class Sprite
  def bmp(arg1, arg2 = nil)
	if arg2
	  arg1 = Graphics.width if arg1 == -1
	  arg2 = Graphics.height if arg2 == -1
	  self.bitmap = Bitmap.new(arg1, arg2)
	elsif arg1.is_a?(String)
	  self.bitmap = BitmapCache.load_bitmap(arg1)
	end
  end

  def xyz=(value)
	self.x = value[0] || 0
	self.y = value[1] || 0
	self.z = value[2] || 0
  end

  def resetBitmap(font = "System")
	self.bitmap.clear if self.bitmap
	self.bmp(-1,-1)
	eval("pbSet#{font}Font(self.bitmap)")
  end
end

Example:
mySprite = Sprite.new(@viewport)   # Create a Sprite object
mySprite.bmp(-1,-1)	# Assign an empty bitmap equal to the screen width and height to the sprite
mySprite.xyz = [100, 33]	# Set x to 100 and y to 33. Z stays where it was; zero in this case.
mySprite.xyz = [82,0,9]	# Set x to 82, set y to 0, set z to 9.
mySprite.resetBitmap   # Clears any text and any images that were on the bitmap and re-assigns an empty bitmap to the sprite.