Tag Archives: numpy

Creating a Snake Game using OpenCV-Python

Import Libraries

For this we only need four libraries

import numpy as np
import cv2
import random
import time

import numpy as np

import cv2

import random

import time

Displaying Game Objects

Game Window: Here, I have used a 500×500 image as my game window.

img = np.zeros((500,500,3),dtype='uint8')

1	img = np.zeros((500,500,3),dtype='uint8')

Snake and Apple: I have used green squares for displaying a snake and a red square for an apple. Each square has a size of 10 units.

# Displaying the snake (Green rectangles)
snake_position = [[250,250],[240,250],[230,250]]
for position in snake_position:
        cv2.rectangle(img,(position[0],position[1]),(position[0]+10,position[1]+10),(0,255,0),3)

# Displaying the snake (Green rectangles)

snake_position = [[250,250],[240,250],[230,250]]

for position in snake_position:

cv2.rectangle(img,(position[0],position[1]),(position[0]+10,position[1]+10),(0,255,0),3)

# Display apple (Red rectangles)
apple_position = [random.randrange(1,50)*10,random.randrange(1,50)*10]
cv2.rectangle(img,(apple_position[0],apple_position[1]),(apple_position[0]+10,apple_position[1]+10),(0,0,255),3)

# Display apple (Red rectangles)

apple_position = [random.randrange(1,50)*10,random.randrange(1,50)*10]

cv2.rectangle(img,(apple_position[0],apple_position[1]),(apple_position[0]+10,apple_position[1]+10),(0,0,255),3)

Game Rules

Now, let’s define some game rules

Collision with boundaries: If the snake collides with the boundaries, it dies.

def collision_with_boundaries(snake_head):
    if snake_head[0]>=500 or snake_head[0]<=0 or snake_head[1]>=500 or snake_head[1]<=0 :
        return 1
    else:
        return 0

def collision_with_boundaries(snake_head):

if snake_head[0]>=500 or snake_head[0]<=0 or snake_head[1]>=500 or snake_head[1]<=0 :

return 1

else:

return 0

Collision with self: If the snake collides with itself, it should die. For this, we only need to check whether the snake’s head is in snake body or not.

def collision_with_self(snake_position):
    snake_head = snake_position[0]
    if snake_head in snake_position[1:]:
        return 1
    else:
        return 0

def collision_with_self(snake_position):

snake_head = snake_position[0]

if snake_head in snake_position[1:]:

return 1

else:

return 0

Collision with apple: If the snake collides with the apple, the score is increased and the apple is moved to a new location.

def collision_with_apple(apple_position, score):
    apple_position = [random.randrange(1,50)*10,random.randrange(1,50)*10]
    score += 1
    return apple_position, score

def collision_with_apple(apple_position, score):

apple_position = [random.randrange(1,50)*10,random.randrange(1,50)*10]

score += 1

return apple_position, score

Also, on eating apple snake length should increase. Otherwise, snake moves as it is.

if snake_head == apple_position:
        apple_position, score = collision_with_apple(apple_position, score)
        snake_position.insert(0,list(snake_head))

    else:
        snake_position.insert(0,list(snake_head))
        snake_position.pop()

if snake_head == apple_position:

apple_position, score = collision_with_apple(apple_position, score)

snake_position.insert(0,list(snake_head))

else:

snake_position.insert(0,list(snake_head))

snake_position.pop()

Snake game has a fixed time for a keypress. If you press any button in that time, the snake should move in that direction otherwise continue moving in the previous direction. Sadly, with OpenCV cv2.waitKey() function, if you hold down the left direction button, the snake starts moving fast in that direction. So, to make the snake movement uniform, i did something like this.

    t_end = time.time() + 0.2
    k = -1
    while time.time() < t_end:
        if k == -1:
            k = cv2.waitKey(125)
        else:
            continue

t_end = time.time() + 0.2

k = -1

while time.time() < t_end:

if k == -1:

k = cv2.waitKey(125)

else:

continue

Because cv2.waitKey() returns -1 when no key is pressed, so this ‘k’ stores the first key pressed in that time. Because the while loop is for a fixed time, so it doesn’t matter how fast you pressed a key. It will always wait a fixed time.

Snake cannot move backward: Here, I have used the w, a, s, d controls for moving the snake. If the snake was moving right and we pressed the left button, it will continue moving right or in short snake cannot directly move backwards.

