[SOLVED] ubuntu pygame window not showing up in snake

Issue

So, I was watching a video from youtube on making the game Snake on Python with the pygame module.. and it was quite confusing.. and now I'm having an issue.. The pygame window opened and closed suddenly and there was no errors in the output.

I ran this pile of code :

import os
os.environ['DISPLAY'] = ': 0.0' 
import pygame
pygame.init()
import random
from enum import Enum
from collections import namedtuple

font = pygame.font.Font('PermanentMarker-Regular.ttf', 25)
#font = pygame.font.SysFont('arial', 25)

class Direction(Enum):
    RIGHT = 1
    LEFT = 2
    UP = 3
    DOWN = 4


Point = namedtuple('Point', ('x','y'))

WHITE = (255, 255, 255)
RED = (247,33,25)
BLUE = (0,0,255)
CYAN = (255, 255, 1)
BLACK = [0,0,0]


BLOCK_SIZE = 20
SPEED = 40
class SnakeGame:
    def __init__(self, w=640, h=480):
        self.w = w
        self.h = h
        # init display
        self.display = pygame.display.set_mode((self.w, self.h))
        pygame.display.set_caption("Snake")
        self.clock = pygame.time.Clock()


        # init game state 
        self.direction = Direction.RIGHT

        self.head = Point(self.w/2, self.h/2)
        self.snake = [self.head, Point(self.head.x-BLOCK_SIZE, self.head.y), Point(self.head.x-(2*BLOCK_SIZE), self.head.y)]

        self.score = 0
        self.food = None
        self._place_food()

    def _place_food(self):
        x = random.randint(0, (self.w-BLOCK_SIZE)//BLOCK_SIZE) * BLOCK_SIZE
        y = random.randint(0, (self.h-BLOCK_SIZE)//BLOCK_SIZE) * BLOCK_SIZE
        self.food = Point(x, y)
        if self.food in self.snake:
            self._place_food()
            self.head = Point(x,y)        

    def _move(self, direction):
        x = self.head.x
        y = self.head.y
        if direction == Direction.RIGHT:
            x += BLOCK_SIZE
        elif direction == Direction.LEFT:
            x -= BLOCK_SIZE
        elif direction == Direction.UP:
            y -= BLOCK_SIZE
        elif direction == Direction.DOWN:
            y += BLOCK_SIZE

    def _is_collision(self):
        # hits boundary
        if self.head.x > self.w - BLOCK_SIZE or self.head.x < 0 or self.head.y > self.h - BLOCK_SIZE or self.head.y < 0:
            return True
        # hits itself
        if self.head in self.snake[1:]:
            return True
        return False

        pygame.display.flip()



    def play_step(self):
        # collect user input
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                pygame.quit()
                quit()
            if event.type == pygame.KEYDOWN:
                if event.key == pygame.K_LEFT:
                    self.direction = Direction.LEFT
                elif event.key == pygame.K_RIGHT:
                    self.direction = Direction.RIGHT
                elif event.key == pygame.K_UP:
                    self.direction = Direction.UP
                elif event.key == pygame.K_DOWN:
                    self.direction = Direction.DOWN
        #2. move
        self._move(self.direction)
        self.snake.insert(0, self.head)

        #3. check if game over
        game_over = False
        if self._is_collision():
            game_over = True
        #4. place new food or move snake
        if self.head == self.food:
            self.score += 1
            self._place_food()
        else:
            self.snake.pop()

        #5. update ui and clock
        self._update_ui()
        self.clock.tick(SPEED)
        #6. return game over and score
        return game_over, self.score

    def _update_ui(self):
        self.display.fill(BLACK)
    
        for pt in self.snake:
            pygame.draw.rect(self.display, CYAN, pygame.Rect(pt.x, pt.y, BLOCK_SIZE, BLOCK_SIZE))
            pygame.draw.rect(self.display, BLUE, pygame.Rect(pt.x+4, pt.y+4, 12, 12))
        
        pygame.draw.rect(self.display, RED, pygame.Rect(self.food.x, self.food.y, BLOCK_SIZE, BLOCK_SIZE))

        text = font.render("Score:", str(self.score), True, WHITE)
        self.display.blit(text, [0,0])

if __name__ == '__main__':
    game = SnakeGame()

    # game loop
    while True:
        game_over, score = game.play_step()

        if game_over == True:
            break
    print("Final score {}".format(score))
        # break if game over


    pygame.quit()

The issue is probably because I misplaced a method or did something in the script..

Solution

There are 4 issues:

1. Update the head attribute after in the move() method:

class SnakeGame:
    # [...]

    def _move(self, direction):
        x = self.head.x
        y = self.head.y
        if direction == Direction.RIGHT:
            x += BLOCK_SIZE
        elif direction == Direction.LEFT:
            x -= BLOCK_SIZE
        elif direction == Direction.UP:
            y -= BLOCK_SIZE
        elif direction == Direction.DOWN:
            y += BLOCK_SIZE

        self.head = Point(x, y)        # <--- this is missing

2. You have to concatenate the strings for the score text (see TypeError: Invalid foreground RGBA argument):

text = font.render("Score:", str(self.score), True, WHITE)

text = font.render("Score:" + str(self.score), True, WHITE)

3. Update the display after drawing the scene:

def _update_ui(self):
        self.display.fill(BLACK)
    
        for pt in self.snake:
            pygame.draw.rect(self.display, CYAN, pygame.Rect(pt.x, pt.y, BLOCK_SIZE, BLOCK_SIZE))
            pygame.draw.rect(self.display, BLUE, pygame.Rect(pt.x+4, pt.y+4, 12, 12))
        
        pygame.draw.rect(self.display, RED, pygame.Rect(self.food.x, self.food.y, BLOCK_SIZE, BLOCK_SIZE))

        text = font.render("Score:" + str(self.score), True, WHITE)
        self.display.blit(text, [0,0])
        
        pygame.display.flip()          # <--- this is missing

4. Use pygame.time.Clock to control the frames per second and thus the game speed.

The method tick() of a pygame.time.Clock object, delays the game in that way, that every iteration of the loop consumes the same period of time. See pygame.time.Clock.tick():

This method should be called once per frame.

if __name__ == '__main__':
    game = SnakeGame()

    # game loop
    clock = pygame.time.Clock()
    while True:
        clock.tick(10)

        game_over, score = game.play_step()

        if game_over == True:
            break
    print("Final score {}".format(score))

---

Answered By - Rabbid76