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Engineering LibreTexts

7.4: The Setup Code

  • Page ID
    13600
  • # Wormy (a Nibbles clone)
    # By Al Sweigart al@inventwithpython.com
    # http://inventwithpython.com/pygame
    # Released under a "Simplified BSD" license
    
    import random, pygame, sys
    from pygame.locals import *
    
    FPS = 15
    WINDOWWIDTH = 640
    WINDOWHEIGHT = 480
    CELLSIZE = 20
    assert WINDOWWIDTH % CELLSIZE == 0, "Window width must be a multiple of cell size."
    assert WINDOWHEIGHT % CELLSIZE == 0, "Window height must be a multiple of cell size."
    CELLWIDTH = int(WINDOWWIDTH / CELLSIZE)
    CELLHEIGHT = int(WINDOWHEIGHT / CELLSIZE)
    
    #             R    G    B
    WHITE     = (255, 255, 255)
    BLACK     = (  0,   0,   0)
    RED       = (255,   0,   0)
    GREEN     = (  0, 255,   0)
    DARKGREEN = (  0, 155,   0)
    DARKGRAY  = ( 40,  40,  40)
    BGCOLOR = BLACK
    
    UP = 'up'
    DOWN = 'down'
    LEFT = 'left'
    RIGHT = 'right'
    
    HEAD = 0 # syntactic sugar: index of the worm's head
    

    The code at the start of the program just sets up some constant variables used in the game. The width and height of the cells are stored in CELLSIZE. The assert statements on lines 13 and 14 ensure that the cells fit perfectly in the window. For example, if the CELLSIZE was 10 and the WINDOWWIDTH or WINDOWHEIGHT constants were set to 15, then only 1.5 cells could fit. The assert statements make sure that only a whole integer number of cells fits in the window.

    Some more constants are set on lines 19 to 32. The HEAD constant will be explained later in this chapter.