Window and Game loop - Madour/pyNasNas GitHub Wiki

Window parameters

ns.App.__init__ takes a bunch of arguments :

• title (str) : title of your window
• w_width (int) : window width
• w_height (int) : window height
• v_width (int) : game camera width
• v_height (int) : game camera height
• fps (int) : desired fps (you'll never obtain exactly this value)

Let's go back to game.py, and add some parameters to the window :

# src/game.py
import NasNas as ns

class Game(ns.App):
    def __init__(self):
        super().__init__(title="My SFML Project", w_width=1200, w_height=675, fps=100)
        # you can change sfml RenderWindow properties (see SFML documentation)
        # by accessing self.window 
        self.window.key_repeat_enabled = False
        self.window.vertical_synchronization = True

The Game Loop

The game loop is started when you call the run() method. What it does :

while window.is_open : 
    for event in window.events :
          self.event_handler(event)
    self.update()
    self.render()

All of this is done under the hood, and you don't have to write it. You only have to write your own event_handler() and update() methods

Event handler

The event handler lets you interact with any window, keyboard, mouse or joystick event.

In your project's game.py, let's add this method:

# src/game.py
import NasNas as ns
from sfml import sf

class Game(ns.App):
    def __init__(self):
        super().__init__(title="My SFML Project", w_width=1200, w_height=675, fps=100)
        # you can change sfml RenderWindow properties (see SFML documentation)
        # by accessing self.window 
        self.window.key_repeat_enabled = False
        self.window.vertical_synchronization = True

    def event_handler(self, event):
        if event == sf.Event.KEY_PRESSED:
            if event['code'] == ns.Keyboard.ESCAPE:
                self.window.close()
            elif event['code'] == ns.Keyboard.Q:
                print('Q key pressed')

You can run main.py and press Q , the message will be printed. Press Escape to close the window. You can find a full list of events in SFML documentation.

Update

The update() method is called every frame. In this method, you write most of your game logic (moving sprites, playing a sound, doing a transformation ...).

For now, we don't have any sprites, but we can still use it, add the following code to your Game class :

    def update(self):
        # this will be printed every frame
        print("Updating game !")

Render

The render() method is called every frame, immediately after update(). It automatically draws your game scenes on the window.

You are not supposed to override or call it !

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