python: snake game

Here is my second try to write a simple game in python using pygame. I'm not posting here the whole source code since I don't want the post to be too long. The complete source code can be downloaded from this link.

First lets take a look at the game...

Snake Game Screen Cast:

 

Snake Class: 

Besides pygame, im using three self made classes on the game:

• snake.py
• food.py 
• colors.py

The source code has plenty of comments which should make it quite easy to understand what is going on.

  1 #==============================================================================================#
  2 # Name        : snake.py                                                                       #
  3 # Description : The snake class definition for the snake game.                                 #
  4 # Author      : Adrian Antonana                                                                #
  5 # Date        : 29.07.2012                                                                     #
  6 #==============================================================================================#
  7 
  8 # imports
  9 import pygame as pg
 10 from colors import *
 11 
 12 # motion direction constants
 13 UP    = 0
 14 DOWN  = 1
 15 LEFT  = 2
 16 RIGHT = 3
 17 
 18 # block sizes
 19 BLOCK_SIZE       = 30
 20 BLOCK_SIZE_INNER = 20
 21 
 22 # snake class definition
 23 class snake:
 24 
 25   # constructor
 26   def __init__(self,surface,headposx=10,headposy=10):
 27     self.surface = surface
 28     self.length  = 10
 29     self.poslist = [(headposx,y) for y in reversed(range(headposy-self.length+1,headposy+1))]
 30     self.motdir  = RIGHT
 31     self.crashed = False
 32 
 33     # for drawing the snake
 34     self.snakeblock = pg.Surface((BLOCK_SIZE,BLOCK_SIZE))
 35     self.snakeblock.set_alpha(255)
 36     self.snakeblock.fill(GREEN)
 37     self.snakeblockdark = pg.Surface((BLOCK_SIZE_INNER,BLOCK_SIZE_INNER))
 38     self.snakeblockdark.set_alpha(255)
 39     self.snakeblockdark.fill(GREEN_DARK)
 40 
 41     # for removing the snake
 42     self.backblock = pg.Surface((BLOCK_SIZE,BLOCK_SIZE))
 43     self.backblock.set_alpha(255)
 44     self.backblock.fill(BLACK)
 45 
 46   # get snake's head position
 47   def getHeadPos(self):
 48     return (self.poslist[0])
 49 
 50   # get the motion direction
 51   def getMotionDir(self):
 52     return self.motdir
 53 
 54   # get the snake positions list
 55   def getPosList(self):
 56     return self.poslist
 57 
 58   # set the motion direction
 59   def setMotionDir(self,motdir):
 60     self.motdir = motdir
 61 
 62   # increase the snake length by one
 63   def incLength(self):
 64     self.length += 1
 65 
 66   # move the snake updates the positions list and checks if the snake has crashed
 67   def move(self):
 68     motdir = self.getMotionDir()
 69     headpos = self.getHeadPos()
 70 
 71     # update positions
 72     if motdir == UP:
 73       poslist = [(headpos[0]-1,headpos[1])]
 74     elif motdir == DOWN:
 75       poslist = [(headpos[0]+1,headpos[1])]
 76     elif motdir == LEFT:
 77       poslist = [(headpos[0],headpos[1]-1)]
 78     elif motdir == RIGHT:
 79       poslist = [(headpos[0],headpos[1]+1)]
 80 
 81     poslist.extend(self.poslist[:-1])
 82     self.poslist = poslist
 83 
 84     # check if crashed
 85     if self.getHeadPos() in self.getPosList()[1:]:
 86       self.crashed = True
 87 
 88   # check if the snake has crashed
 89   def chrashed(self):
 90     return self.crashed
 91 
 92   # grow the snake. add a new position at the end
 93   def grow(self):
 94     lastpos = self.getPosList()[-1]
 95     self.length += 1
 96     self.poslist.append((lastpos[0]-1,lastpos[1]))
 97 
 98   # draw the snake
 99   def draw(self):
100     skb = self.snakeblock
101     skbd = self.snakeblockdark
102     sf = self.surface
103 
104     for blockpos in self.getPosList():
105       sf.blit(skb,(blockpos[1]*BLOCK_SIZE,blockpos[0]*BLOCK_SIZE))
106       sf.blit(skbd,(blockpos[1]*BLOCK_SIZE+5,blockpos[0]*BLOCK_SIZE+5))
107 
108   # delete the snake
109   def remove(self):
110     bkb = self.backblock
111     sf = self.surface
112 
113     # draw block for every snake position
114     for blockpos in self.getPosList():
115       sf.blit(bkb,(blockpos[1]*BLOCK_SIZE,blockpos[0]*BLOCK_SIZE))