Index

1. PyGame sound

• clearly sound is an integral component of modern games
• sound support in PyGame is pretty good
• PyGame handles different bitrates sound files and will play them correctly
• it also plays sounds in parallel with the game
  • probably by spawning a separate thread

2. Sounds and dictionaries

• these two elements go together quite well
• easy to generate your own library of routines
  • which maintain a dictionary of sound files and
  • gives the programmer the ability to play a sound file when referenced by a string
• this technique was used in penguin tower and it allows dictionary of sound files to be appended
• or reduced or modified (mobile phone version of penguin tower..)
• without causing the client to break

3. Python dictionaries

• python has an inbuilt dictionary type

• #!/usr/bin/python
  
  d = {’spam’:2, ’ham’:1, ’eggs’:10}
  
  print d[’eggs’]

• ./py13.py
  10

4. Dictionary initialisation

• we can create an empty dictionary by:

• d = {}

• we can add to a dictionary by:

• d[’foobar’] = 4

5. Dictionary modification

• we can remove an entry via:

• del d[’eggs’]

• we can test whether an item exists in the dictionary

• #!/usr/bin/python
  
  d = {’spam’:2, ’ham’:1, ’eggs’:10}
  
  if d.has_key(’eggs’):
      print ’we have some eggs’
  else:
      print ’we do not have any eggs’
  
  
  if d.has_key(’flour’):
      print ’we have some flour’
  else:
      print ’we do not have any flour’

6. Library routines necessary to link dictionaries with sound files

• def playSound(sound):
      global soundDict
      if soundDict.has_key(sound):
         soundDict[sound].play()
      else:
         print "no sound file ", sound, " found"

• the programmer calls: playSound("arrowswish")
  • to invoke the appropriate sound file
    

7. Initially all sound files need to be loaded into the dictionary

• soundDict = {}  # define empty dictionary
  
  
  def initSounds():
      addSound("arrowswish")
      addSound("brokenglass")
      addSound("fuse")
      addSound("evillaugh")
      addSound("ohno")
      addSound("ohnoexplode")

8. addSound

• def addSound(name):
      global soundDict
      soundDict[name] = load_sound(name + ".wav")

9. load_sound

• def load_sound(name):
      class NoneSound:
          def play(self):
              pass   # pass means { } in C or Java or C++
      if not pygame.mixer or not pygame.mixer.get_init():
          return NoneSound()
      fullname = getFileName(’sounds’, name)
      try:
          sound = pygame.mixer.Sound(fullname)
      except pygame.error, message:
          print ’cannot load sound file:’, fullname
          return NoneSound()
      return sound

10. Explanation

• define a function load_sound
• define a no-op class NoneSound which has a single method play which does nothing
• then we check whether the pygame sound component is functioning
  • if there is a problem - we return the no-op sound
• otherwise we return the pygame sound object which has been instantiated with the sound file name requested

11. getFileName

• def getFileName(subdir, filename):
      global dataDirectory
  
  
      if dataDirectory == "":
          return os.path.join(subdir, filename)
      else:
          return os.path.join(dataDirectory,
                              os.path.join(subdir, filename))

12. Sound in penguin-tower

• is now implemented in the method above
• could be extended to load a sound file whenever it is needed (rather than at the beginning)
  • what are the pros/cons of this approach?
• currently all sounds are loaded at the beginning and the server requests the client to play a particular sound when it issues the
• pS filename request

13. Penguin Tower Server

• there should be one running on moppsy.comp.glam.ac.uk on port 7000 or 7001 or 7002
• you can download your own executable here
• you should place it into your penguin-tower folder and run it on *86 GNU/Linux platform via:

• chmod 700 penguin-server
  ./penguin-server maps/star

Index

This document was produced using groff-1.19.