snake.py

import pygame,random
pygame.init()
gameDisplay= pygame.display.set_mode((800,600))
surface = pygame.Surface(gameDisplay.get_size())
surface = surface.convert()
surface.fill((255,255,255))
gameDisplay.blit(surface,(0,0))
pygame.display.set_caption('Snake')
clock = pygame.time.Clock()

RECTANGLE_SIZE = 10
FPS = 24
UP = [0,-1]
DOWN = [0,1]
LEFT = [-1,0]
RIGHT = [1,0]

class Snake():
    def __init__(self):
        self.positions = [[400,200]]
        self.lastMove = random.choice([UP,DOWN,LEFT,RIGHT])
        self.length = 1

    def setDirection(self,direction):
        if len(self.positions) > 1 and [direction[0] * -1, direction[1] * -1] == self.lastMove:
            return
        else:
            self.lastMove = direction

    def move(self):
        head = self.positions[0]
        newHead = [(head[0] + self.lastMove[0]*RECTANGLE_SIZE) % 800, (head[1] + self.lastMove[1]*RECTANGLE_SIZE) % 600]

        if len(self.positions) > 2 and newHead in self.positions[2:]:
            self.gameOver()
        elif newHead[0] in [0,800] or newHead[1] in [0,600]:
            self.gameOver()
        else:
            self.positions.insert(0,newHead)
            if len(self.positions) > self.length:
                self.positions.pop()


    def draw(self,surface):
        for position in self.positions:
            rectangle = pygame.Rect((position[0], position[1]), (RECTANGLE_SIZE, RECTANGLE_SIZE))
            pygame.draw.rect(surface, (0,0,0), rectangle)


    def gameOver(self):
        self.positions = [[400,200]]
        self.lastMove = random.choice([UP,DOWN,LEFT,RIGHT])
        self.length = 1

class Food():
    def __init__(self):
        position_x = random.randint(1,(800/RECTANGLE_SIZE)-1) * RECTANGLE_SIZE
        position_y = random.randint(1,(600/RECTANGLE_SIZE)-1) * RECTANGLE_SIZE
        self.position = [position_x,position_y]

    def newPosition(self):
        position_x = random.randint(1,(800/RECTANGLE_SIZE)-1) * RECTANGLE_SIZE
        position_y = random.randint(1,(600/RECTANGLE_SIZE)-1) * RECTANGLE_SIZE
        self.position = [position_x,position_y]

    def draw(self,surface):
        rectangle = pygame.Rect((self.position[0], self.position[1]), (RECTANGLE_SIZE, RECTANGLE_SIZE))
        pygame.draw.rect(surface, (255,0,0), rectangle)

    def hasBeenEaten(self, snake):
        if self.position == snake.positions[0]:
            snake.length += 1
            self.newPosition()

snake = Snake()
food = Food()
running = True
while running:

    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False
        elif event.type == pygame.KEYDOWN:
            if event.key == pygame.K_UP:
                snake.setDirection(UP)
            elif event.key == pygame.K_DOWN:
                snake.setDirection(DOWN)
            elif event.key == pygame.K_LEFT:
                snake.setDirection(LEFT)
            elif event.key == pygame.K_RIGHT:
                snake.setDirection(RIGHT)

    surface.fill((255,255,255))
    snake.move()
    food.hasBeenEaten(snake)
    snake.draw(surface)
    food.draw(surface)
    pygame.display.update()
    gameDisplay.blit(surface, (0,0))
    clock.tick(FPS)

pygame.quit()