Appkit: /unit_link.lua — code sample

Code

--[[

A component to control linking (attaching) one unit to another. This is a very
thin wrapper around World.link_unit and World.unlink_unit.

]]--

require 'core/appkit/lua/class'
require 'core/appkit/lua/component_manager'

Appkit.UnitLink = Appkit.class(Appkit.UnitLink)
local UnitLink = Appkit.UnitLink

local World = stingray.World

Appkit.ComponentManager.give_manager(UnitLink)

-- If is_linked is not supplied then will link by default.
function UnitLink:init(entity, level, child_unit, child_node_index, parent_unit, parent_node_index, is_linked)
    local world = stingray.Level.world(level)

    self.world = world
    self.entity = entity
    self.child_unit = child_unit
    self.child_index = child_node_index
    self.parent_unit = parent_unit
    self.parent_index = parent_node_index

    if is_linked == nil or is_linked == true then
        World.link_unit(world, child_unit, child_node_index, parent_unit, parent_node_index)
    end

    self.is_linked = is_linked

    UnitLink.manager:add_component(entity, self, level) -- pass level to register for on_level_shutdown
end

function UnitLink:set_parent(parent_unit, parent_node_index)
    self.parent_unit = parent_unit
    self.parent_index = parent_node_index
end

function UnitLink:set_child(child_unit, child_node_index)
    self.child_unit = child_unit
    self.child_index = child_node_index
end

function UnitLink:link()
    if self.is_linked == true then
        print "UnitLink:link: Cannot link, already linked to a unit!"
        return
    end

    if self.child_unit and self.child_index and self.parent_unit and self.parent_index then
        World.link_unit(self.world, self.child_unit, self.child_index, self.parent_unit, self.parent_index)
        self.is_linked = true
    end
end

function UnitLink:unlink()
    if self.is_linked == false then
        print "UnitLink:unlink: Not linked to a unit!"
        return
    end

    World.unlink_unit(self.world, self.child_unit)
    self.is_linked = false
end

function UnitLink:update(dt)
end

function UnitLink:on_level_shutdown()
    self:unlink()
end

function UnitLink:shutdown()
    self:unlink()
end

return UnitLink