Scene Game Tutorial. Episode 01

[stephen]

Files

Space Escape Episode 01

First step is to setup our Scene, View, and EventManager

Import:

ui Module is imported within scene Module and by importing scene using the * wildcard we can access ui through scene.
using * is the same as saying:

from scene import all

there is no Performance gain from this and if you import ui yourself it will use the same instance used within scene. only gain here is ww save a line of code.

Create a new script named main.py

from scene import *

---

Globals:

Avoid using Global Variables. Couple reasons for this is scene's EventLoop doesnt handle them properly and second there is no functionality to them. with a function you can apply Logic before returning the value and you return a new object each time so our Event loop does not need to maintain a reference to it.

A() => Action will be used for creating Animations In Later Episodes.

def A():
	return Action

---

EventManager

We will only have one EventManager each game session. Therefore we will not be using self to refer to an instance. Instead we will us cls to refer to the class object. Everything works just about the same only bug difference is we will be uing a Decorator for our methods called @classmethod this provides access to our class variables just like we would using self.

@classmethod stores a copy of the class dict inside cls

EventManager will be used to handle all the interactions between our game objects and Touch Events. We will Alo hanle and Timers we need to here.

• EventManager.main

• • reference to our Scene object

• EventManager.hud[^hud]

• • reference to our View object.

class EventManager(object):
    main=None
    hud=None

• EventManager.setup(*args)[^args]
• • Called before Scene.setup() inside our HUD.__init__()

    @classmethod
    def setup(cls, *args):
        cls.main=args[0]
        cls.hud=args[1]
        

• EventManager.update(dt)[^dt]
• • Called every frame from Scene.update and passed dt to be used with timers

    @classmethod
    def update(cls, dt):
        pass

• EventManager.touch_began(), EventManager.touch_moved(), EventManager.touch_ended()
• • Touch events send from Scene object

    @classmethod
    def touch_began(cls, touch):
        pass

    @classmethod
    def touch_moved(cls, touch):
        pass
    
    @classmethod
    def touch_ended(cls, touch):
        pass

---

Main:

Standard Scene setup providing all event calls to EventManager

class Main(Scene):
	def setup(self):
		pass
	
	def did_change_size(self):
		pass
	
	def update(self):
		EventManager.update(self.dt)
	
	def touch_began(self, touch):
		EventManager.touch_began(touch)
	
	def touch_moved(self, touch):
		EventManager.touch_moved(touch)
	
	def touch_ended(self, touch):
		EventManager.touch_ended(touch)

HUD:

main view container to hold all our ui elements. we are only setting our SceneView to display our Game's windown and calling EventManager.setup passing our HUD and Main refrences.

class HUD(ui.View):
	def __init__(self, *args, **kwargs):
		# Game Window
		self.main = SceneView(
			scene=Main(), frame=(5, 5, 600, 800),
			anti_alias=True,frame_interval=1,
			shows_fps=True, background_color='#2c00ff')
		self.add_subview(self.main)
		EventManager.setup(self.main.scene, self)

Finally if we are running this Script and not Importing it then present our game Windows!

if name=='main':
HUD().present('fullscreen', hide_title_bar=True)

---

In the next Episode we will start some Presetting And Setup Our Draft of the main menu

---

[^args]: args, kwargs, list arguments and dict keyword arguments
[^hud]: hud, Heads Up Diplay.
[^dt]: dt, DeltaTime, Time passed since last Frame. Set every Frame.

[mikael]

@stephen, just curious, what is the benefit or goal of using EventManager as ”class only”?

[stephen]

@mikael By using EventManager as a class and not creating an instance it insures i only have one EventManager at a time. since i handle the touch checks, timers, hit collision and other events in this class it should both keep fom using more memory from instances and should never be garbage collected since it maintains an update call from Scene.update .

[stephen]

@mikael lol well ive never checked the memory lol so in theory this is what i expect lol

[Swaffords]

This post is deleted!