wecs 0.2.1a0

An ECS (entity component system)

What is WECS?

WECS stands for World, Entities, Components, Systems. It implements the architecture pattern known as [ECS, EC, Component system (and probably by several other names as well)] (https://en.wikipedia.org/wiki/Entity_component_system), which is popular in game development.

WECS aims at putting usability first, and to not let performance optimizations compromise it.

Beyond the core which implements the ECS, the goal of WECS is to accumulate enough game mechanics and boilerplate code so that the time between imagining a game and getting to the point where you actually work on your specific game mechanics is down to a few minutes.

In particular, systems and components to work with the Panda3D engine are provided.

Installation, etc.

• Installation: pip install wecs
• Documentation: readthedocs.io
• Source code: GitHub repository
• Chat: Panda3D Offtopic Discord server, channel #wecs

Hello World

from wecs.core import *

world = World()

A world contains Entities; Also Systems, more about those later.

entity = world.create_entity()

Entities themselves contain Components; They are also nothing more than a container for components. They are a general form of "game object", and can be turned into more specific objects by adding Components to them.

Components are data structures with no inherent functionality (i.e. they have no functions). Their presence on an entity describes the state of an aspect of that entity. For example, a certain game object could be the player's car, having a Geometry component with its graphical model, a Car component describing things like motor power and fuel in the tank, a PhysicsBody keeping track of the car's representation in the physics simulation, and many more. Or it could be something as simple as "An entity with this component can count", or "It can print its count (if it has one)":

@Component()
class Counter:
    count: int = 0

@Component()
class Printer:
    name: str = "Bob"

entity.add_component(Counter())
entity.add_component(Printer())

During each world.update(), the World will go through its list of Systems, and run each in turn. Each System has a list of Filters which test whether System should process an entity, and in what kind of role.

class CountAndPrint(System):
    entity_filters = {
        'count': Counter,
        'print': and_filter(Counter, Printer),
    }

    def update(self, entities_by_filter):
    for entity in entities_by_filter['count']:
        entity[Counter].count += 1
    for entity in entities_by_filter['print']:
        msg = "{} has counted to {}.".format(
	    entity[Printer].name,
	    entity[Counter].count,
	)
	print(msg)

world.add_system(CountAndPrint(), 0)

The 0 in world.add_system(CountAndPrint(), 0) is the sort of the system. Systems are run in ascending order of sort. As an aside, it'd be a good idea to break this into two systems; Who knows what else other people want to happen between counting and printing?

Now we can step time forward in this little universe:

world.update()
Bob has counted to 1.

This concludes the Hello World example.