snake_game.py

# Contribution by https://github.com/Karan9034

import pygame
import sys
import random

class Snake(object):
	def __init__(self):
		self.length=1
		self.positions=[((SCREEN_WIDTH/2),(SCREEN_HEIGHT/2))]
		self.direction=random.choice([UP,DOWN,LEFT,RIGHT])
		self.color=(17,24,47)

	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:]:
			pygame.quit()
			sys.exit()
		else:
			self.positions.insert(0,new)
			if len(self.positions)>self.length:
				self.positions.pop()

	def draw(self,surface):
		for p in self.positions:
			r=pygame.Rect((p[0],p[1]),(GRIDSIZE,GRIDSIZE))
			pygame.draw.rect(surface,self.color,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)
				elif event.key==pygame.K_ESCAPE:
					pygame.quit()
					sys.exit()

class Food(object):
	def __init__(self):
		self.position=(0,0)
		self.color=(233,163,49)
		self.randomize_position()

	def randomize_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.color,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,(200,200,200),r)
			else:
				rr=pygame.Rect((x*GRIDSIZE,y*GRIDSIZE),(GRIDSIZE,GRIDSIZE))
				pygame.draw.rect(surface,(100,100,100),rr)

SCREEN_WIDTH=480
SCREEN_HEIGHT=480

GRIDSIZE=20
GRID_WIDTH=SCREEN_WIDTH/GRIDSIZE
GRID_HEIGHT=SCREEN_HEIGHT/GRIDSIZE

UP=(0,-1)
DOWN=(0,1)
LEFT=(-1,0)
RIGHT=(1,0)

def main():
	pygame.init()

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

	snake=Snake()
	food= Food()

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

	score=0
	while True:
		clock.tick(10)
		snake.handle_keys()
		drawGrid(surface)
		snake.move()
		if snake.get_head_position()==food.position:
			snake.length+=1
			score+=1
			food.randomize_position()
		snake.draw(surface)
		food.draw(surface)
		screen.blit(surface,(0,0))
		text=myfont.render("Score: {0}".format(score),1,(0,0,0))
		screen.blit(text,(5,10))
		pygame.display.update()

if __name__=="__main__":
	main()