rose.md

Rose: A single-function ECS implementation.

To import it on your project:

• copy rose.lua into your project
• write local rose = require "rose"

Usage:

local rose = require "rose"
rose(entities, systems, process, etcetera)

How does ECS work?

Imagine you have a bunch of tables with all sorts of data, and you want all of them to act in a certain way depending on what data they contain, like the Entities of a game.

ECS works in a similar manner, a bunch of "systems" detect if said items fit a certain criteria, then do a set of operations on them if they do.

Those data items are named Entities by ECS.

Let's make a system

local system_screams = {
    filter = function(self, item)
        if item.has_mouth then
            return true
        end
    end,

    operate = function(self, item, what)
        print("I have a mouth and i must scream about " .. what .. "!")
    end
}

This system has a filter "method" which allows us to know if an item's has_mouth property is not nil.

If said check is true, the rest of the functions should run taking what as an argument.

Let's test it out with rose!

local systems = { system_screams }
local entities = {
    { has_mouth = true }
}

rose(entities, systems, "operate", "cheese")

In this example, rose will go through all the systems available and checks if the entities fit their descriptions through filter.

if filter returns non-nil and the function operate exists on the system, it will run over the entities.