.pto')])
  faces = ['face0000.tif', 'face0001.tif', 'face0002.tif', 'face0003.tif', 'face0004.tif', 'face0005.tif']
  
  # Generate tiles
  print('Generating tiles...')
  for f in range(0, 6):
      size = cubeSize
      face = Image.open(os.path.join(args.output, faces[f]))
      if 'A' in face.mode:
          if face.mode == 'RGBA':
              face = face.convert('RGB')
          elif face.mode == 'LA':
              face = face.convert('L')
      for level in range(levels, 0, -1):
          if not os.path.exists(os.path.join(args.output, str(level))):
              os.makedirs(os.path.join(args.output, str(level)))
          tiles = int(math.ceil(float(size) / args.tileSize))
          if (level < levels):
              face = face.resize([size, size], Image.ANTIALIAS)
          for i in range(0, tiles):
              for j in range(0, tiles):
                  left = j * args.tileSize
                  upper = i * args.tileSize
                  right = min(j * args.tileSize + args.tileSize, size)
                  lower = min(i * args.tileSize + args.tileSize, size)
                  tile = face.crop([left, upper, right, lower])
                  tile.load()
                  tile.save(os.path.join(args.output, str(level), faceLetters[f] + str(i) + '_' + str(j) + extension), quality = args.quality)
          size = int(size / 2)
  
  # Generate fallback tiles
  print('Generating fallback tiles...')
  for f in range(0, 6):
      if not os.path.exists(os.path.join(args.output, 'fallback')):
          os.makedirs(os.path.join(args.output, 'fallback'))
      face = Image.open(os.path.join(args.output, faces[f]))
      if 'A' in face.mode:
          if face.mode == 'RGBA':
              face = face.convert('RGB')
          elif face.mode == 'LA':
              face = face.convert('L')
      face = face.resize([1024, 1024], Image.ANTIALIAS)
      face.save(os.path.join(args.output, 'fallback', faceLetters[f] + extension), quality = args.quality)
  
  # Clean up temporary files
  os.remove(os.path.join(args.output, 'cubic.pto'))
  for face in faces:
      os.remove(os.path.join(args.output, face))
  
  # Generate config file
  text = []
  text.append('{')
  text.append('    "type": "multires",')
  text.append('    ')
  text.append('    "multiRes": {')
  text.append('        "path": "/%l/%s%y_%x",')
  text.append('        "fallbackPath": "/fallback/%s",')
  text.append('        "extension": "' + extension[1:] + '",')
  text.append('        "tileResolution": ' + str(args.tileSize) + ',')
  text.append('        "maxLevel": ' + str(levels) + ',')
  text.append('        "cubeResolution": ' + str(cubeSize))
  text.append('    }')
  text.append('}')
  text = '\n'.join(text)
  with open(os.path.join(args.output, 'config.json'), 'w') as f:
      f.write(text)
  