In this tutorial we will learn how to create a snake game using python and curses.
What is Curses?
The curses is a library that can be used to create text user interface application. It is terminal controlled library i.e. the code written using curses can only be run through terminal.
Import Libraries
To start with creating a snake game using curses, we first need to import the following libraries:
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import random import curses import time |
The above import will work fine for Linux based systems, to make it compatible for windows you need to install curses. To do this you need to download curses for windows according to your python version from python extension packages and then run the following command:
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pip install curses‑2.2‑cp36‑cp36m‑win_amd64.whl |
Initializing Game Screen
After importing required libraries, first we need to initialize game screen and get the maximum height and width of the opened terminal screen. Using these height and width we will create a window for the game.
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sc = curses.initscr() h, w = sc.getmaxyx() win = curses.newwin(h, w, 0, 0) win.keypad(1) curses.curs_set(0) |
In the above code win.keypad(1) will initiate the keyboard to take the user’s input for the game. Also curses.curs_set(0) will set the cursor mode to be invisible in the screen.
Initialize snake and apple initial positions
Next, we will initialize the snake and apple(food) starting positions in the game screen. Also, we will initialize our game score to be zero.
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snake_head = [10,15] snake_position = [[15,10],[14,10],[13,10]] apple_position = [20,20] score = 0 win.addch(apple_position[0], apple_position[1], curses.ACS_DIAMOND) key = curses.KEY_RIGHT |
In the above code win.addch() will add a diamond like symbol in the game screen according to specified apple position.
Specifying Game Over Conditions
For the snake game there are basically two conditions which defines how game will end. First if snake collide with one of the game window boundaries and second if snake collides with itself.
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def collision_with_boundaries(snake_head): if snake_head[0]>=h-1 or snake_head[0]<=0 or snake_head[1]>=w-1 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 |
Playing the Game
In this game we will use four keyboard buttons, ‘up’, ‘down’, ‘left’ and ‘right’. To get a user input from keyboard we need to use win.getch() function.
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win.border(0) win.timeout(100) next_key = win.getch() if next_key == -1: key = key else: key = next_key |
In the above code win.border(0) will create a border around our game screen.
Now we will see the logic to move snake and eat apple. According to the game rules, snake will continue to move in the same direction if user do not press any button. Also snake can not move backward. In case user press any button, we need to update snake head’s position. Let’s see code:
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if key == curses.KEY_LEFT and prev_button_direction != 1: button_direction = 0 elif key == curses.KEY_RIGHT and prev_button_direction != 0: button_direction = 1 elif key == curses.KEY_UP and prev_button_direction != 2: button_direction = 3 elif key == curses.KEY_DOWN and prev_button_direction != 3: button_direction = 2 else: pass prev_button_direction = button_direction if button_direction == 1: snake_head[1] += 1 elif button_direction == 0: snake_head[1] -= 1 elif button_direction == 2: snake_head[0] += 1 elif button_direction == 3: snake_head[0] -= 1 |
Next there are two situations. One, in next step snake will move to a new position and second, in next step snake will eat apple. In case snake only moves to a new position, we will add one unit at it’s head and remove one unit from its tail according to the pressed direction. Another situation, if snake eats apple then we will add one unit at snake’s head and do not remove from it’s tail. We will also display a new apple at different location. Let’s see the code:
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def collision_with_apple(score): apple_position = [random.randint(1,h-2),random.randint(1,w-2)] score += 1 return apple_position, score if snake_head == apple_position: apple_position, score = collision_with_apple(score) snake_position.insert(0, list(snake_head)) win.addch(apple_position[0], apple_position[1], curses.ACS_DIAMOND) else: snake_position.insert(0, list(snake_head)) last = snake_position.pop() win.addch(last[0], last[1], ' ') |
Then finally we will display the score in the screen and quit the game window.
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sc.addstr(10, 30, 'Your Score is: '+str(score)) sc.refresh() time.sleep(2) curses.endwin() |
Here are some images of the game that we have just created.
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.