# 0-Left, 1-Right, 3-Up, 2-Down, q-Break
# a-Left, d-Right, w-Up, s-Down
if k == ord('a') and prev_button_direction != 1:
    button_direction = 0
elif k == ord('d') and prev_button_direction != 0:
    button_direction = 1
elif k == ord('w') and prev_button_direction != 2:
    button_direction = 3
elif k == ord('s') and prev_button_direction != 3:
    button_direction = 2
elif k == ord('q'):
    break
else:
    button_direction = button_direction

# 0-Left, 1-Right, 3-Up, 2-Down, q-Break

# a-Left, d-Right, w-Up, s-Down

if k == ord('a') and prev_button_direction != 1:

button_direction = 0

elif k == ord('d') and prev_button_direction != 0:

button_direction = 1

elif k == ord('w') and prev_button_direction != 2:

button_direction = 3

elif k == ord('s') and prev_button_direction != 3:

button_direction = 2

elif k == ord('q'):

break

else:

button_direction = button_direction

After seeing which direction button is pressed, we change our head position

if button_direction == 1:
    snake_head[0] += 10
elif button_direction == 0:
    snake_head[0] -= 10
elif button_direction == 2:
    snake_head[1] += 10
elif button_direction == 3:
    snake_head[1] -= 10

if button_direction == 1:

snake_head[0] += 10

elif button_direction == 0:

snake_head[0] -= 10

elif button_direction == 2:

snake_head[1] += 10

elif button_direction == 3:

snake_head[1] -= 10

Displaying the final Score

For displaying the final score, i have used cv2.putText() function.

if collision_with_boundaries(snake_head) == 1 or collision_with_self(snake_position) == 1:
    font = cv2.FONT_HERSHEY_SIMPLEX
    img = np.zeros((500,500,3),dtype='uint8')
    cv2.putText(img,'Your Score is {}'.format(score),(140,250), font, 1,(255,255,255),2,cv2.LINE_AA)
    cv2.imshow('a',img)
    cv2.waitKey(0)
    break

if collision_with_boundaries(snake_head) == 1 or collision_with_self(snake_position) == 1:

font = cv2.FONT_HERSHEY_SIMPLEX

img = np.zeros((500,500,3),dtype='uint8')

cv2.putText(img,'Your Score is {}'.format(score),(140,250), font, 1,(255,255,255),2,cv2.LINE_AA)

cv2.imshow('a',img)

cv2.waitKey(0)

break

Finally, our snake game is ready and looks like this

The full code can be found here.

Hope you enjoy reading.

If you have any doubt/suggestion please feel free to ask and I will do my best to help or improve myself. Good-bye until next time.

Greyscale and Color Image

Create own image using Numpy and OpenCV

Steps:

Create an array of any desired size using numpy. Always specify the ‘datatype’
Fill the values of the array using some logic
Show the image using cv2.imshow() or matplotlib.

Code:

import cv2
import numpy as np
import matplotlib.pyplot as plt

img = np.zeros((100,256),dtype=np.uint8)
for i in range(img.shape[1]):
    for j in range(img.shape[0]):
        img[j,i]=i

cv2.imshow('a',img)
cv2.waitKey(0)
cv2.destroyAllWindows()

#--------- using Matplotlib ------------
##plt.imshow(img, cmap = 'gray')
##plt.tick_params(axis='y',left = False,labelleft = False)
##plt.xticks([0,50,100,150,200,255])
##plt.show()

import cv2

import numpy as np

import matplotlib.pyplot as plt

img = np.zeros((100,256),dtype=np.uint8)

for i in range(img.shape[1]):

for j in range(img.shape[0]):

img[j,i]=i

cv2.imshow('a',img)

cv2.waitKey(0)

cv2.destroyAllWindows()

#--------- using Matplotlib ------------

##plt.imshow(img, cmap = 'gray')

##plt.tick_params(axis='y',left = False,labelleft = False)

##plt.xticks([0,50,100,150,200,255])

##plt.show()

The resulting image looks like this

To create a color image just specify the third dimension of the array (for example (100,256,3)) and rest is same.

Now, you are ready to create your own images. Hope you enjoy reading.

If you have any doubt/suggestion please feel free to ask and I will do my best to help or improve myself. Good-bye until next time.

Creating a Snake Game with pygame

7 Replies

In this tutorial, we will create a snake game with python and pygame. You can find full code here.

What is pygame?

It is a free and open source Python programming language library used for making a multimedia application like games. It is great for beginners as it’s simple and easy to use.

Installing pygame in Python:

There are two ways to do this.

You can directly use pip install pygame in the command window or
Download whl file from this link python extension packages according to your python version. Then use pip install whl_file_name.

Let’s create a snake game using pygame library. To Start with this, we first need to initialize pygame modules as shown below.

pygame.init()

1	pygame.init()

pygame.init() will attempt to initialize all the pygame modules for you. Not all pygame modules need to be initialized, but this will automatically initialize the ones that do.

