main.py

import pygame,time,random

pygame.init()
display_width = 800
display_height = 600

white = (255,255,255)
black = (0,0,0)
red  = (255,0,0)
green  = (0,255,0)

gameDisplay = pygame.display.set_mode((display_width,display_height))
pygame.display.set_caption("Slither")

img = pygame.image.load('head.png')
clock = pygame.time.Clock()

block_size = 20
FPS = 20

direction = "right"

font = pygame.font.SysFont(None,25)
def snake(block_size,snakeList,direction):
	# global direction
	if direction == "right":
		head = pygame.transform.rotate(img,270)

	elif direction == "left":
		head = pygame.transform.rotate(img,90)

	elif direction == "up":
		head = img

	elif direction == "down":
		head = pygame.transform.rotate(img,180)

	gameDisplay.blit(head,(snakeList[-1][0],snakeList[-1][1]))
	for XnY in snakeList[:-1]:
		pygame.draw.rect(gameDisplay,green,[XnY[0],XnY[1],block_size,block_size])

def text_objects(text,color):
	textSurface = font.render(text,True,color)
	return textSurface,textSurface.get_rect()

def message_to_screen(msg,color):
	textSurf, textRect = text_objects(msg,color)
	# screen_text = font.render(msg,True,color)
	# gameDisplay.blit(screen_text,[display_width/2,display_height/2])
	textRect.center = (display_width/2),(display_height/2)
	gameDisplay.blit(textSurf,textRect)

def gameLoop():
	global direction

	gameExit = False
	gameOver = False

	lead_x = display_width/2
	lead_y = display_height/2

	lead_x_change = 20
	lead_y_change = 0

	snakeList = []
	snakeLength = 1

	randAppleX = round(random.randrange(0,display_width-block_size))#/10.0)*10
	randAppleY = round(random.randrange(0,display_height-block_size))#/10.0)*10

	while not gameExit:

		while gameOver:
			gameDisplay.fill(white)
			message_to_screen("Game over press C to play again or Q to quit",red)
			pygame.display.update()

			for event in pygame.event.get():
				if event.type == pygame.QUIT:
					gameOver = False
					gameExit = True
				if event.type == pygame.KEYDOWN:
					if event.key == pygame.K_q:
						gameExit = True
						gameOver = False
					elif event.key == pygame.K_c:
						gameLoop()


		for event in pygame.event.get():
			print event

			if event.type == pygame.QUIT:
				gameExit = True

			if event.type == pygame.KEYDOWN:
				if event.key == pygame.K_LEFT:
					direction = "left"
					lead_x_change = -block_size
					lead_y_change = 0
				elif event.key == pygame.K_RIGHT:
					direction = "right"
					lead_x_change = block_size
					lead_y_change = 0
				elif event.key == pygame.K_UP:
					direction = "up"
					lead_y_change = -block_size
					lead_x_change = 0
				elif event.key == pygame.K_DOWN:
					direction = "down"
					lead_y_change = block_size
					lead_x_change = 0

			if lead_x<0 or lead_x>=display_width or lead_y<0 or lead_y>=display_height:
				gameOver = True

			# un-comment it to stop auto-pilot mode.
			# if event.type == pygame.KEYUP:
			# 	if event.key == pygame.K_LEFT or event.key == pygame.K_RIGHT:
			# 		lead_x_change = 0
			# 	elif event.key == pygame.K_UP or event.key == pygame.K_DOWN:
			# 		lead_y_change = 0
		
		lead_x +=lead_x_change
		lead_y +=lead_y_change

		gameDisplay.fill(white)

		AppleThickness = 30
		#so that the Apple stays within boundaries of frame.
		pygame.draw.rect(gameDisplay,red,[(randAppleX)%(display_width-AppleThickness),(randAppleY)%(display_height-AppleThickness),AppleThickness,AppleThickness])
		
		snakeHead = []
		snakeHead.append(lead_x)
		snakeHead.append(lead_y)
		snakeList.append(snakeHead)

		if len(snakeList)>snakeLength:
			del snakeList[0]

		for eachSegment in snakeList[:-1]:
			if eachSegment == snakeHead:
				gameOver = True

		snake(block_size,snakeList,direction)
		pygame.display.update()

		# if lead_x == randAppleX and lead_y == randAppleY:
		# 	snakeLength += 1
		# 	randAppleX = round(random.randrange(0,display_width-block_size)/10.0)*10
		# 	randAppleY = round(random.randrange(0,display_height-block_size)/10.0)*10
		# 	print "nom nom nom"

		# if lead_x <=randAppleX+AppleThickness and lead_x >= randAppleX:
		# 	if lead_y <=randAppleY+AppleThickness and lead_y >= randAppleY :
		# 		snakeLength += 1
		# 		randAppleX = round(random.randrange(0,display_width-block_size)/10.0)*10
		# 		randAppleY = round(random.randrange(0,display_height-block_size)/10.0)*10
		# 		print "nom nom nom"

		if lead_x>randAppleX and lead_x< randAppleX+AppleThickness or lead_x + block_size>randAppleX \
			and lead_x + block_size < randAppleX + AppleThickness:
			
			if lead_y>randAppleY and lead_y< randAppleY+AppleThickness:# or lead_y + block_size>randAppleX \
				snakeLength += 1
				randAppleX = round(random.randrange(0,display_width-block_size)/10.0)*10
				randAppleY = round(random.randrange(0,display_height-block_size)/10.0)*10

			elif lead_y + block_size > randAppleY and lead_y + block_size< randAppleY + AppleThickness:
				snakeLength += 1
				randAppleX = round(random.randrange(0,display_width-block_size)/10.0)*10
				randAppleY = round(random.randrange(0,display_height-block_size)/10.0)*10
		
		clock.tick(FPS)


	pygame.quit()
	quit() 
gameLoop()