Nata

Nata is a library for LÖVE that creates entity pools. It can be used in either a traditional OOP style or a simple ECS style.

See the demos folder for some examples - the shooter example uses OOP, while the platformer example uses ECS.

Installation

To use Nata, place nata.lua in your project, and then add this code to your main.lua:

nata = require 'nata' -- if your nata.lua is in the root directory
nata = require 'path.to.nata' -- if it's in subfolders

Usage - OOP style

Creating an entity pool

pool = nata.new()

Adding an entity to the pool

entity = pool:add(entity)

Adds an entity to the pool and returns the entity.

Calling an event for all entities

pool:call(event, ...)

For each entity, this will run entity:[event](...) if the entity has a function called event. Any additional arguments passed to pool.call will be passed to each entity's function.

Calling an event for a single entity

pool:callOn(entity, event, ...)

Getting entities

entities = pool:get(f)

Returns a table containing all the entities for which f(entity) returns true. For example, this code will return a table with all the entities that are marked as "solid":

solidEntities = pool:get(function(entity)
  return entity.solid
end)

If no function is provided, pool:get() will return every entity.

Sorting entities

pool:sort(f)

Sorts the entities according to the function f. This works just like table.sort.

Removing entities

pool:remove(f)

Removes all the entities for which f(entity) returns true and calls the "remove" event on each entity that is removed.

Usage - ECS style

ECS style is almost exactly the same as OOP style, except you pass a list of systems to nata.

pool = nata.new(systems)

Each system is a table with an optional filter function and a function for each event it should respond to. Each event function will receive an entity first, followed by any additional arguments passed to pool.call, pool.callOn, pool.add, or pool.remove. For example, a gravity system might look like this:

GravitySystem = {
  filter = function(entity)
    return entity.vy and entity.gravity
  end,
  update = function(entity, dt)
    entity.vy = entity.vy + entity.gravity * dt
  end,
}

Nata's OOP functionality is implemented as a single system that passes every event (except for "filter" and "add") to the entity. If you want to use this system in combination with other systems, add nata.oop to the systems table.

Contributing

This library is in very early development. Feel free to make suggestions about the design. Issues and pull requests are always welcome.

License

MIT License

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

pablomayobre/nata