Displaying Game Objects:

After initializing pygame modules, it’s time to display the game window. For that, we need to initialize its dimensions(width and height). Here I have used 500 x 500, but you can choose yours.

display_width = 500 
display_height = 500    
display = pygame.display.set_mode((display_width,display_height))
window_color= (200,200,200)
display.fill(window_color)
pygame.display.update()

display_width = 500

display_height = 500

display = pygame.display.set_mode((display_width,display_height))

window_color= (200,200,200)

display.fill(window_color)

pygame.display.update()

display.fill(window_color) will fill white color into game window and pygame.display.update() allows only a portion of the screen to be updated, instead of the entire area. If no argument is passed, it updates the entire Surface area.

This will create a game window as shown below.

Now it’s time to display snake and apple. Here I have used red color for snake and an image for apple. At the start of each game, we want snake’s starting position to be fixed while apple can take any random location. Starting length of the snake is 3 units where each unit is a 10×10 block.

red = (255,0,0)  
black = (0,0,0)
apple_image = pygame.image.load('apple.jpg') 
snake_head = [250,250] 
snake_position = [[250,250],[240,250],[230,250]] 
apple_position = [random.randrange(1,50)*10,random.randrange(1,50)*10]<strong>

def display_snake(snake_position):
    for position in snake_position:
        pygame.draw.rect(display,red,pygame.Rect(position[0],position[1],10,10))

def display_apple(display,apple_position, apple):
    display.blit(apple,(apple_position[0], apple_position[1]))
</strong>

red = (255,0,0)

black = (0,0,0)

apple_image = pygame.image.load('apple.jpg')

snake_head = [250,250]

snake_position = [[250,250],[240,250],[230,250]]

apple_position = [random.randrange(1,50)*10,random.randrange(1,50)*10]<strong>

def display_snake(snake_position):

for position in snake_position:

pygame.draw.rect(display,red,pygame.Rect(position[0],position[1],10,10))

def display_apple(display,apple_position, apple):

display.blit(apple,(apple_position[0], apple_position[1]))

</strong>

pygame.draw.rect() will draw a rectangle corresponding to given arguments which will represent our snake and display.blit() will show the image of an apple.

This will create a game window as shown below.

The next thing is to decide at what frame rate we want to play our game. This is done using pygame.time.Clock() that creates a “clock” object. Now whenever clock.tick() is called and passed with some number, then it will limit the run time speed of the game. As an example, if clock.tick(20) is called, then the program will never run at more than 20 frames per second.

clock = pygame.time.Clock()
clock.tick(20)

1 2	clock = pygame.time.Clock() clock.tick(20)

Game Logic:

Now it’s time to define game rules. As you know, there must be some rules which makes a game playable.

Rule 1: If the snake collapses with itself or with boundaries, game over.

def collision_with_boundaries(snake_head):
    if snake_head[0]>=500 or snake_head[0]<0 or snake_head[1]>=500 or snake_head[1]<0 :
        return 1
    else:
        return 0

def collision_with_self(snake_position):
    snake_head = snake_position[0]
    if snake_head in snake_position[1:]:
        return 1
    else:
        return 0

def collision_with_boundaries(snake_head):

if snake_head[0]>=500 or snake_head[0]<0 or snake_head[1]>=500 or snake_head[1]<0 :

return 1

else:

return 0

def collision_with_self(snake_position):

snake_head = snake_position[0]

if snake_head in snake_position[1:]:

return 1

else:

return 0

Rule 2: Moving the snake to a new position

In our game, the snake will continue to move in one direction until a button is pressed. To move the snake, we need to add one unit to the head and remove one unit from the tail.

 snake_position.insert(0,list(snake_head))
 snake_position.pop()

1 2	snake_position.insert(0,list(snake_head)) snake_position.pop()

Another case is when a button is pressed to move in a direction(left, right, up or down). Also, the Snake cannot move backward.

 if event.type == pygame.KEYDOWN:
    if event.key == pygame.K_LEFT and prev_button_direction != 1:
        button_direction = 0
    elif event.key == pygame.K_RIGHT and prev_button_direction != 0:
        button_direction = 1
    elif event.key == pygame.K_UP and prev_button_direction != 2:
        button_direction = 3
    elif event.key == pygame.K_DOWN and prev_button_direction != 3:
        button_direction = 2
    else:
        button_direction = button_direction

if event.type == pygame.KEYDOWN:

if event.key == pygame.K_LEFT and prev_button_direction != 1:

button_direction = 0

elif event.key == pygame.K_RIGHT and prev_button_direction != 0:

button_direction = 1

elif event.key == pygame.K_UP and prev_button_direction != 2:

button_direction = 3

elif event.key == pygame.K_DOWN and prev_button_direction != 3:

button_direction = 2

else:

button_direction = button_direction

After seeing which direction button is pressed, we need to change our snakes head position.

if button_direction == 1:
    snake_head[0] += 10
elif button_direction == 0:
    snake_head[0] -= 10
elif button_direction == 2:
    snake_head[1] += 10
elif button_direction == 3:
    snake_head[1] -= 10
else:
    pass

snake_position.insert(0,list(snake_head))
snake_position.pop()

if button_direction == 1:

snake_head[0] += 10

elif button_direction == 0:

snake_head[0] -= 10

elif button_direction == 2:

snake_head[1] += 10

elif button_direction == 3:

snake_head[1] -= 10

else:

pass

snake_position.insert(0,list(snake_head))

snake_position.pop()

Rule 3. If the snake eats an apple, the apple moves to a new position and snake length increases.

