pygame code organization

Question

I've started to learn making games with python/pygame and as though it is easy to make a working game quickly in pygame, there's no real tutorial on how to organize the code in a sensible way.

On the pygame tutorials page, I've found 3 ways to do it.

1- No use of classes, for small projects

2- MVC ruby-on-rails kind of structure but without the rails framework which results in something overly complicated and obscure (even with OO programming and rails knowledge)

3- C++-like structure as follows: (clean and intuitive but maybe not very much python-like?)

import pygame
from pygame.locals import *

class MyGame:
    def __init__(self):
        self._running = True
        self._surf_display = None
        self.size = self.width, self.height = 150, 150
    def on_init(self):
        pygame.init()
        self._display_surf = pygame.display.set_mode(self.size)
        pygame.display.set_caption('MyGame')
        #some more actions
        pygame.display.flip()
        self._running = True
    def on_event(self, event):
        if event.type == pygame.QUIT:
            self._running = False
        elif event.type == KEYDOWN:
            if event.key == K_ESCAPE:
                self._running = False
        elif event.type == MOUSEBUTTONDOWN:
            if event.button == 1:
                print event.pos
    def on_loop(self):
        pass
    def on_render(self):
        pass
    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__" :
    mygame = MyGame()
    mygame.on_execute()

I'm used to make SDL games in C++ and I use this exact structure but I'm wondering if it's usable for both small and large projects or if there's a cleaner way in pygame.

For example I found a game organized like this:

imports

def functionx
def functiony

class MyGameObject:
class AnotherObject:
class Game: #pygame init, event handler, win, lose...etc
while True: #event loop
display update

It also looks very well organized and easy to follow.

Which structure should I use consistently in all my projects so as to have a clean code usable in small and large games?

MVC has been around in some form as long as there have been GUI's. Your 'C++ structure' are really the controller part of MVC. Anytime your wating for an event with an on_foo method your probably using some form of MVC. martinfowler.com/eaaDev/uiArchs.html — nate c
I'm trying to write a simple game using pygame and I find your approach very interesting, but could you explain what do we need to do in on_loop() and on_render() methods? As I understand it in on_render we make some drawings, right? And in on_loop() we perform some logic. Is it correct? — DaZzz

nchpmn nchpmn · Accepted Answer · 2011-01-06T09:25:36

I'd also suggest maybe using comments (as dreary as it seems as first) for dividing your work. As an example:

import pygame, random, math

## CLASSES ----------------------------------------------

class Ball():
    def __init__(self, (x,y), size):
        """Setting up the new instance"""
        self.x = x
        self.y = y
        self.size = size

## FUNCTIONS --------------------------------------------
def addVectors((angle1, length1), (angle2, length2)):
    """Take two vectors and find the resultant"""
    x = math.sin(angle1) * length1 + math.sin(angle2) * length2
    y = math.cos(angle1) * length1 + math.cos(angle2) * length2

## INIT -------------------------------------------------

width = 600
height = 400
screen = pygame.display.set_mode((width, height))
pygame.display.set_caption("S-kuru")

And so on.

As another option to consider, have you thought about using sub-modules? They're just other Python files (.py) where you place commonly-used functions.

def showText(passedVariable):
    print passedVariable
    return

This new file is the imported, just as math or random would be and the function used as such:

import mySubModule

mySubModule.showText("Hello!")

But that's just how I work. Absolutely follow what you can understand, not just now but next week or year also.

pygame code organization

2 Answers