snake.py

import pygame, sys, random

SCREEN_WIDTH = 480
SCREEN_HEIGHT = 480
GRIDSIZE = 20
GRID_WIDTH = SCREEN_HEIGHT / GRIDSIZE
GRID_HEIGHT = SCREEN_WIDTH / GRIDSIZE
UP = (0,-1)
DOWN = (0,1)
LEFT = (-1,0)
RIGHT = (1,0)

 
class Snake():
	def __init__(self):
		self.length = 1
		self.positions = [((SCREEN_WIDTH / 2),(SCREEN_HEIGHT / 2))]
		self.direction = random.choice([UP, DOWN, LEFT, RIGHT])
		self.colour = (12,24,47)
		self.score = 0 

	def get_head_position(self):
		return self.positions[0]

	def turn(self, point):
		if self.length > 1 and (point[0] * -1, point[1] * -1) == self.direction:
			return
		else:
			self.direction = point

	def move(self):
		cur = self.get_head_position()
		x,y = self.direction
		new = (((cur[0] + (x*GRIDSIZE)) % SCREEN_WIDTH), (cur[1] + (y*GRIDSIZE)) % SCREEN_HEIGHT)
		if len(self.positions) > 2 and new in self.positions[2:]:
			self.reset()
		else:
			self.positions.insert(0, new)
			if len(self.positions) > self.length:
				self.positions.pop()

	def reset(self):
		self.length = 1
		self.positions = [((SCREEN_WIDTH / 2), (SCREEN_HEIGHT / 2))]
		self.direction = random.choice([UP, DOWN, LEFT, RIGHT])
		self.score = 0

	def draw(self, surface):
		for p in self.positions:
			r = pygame.Rect((p[0], p[1]), (GRIDSIZE, GRIDSIZE))
			pygame.draw.rect(surface, self.colour, r)
			pygame.draw.rect(surface, (93,216,228), r, 1)

	def handle_keys(self):
		for event in pygame.event.get():
			if event.type == pygame.QUIT:
				pygame.quit()
				sys.exit()
			elif event.type == pygame.KEYDOWN:
				if event.key == pygame.K_UP:
					self.turn(UP)
				elif event.key == pygame.K_DOWN:
					self.turn(DOWN)
				elif event.key == pygame.K_LEFT:
					self.turn(LEFT)
				elif event.key == pygame.K_RIGHT:
					self.turn(RIGHT)

class Food():
	def __init__(self):
		self.position = (0,0)
		self.colour = (223,163,49)
		self.randomise_position()
	
	def randomise_position(self):
		self.position = (random.randint(0, GRID_WIDTH-1)*GRIDSIZE, random.randint(0, GRID_HEIGHT-1)*GRIDSIZE)

	def draw(self, surface):
		r = pygame.Rect((self.position[0], self.position[1]), (GRIDSIZE, GRIDSIZE))
		pygame.draw.rect(surface, self.colour, r) 
		pygame.draw.rect(surface, (93, 216, 228), r, 1)

def drawGrid(surface):
	for y in range(0, int(GRID_HEIGHT)):
		for x in range(0, int(GRID_WIDTH)):
			if (x+y)%2 == 0:
				r = pygame.Rect((x*GRIDSIZE, y*GRIDSIZE), (GRIDSIZE, GRIDSIZE))
				pygame.draw.rect(surface, (92,216,228), r)
			else:
				rr = pygame.Rect((x*GRIDSIZE, y*GRIDSIZE), (GRIDSIZE, GRIDSIZE))
				pygame.draw.rect(surface, (84,194,205), rr)

def main():
	pygame.init()

	snake = Snake()
	food = Food()

	clock= pygame.time.Clock()
	screen = pygame.display.set_mode((SCREEN_WIDTH, SCREEN_HEIGHT), 0, 32)
	caption = pygame.display.set_caption('snake')
	surface = pygame.Surface(screen.get_size())
	surface = surface.convert()
	drawGrid(surface)

	myfont = pygame.font.SysFont("monospace", 16)

	while (True):
		clock.tick(10)
		snake.handle_keys()
		drawGrid(surface)
		snake.move()
		if snake.get_head_position() == food.position:
			snake.length += 1
			snake.score += 1
			food.randomise_position()
		snake.draw(surface)
		food.draw(surface) 

		#handle events 
		screen.blit(surface, (0,0))
		text = myfont.render("Score {0}".format(snake.score),1,(0,0,0))
		screen.blit(text, (5,10))
		pygame.display.update()


main()