Ejo

Yoruba Snake Game (June 2015)

This main purpose of this post is to describe how the game was built. Most of it is already covered in the video tutorial though. I just added all the Yoruba nonsense.

The game consists of:

Rules:

Setup

Pygame is a standard Python library for making games. It’s very popular and has great support. It’s the main module for the game. Pyganim is used here to add animations to the game.

In this phase we:

Animations

The way the animations work is mostly to create frames and go through them at pre-defined speeds. To make an infinite animation, you can create an infinite loop. For example:

game_overAnim = pyganim.PygAnimation([(images_path + 'game_over2.png', 150), (images_path + 'game_over3.png', 100)])
bonusAnim = pyganim.PygAnimation([(images_path+'bonus_text1.png', 150), (images_path+'bonus_text2.png', 100)])

while game_over is True:
		game_overAnim.play()

Screen Display

The pygame screen is a cartesian plane. What you have to do is write content to the screen at specified coordinates. After writing, you need to call pygame.display.update.

message_to_screen is a helper function used throughout the game to well, display a message to the screen. First, it gets the rendered font from calling text_objects and determines where the centre of the message should be.

def message_to_screen(msg, color, y_displace=0, x_displace=0, size="small", font=None, font_size=None):
    """
    :param msg:
    :param color:
    :param y_displace:
    :param x_displace:
    :param size:
    :param font:
    :param font_size:
    :return:
    """
    text_surf, text_rect = text_objects(msg, color, size, font, font_size)
    text_rect.center = (display_width/2) + x_displace, (display_height/2) + y_displace
    gameDisplay.blit(text_surf, text_rect)

def text_objects(text, color, size = None,  font = None, fontSize = None):
    """
    :param text:
    :param color:
    :param size:
    :param font:
    :param fontSize:
    :return:
    """
    text_surface = None

    if size == 'small':
        text_surface = small_font.render(text, True, color)
    elif size == 'medium':
        text_surface = med_fontButton.render(text, True, color)
    elif size == 'large':
        text_surface = large_font.render(text, True, color)
    elif font is not None:
        font = pygame.font.Font(r'C:\Users\Ope O\Downloads\Fonts' + '\\' + font , fontSize)
        text_surface = font.render(text, True, color)

    return text_surface, text_surface.get_rect()

gameDisplay.blit(image, x, y) is used to display images to the screen. You’d come across it often in the code.

Snake

The snake is a list, which is appended to increase the length etc. The main characteristics of the snake are:

  1. Length - As long as the items in the list, plus the length. Each item that’s not the head has a block size of 20.
  2. Health - Starts off at 90. Reduced by 30 if snake eats itself and totally if you enter the barrier.
  3. Skin - Each entry in the list (that is not the head) is displayed using an image loaded from source.
  4. Head - First list element. An image is used to depict this too.
  5. Direction - The snake moves in a direction by continuously adding to the coordinates in the main game loop. The default block size is 20.

     for event in pygame.event.get():
     		if event.type == pygame.QUIT:
     		    game_exit = 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
     		    elif event.key == pygame.K_p:
     		        pause()
        
     lead_x += lead_x_change
     lead_y += lead_y_change
        
     snake_head = list()
     snake_head.append(lead_x)
     snake_head.append(lead_y)
     snake_list.append(snake_head)
    

    When the direction is changed, the snake head needs to be rotated to face the direction it’s moving.

     def Snake(block_size, snake_list):
         """
         functionality for rotation
         :param block_size:
         :param snake_list:
         :return:
         """
        
         head = None
            
         if direction == 'right':
             head = pygame.transform.rotate(img, 270)
         if direction == 'left':
             head = pygame.transform.rotate(img, 90)
         if direction == 'up':
             head = img
         if direction == 'down':
             head = pygame.transform.rotate(img, 180)
        
         gameDisplay.blit(head, (snake_list[-1][0], snake_list[-1][1]))
        
         for XnY in snake_list[:-1]:
             gameDisplay.blit(skin,  (XnY[0], XnY[1]))
    
  6. Position - Each part of the snake’s body has it’s own (x & y) coordinates.

Game Loop

Most of the functionality of the game is implemented by running while loops, including what is called the main game loop. The loop is only exited on some user input e.g. exit.

Going back to calling pygame.display.update, the display needs to be updated after each iteration of the loop to ensure graphics are rendered properly.

In the while loops, various conditions are checked to determine if an action needs to be taken. Some examples of this are:

Eba

The eba is displayed using an image loaded from source. It’s main functionality is to be generated in pseudo-random positions for the user to chase, and re-generate when it’s ‘eaten’.

The apple thickness is a global variable set by default to 30.

def randAppleGen():
    """
    :return:
    """
    rand_apple_x = round(random.randrange(40, display_width - AppleThickness - 40))
    rand_apple_y = round(random.randrange(30, display_height - AppleThickness - 30))

    return rand_apple_x, rand_apple_y

Score

The score is text displayed at the upper right corner.

def score_update(score):
    """
    :param score:
    :return:
    """
    text = small_font.render('Score: ' + str(score), True, white)
    gameDisplay.blit(text, [display_width - 765,20])

Health Bar

def health_bars(snake_health):
    """
    :param snake_health:
    :return:
    """
    if snake_health > 75:
        snake_health_color = green
    elif snake_health > 50:
        snake_health_color = yellow
    else:
        snake_health_color = red
    health_text = small_font.render('Health: ', True, white)
    gameDisplay.blit(health_text,[display_width-210, 20])
    pygame.draw.rect(gameDisplay, black , (display_width-131, 25, 92, 22))
    pygame.draw.rect(gameDisplay, white , (display_width-130, 26, 90, 20))
    pygame.draw.rect(gameDisplay, snake_health_color , (display_width-130, 26, snake_health, 20))

Screenshots

Running in Docker

I tried to put the app in a container for the purpose of this post, but couldn’t. I’ll publish another post soon about that whole process and why it might not be a dead-end.

Tbh though, all you really need is to have Python on your machine and probably ability to create a virtualenv.

Ideas/Improvements

  1. Soundtrack.
  2. Storyline.
  3. Different levels e.g. random obstacles get introduced at higher levels.
  4. High Score.

If you want to see the entire picture, the repo is open-source here. Feel free to clone and contribute.

Hi! My name is Opeyemi. I like distributed systems, NodeJS, Golang and Puff Puff. You can learn more about me or message me on Twitter.

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