When the snake eats an apple, we increase our snake’s length and improve the score. To increase snake size, we add one unit at snake’s head. Also, we need to create another apple at random location to proceed the game.

def collision_with_apple(apple_position, score):
    apple_position = [random.randrange(1,50)*10,random.randrange(1,50)*10]
    score += 1
    return apple_position, score

if snake_head == apple_position:
    apple_position, score = collision_with_apple(apple_position, score)
    snake_position.insert(0,list(snake_head))

def collision_with_apple(apple_position, score):

apple_position = [random.randrange(1,50)*10,random.randrange(1,50)*10]

score += 1

return apple_position, score

if snake_head == apple_position:

apple_position, score = collision_with_apple(apple_position, score)

snake_position.insert(0,list(snake_head))

Displaying Final Score:

After the game is over, we want to display the final score. Here, I have defined a function ‘display_final_score’, which takes final score and text to be displayed as its arguments to display in the game window.

def display_final_score(display_text, final_score):
    largeText = pygame.font.Font('freesansbold.ttf',35)
    TextSurf = largeText.render(display_text, True, black)
    TextRect = TextSurf.get_rect()
    TextRect.center = ((display_width/2),(display_height/2))
    display.blit(TextSurf, TextRect)
    pygame.display.update()
    time.sleep(2)

def display_final_score(display_text, final_score):

largeText = pygame.font.Font('freesansbold.ttf',35)

TextSurf = largeText.render(display_text, True, black)

TextRect = TextSurf.get_rect()

TextRect.center = ((display_width/2),(display_height/2))

display.blit(TextSurf, TextRect)

pygame.display.update()

time.sleep(2)

This will display our final score as shown below.

Finally, our snake game is created, now it’s time to play it.

Now, you might have got some feeling about creating games using pygame. Hope you enjoy reading.

If you have any doubt/suggestion please feel free to ask and I will do my best to help or improve myself. Good-bye until next time.

Installing Python OpenCV and other libraries

1 Reply

Here, we will be installing the libraries that are required to perform image processing operations. We will be using the following Python libraries

OpenCV
Numpy
Matplotlib

Why we are using OpenCV, not Matlab or any other?

Because it is open source, fast(written in C/C++), memory efficient and easy to install (can run on any device that can run C).
if you really want to learn about how computer vision works from the initial steps to the last, I suggest you learn OpenCV first then use any deep learning library like Tensorflow, pytorch etc when you’re ready to train a deep learning algorithm for better performance/accuracy results.

Installing Numpy, OpenCV or any library (For WINDOWS)

There are two ways to install any library in Python IDLE,

using pip command: In the installed Python folder, go to Scripts folder and open command prompt(press and hold Shift + Right Click and select Open command window here). Then write pip install library name to get it installed. For example

Python

pip install numpy

1

pip install numpy
using .whl file: First download .whl file of any library (version corresponding to your Python) from here. Then open the command prompt where you have downloaded this file and write pip install filename.whl. For example

Python

pip install numpy‑1.14.2+mkl‑cp36‑cp36m‑win32.whl

1

pip install numpy‑1.14.2+mkl‑cp36‑cp36m‑win32.whl

Installing Numpy, OpenCV or any library (For UBUNTU)

First, install pip using apt-get, then you can install any library as shown below

sudo apt-get install python-pip  
sudo pip install numpy

1 2	sudo apt-get install python-pip sudo pip install numpy

Anaconda: open the Anaconda prompt and write pip install numpy or any other library name which you want to install.

Now, you might have got some feeling about how to install Python libraries. Hope you enjoy reading.

If you have any doubt/suggestion please feel free to ask and I will do my best to help or improve myself. Good-bye until next time.

TheAILearner

Mastering Artificial Intelligence

Tag Archives: numpy

Creating a Snake Game using OpenCV-Python

Import Libraries

Displaying Game Objects

Game Rules

Displaying the final Score

Greyscale and Color Image

Create own image using Numpy and OpenCV

Steps:

Code:

Creating a Snake Game with pygame

Installing Python OpenCV and other libraries