Game development with Pygame

Pygame Python

Welcome to the first tutorial of the series: Building games with Pygame. Games you create with Pygame can be run on any machine that supports Python, including Windows, Linux and Mac OS.

In this tutorial we will explain the fundamental of building a game with Pygame. We'll start of with the basics and will teach you how to create the basic framework. In the next tutorials you will learn how to make certain types of games.

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PyGame introduction You'll end up with a program similar to the one on the right:

A game always starts in an order similar to this (pseudo code):

initialize()
while running():
   game_logic() 
   get_input()
   update_screen()
deinitialize()

The game starts with initialization. All graphics are loaded, sounds are loaded, levels are loaded and any data that needs to be loaded. The game continues running until it receives a quit event. In this game loop we update the game, get input and update the screen. Depending on the game the implementation widely varies, but this fundamental structure is common in all games.

In Pygame we define this as:

import pygame
from pygame.locals import *
 
class App:
windowWidth = 640
    windowHeight = 480
    x = 10
    y = 10
def __init__(self):
        self._running = True
        self._display_surf = None
        self._image_surf = None
 
    def on_init(self):
        pygame.init()
        self._display_surf = pygame.display.set_mode((self.windowWidth,self.windowHeight), pygame.HWSURFACE)
        self._running = True
        self._image_surf = pygame.image.load("pygame.png").convert()
 
    def on_event(self, event):
        if event.type == QUIT:
            self._running = False
    
    def on_loop(self):
        pass
    
    def on_render(self):
        self._display_surf.blit(self._image_surf,(self.x,self.y))
        pygame.display.flip()
 
    def on_cleanup(self):
        pygame.quit()
 
    def on_execute(self):
        if self.on_init() == False:
            self._running = False
 
        while( self._running ):
            for event in pygame.event.get():
                self.on_event(event)
            self.on_loop()
            self.on_render()
        self.on_cleanup()
 
if __name__ == "__main__" :
    theApp = App()
    theApp.on_execute()

The Pygame program starts with the constructor __init__(). Once that is finished on_execute() is called. This method runs the game: it updates the events, updates the screen. Finally, the game is deinitialized using on_cleanup().

In the initialiasation phase we set the screen resolution and start the Pygame library:

def on_init(self):
        pygame.init()
        self._display_surf = pygame.display.set_mode((self.windowWidth,self.windowHeight), pygame.HWSURFACE)

We also load the image.

self._image_surf = pygame.image.load("pygame.png").convert()

This does not draw the image to the screen, that occurs in on_render().

def on_render(self):
        self._display_surf.blit(self._image_surf,(self.x,self.y))
        pygame.display.flip()

The blit method draws the image (image_surf) to the coordinate (x,y). In Pygame the coordinates start from (0,0) top left to (wind0wWidth, windowHeight). The method call pygame.display.flip() updates the screen.

Continue the next tutorial and learn how to add game logic and build games :-)

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