A scene and event manager for python arcade
Arcade-curtains is a basic scene and event manager for Arcade. The main goal is to provide a way to write event driven games instead of plastering your code with ifs and elses. This is achieved by writing handlers for events.
There are two types of events.
Sprite mouse events:
You can attach your event handlers on a per sprite basis. Meaning each sprite/event combination could have a unique handler.
Scenes are a way to pipe events to a certain context. You can define sprites and events in one scene, and they will become inactive when you enter another scene, for which you can define a whole new set of sprites and events. It also allows you to write some setup or teardown code when entering or leaving scenes.
When switching from one scene to another, the context and state of the previous scene is still retained. Meaning you can easily switch between scenes and continue where you previously had left off. A quick example would be accessing a menu or inventory in the middle of a level.
Eventhough this way of writing games allows for a more modular approach, ultimately leading to more readable code, it's easy to lose track of execution flow when debugging. Therefore it is advised to write your handlers to directly handle what you want to achieve instead of diverging into a number of different code paths based on the state of the game.
In addition to this, the library has not yet been benchmarked and so it's not known at what point the event handler gets saturated.
Binding Curtains to Arcade
As the library itself is pretty basic, getting started is fairly easy. The first thing you have to do is create an instance of the Curtains class, and bind it to your Arcade window.
import arcade from arcade_curtains import Curtains class Window(arcade.Window): def __init__(self): super().__init__(SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_TITLE) self.curtains = Curtains(self)
import arcade from arcade_curtains import Curtains class Window(arcade.Window): def __init__(self): super().__init__(SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_TITLE) curtains = Curtains() window = Window() curtains.bind(window)
When you bind the Curtains instance to an Arcade window, it will immediately bind itself to the window event methods (e.g.
on_mouse_motion). From then on, it will pipe the events to the event manager of the currently selected scene.
You are still able to overload these Arcade window methods as normal, but it is not advised to do so. If you do, know that the code written in these functions will be executed first, and Curtains handlers after.
Creating a Scene
Scenes are the basis of this library, and when using curtains, every game needs at least one.
Once you've defined your Curtains instance, you can add a scene to it. But to be able to do this, you will have to subclass the
BaseScene class provided by
arcade-curtains and overload the setup method.
In the setup method you can run all code that is making sprites, spritelists and linking your handlers.
BaseScene will auto detect
SpriteList instances and auto draw on each frame.
import arcade from arcade_curtains import Curtains, BaseScene class MyOpeningScene(BaseScene): def setup(self): # Actors will automatically be picked up and drawn on each frame self.actors = arcade.SpriteList() self.actor = arcade.Sprite() class Window(arcade.Window): def __init__(self): super().__init__(SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_TITLE) self.curtains = Curtains(self) self.curtains.add_scene('opening_scene', MyOpeningScene()) self.curtains.set_scene('opening_scene')
Now that we've initialized curtains to have a scene, we can start adding events.
As explained above, there are two types of events. Unfortunately, these types are still a bit obfuscated at this point and are treated the same way, from a code point of view. The only difference is that for the sprite events, you need to give the sprite to the manager when registering a handler.
Sprite events usually occur when an interraction is being done with a specific sprite.
Let's create a scene with one actor and add a
import arcade from arcade_curtains import BaseScene from .my_custom_sprites import CustomSprite def paint_border(sprite, x, y): sprite.set_border_texture() def unpain_border(sprite, x, y): sprite.unset_border_texture() def kill_actor(sprite, x, y): sprite.play_death_animation(callback=sprite.kill) class MyOpeningScene(BaseScene): def setup(self): self.actors = arcade.SpriteList() self.actor = CustomSprite() # add a hover event to this scene that paints a border whenever the mouse hovers over the sprite self.events.hover(self.actor, paint_border) # add an out event that reverts back to the original texture self.events.out(self.actor, unpain_border) # and one that kills the actor when clicked self.events.click(self.actor, kill_actor)
Some events are not linkable to a sprite, but you would still like to define some handlers to it. For instance the
frame event, which is triggered at every frame. You could treat it as a sprite event, but it wouldn't make sense as it doesn't get triggered due to sprite interaction. Instead, you can just attach a handler function, that interracts with the desired sprite, to the
import arcade from arcade_curtains import BaseScene class CustomSprite(arcade.Sprite): def spin(self, delta_time): self.angle += delta_time self.angle %= 360 class MyOpeningScene(BaseScene): def setup(self): self.actors = arcade.SpriteList() self.actor = CustomSprite() self.events.frame(sprite.spin)
Alternatively you can add a handler that doesn't interract with a sprite in any way.
import random import arcade from arcade_curtains import BaseScene COLORS = [getattr(arcade.color, color) for color in dir(arcade.color)] def trip_balls(delta): arcade.set_background_color(random.choice(COLORS)) class MyOpeningScene(BaseScene): def setup(self): self.events.frame(trip_balls)
Adding keyboard events is equally easy, and uses the arcade keymap to define handlers
import sys import arcade from arcade_curtains import BaseScene def exit(key): sys.exit(0) class MyOpeningScene(BaseScene): def setup(self): self.events.key(arcade.key.ESCAPE, exit)
A planned addition to this library is an animation manager that is able to animate until a condition is met. (An example of how that would work can be found in
The current Arcade animations are a bit black and white, meaning you have to manually turn it on or off. The animation manager would be a "fire and forget" principle. You could tell the sprite to move to a given location, or grow to a given scale, at a given speed, and you can trust the manager to take care of everything and cleaning up after the animation is done.
Download the file for your platform. If you're not sure which to choose, learn more about installing packages.
|Filename, size||File type||Python version||Upload date||Hashes|
|Filename, size arcade_curtains-0.0.1-py2.py3-none-any.whl (8.3 kB)||File type Wheel||Python version py2.py3||Upload date||Hashes View hashes|
|Filename, size arcade-curtains-0.0.1.tar.gz (13.3 kB)||File type Source||Python version None||Upload date||Hashes View hashes|
Hashes for arcade_curtains-0.0.1-py2.py3-none-any.whl