Tags ​

Tags are special component types that store no value.

A tag can be created with:

local Tag = ecr.tag()

Tags types are used in the same way as any other component type. They are useful for marking entities in some state, and are more efficient than something like ecr.component() :: true.

Example usage:

local Selected = ecr.tag()

registry:add(id, Selected)
registry:has(id, Selected) -- true

registry:remove(id, Selected)
registry:has(id, Selected) -- false

local TargetPosition = ecr.component() :: Vector3

local function move_selected(position: Vector3)
    for id in world:view(Selected) do
        world:set(id, TargetPosition, position)
    end
end

To check if an entity has a tag, favor Registry:has() over Registry:get(), since tags have no value and will return nil.

You can check if a component type is a tag type or not with ecr.is_tag(ctype).