crystal.Entity

Base class to inherit from to define entities.

In addition to the methods documented on this page, entities transparently expose all methods defined on their components. If multiple components share a method name, attempting to call it on the entity will emit an error detailing the ambiguity.

Methods

Name	Description
add_component	Instantiates and adds a new Component to this entity.
context	Retrieves a value added via ecs:add_context.
component	Returns a Component of a specific class or inheriting from it.
components	Returns all components of a specific class or inheriting fom it.
create_event	Instantiates and creates a new Event associated with this entity.
despawn	Unregisters this entity from the ECS.
ecs	Returns the ECS this entity belongs to.
is_valid	Returns whether this entity is still in play (ie. not despawned).
remove_component	Removes a component from this entity.

Examples

local Slime = Class("Slime", crystal.Entity);

Slime.init = function(self)
  self:add_component("OozeTrail");
end

local ecs = crystal.ECS:new();
ecs:spawn("Slime");

local Health = Class("Health", crystal.Component);
Health.init = function(self)
  self.amount = 100;
end

Health.take_damage(self, damage)
  self.amount = math.max(0, self.amount - damage);
end

local Slime = Class("Slime", crystal.Entity);

Slime.init = function(self)
  self:add_component("Health", 100);
end

local ecs = crystal.ECS:new();
local slime = ecs:spawn("Slime");
-- shorthand for slime:component("Health"):take_damage(10);
slime:take_damage(10);