Query:removed_components

Returns all components of a specific class (or inheriting from it) that stopped being part of a match for this query during the last call to ECS:update.

Components appear in this list when they meet 2 conditions:

1. Component is or was on an entity matched by this query
2. One of the following events happen:
   • Entity was despawned
   • Component was removed from its entity
   • Other components were removed from the entity so that it no longer matches the query

This method can return components on entities that were just despawned.

Usage

query:removed_components(class)

Arguments

Name	Type	Description
class	string or component class	Base class of the newly removed components that will be returned, as a string or as a reference.

Returns

Name	Type	Description
components	table	A table where every key is a removed Component. . Table values are the entities owning these components.

Examples

local Poison = Class("Poison", crystal.Component);
local PoisonSystem = Class("PoisonSystem", crystal.System);

PoisonSystem.init = function(self)
  self.query = self:add_query({ "Poison" });
end

PoisonSystem.frame = function(self)
  for poison in pairs(self.query:removed_components("Poison")) do
    print((tostring(poison:entity())) .. " is no longer poisoned");
  end
end