SNKRX/engine/game/state.lua

115 lines
2.9 KiB
Lua
Raw Normal View History

2021-02-18 05:11:25 +01:00
-- The base State class.
-- The general way of creating an object that implements these functions goes like this:
--[[
MyState = Object:extend()
MyState:implement(State)
function MyState:init(name)
self:init_state(name)
end
function MyState:on_enter(from)
end
function MyState:update(dt)
end
function MyState:draw()
end
]]--
-- This creates a new MyState class which you can then use to start writing your code.
-- Use the init function for things you need to do when the state object is created.
-- Use the on_enter function for things you need to do whenever the state gets activated.
-- By default, whenever a state gets deactivated it's not deleted from memory, so if you want to restart a level, for instance, whenever you switch states,
-- then you need to destroy everything that needs to be destroyed in an on_exit function and then recreate it again in the on_enter function.
--
-- You'd add a state to the game like this:
2021-02-18 19:28:40 +01:00
-- main:add(MyState'level_1')
2021-02-18 05:11:25 +01:00
-- You'd move to that state like so:
2021-02-18 19:28:40 +01:00
-- main:go_to'level_1'
-- main:go_to automatically calls on_exit for the currently active state and on_enter for the new one.
-- You can access the currently active state with main.current.
2021-02-18 05:11:25 +01:00
State = Object:extend()
function State:init_state(name)
self.name = name or random:uid()
self.active = false
end
2021-03-05 08:29:19 +01:00
function State:enter(from, ...)
2021-02-18 05:11:25 +01:00
self.active = true
2021-03-05 08:29:19 +01:00
if self.on_enter then self:on_enter(from, ...) end
2021-02-18 05:11:25 +01:00
end
2021-03-05 08:29:19 +01:00
function State:exit(to, ...)
2021-02-18 05:11:25 +01:00
self.active = false
2021-03-05 08:29:19 +01:00
if self.on_exit then self:on_exit(to, ...) end
2021-02-18 05:11:25 +01:00
end
-- The main state. This is a global state that is always active and contains all other states.
Main = Object:extend()
Main:implement(State)
function Main:init(name)
self:init_state(name)
self.states = {}
self.transitions = Group():no_camera()
end
function Main:update(dt)
for _, state in pairs(self.states) do
if state.active or state.persistent_update then
state:update(dt)
end
end
self.transitions:update(dt)
end
function Main:draw()
for _, state in pairs(self.states) do
if state.active or state.persistent_draw then
state:draw()
end
end
self.transitions:draw()
end
function Main:add(state)
self.states[state.name] = state
end
function Main:get(state_name)
return self.states[state_name]
end
-- Deactivates the current active state and activates the target one.
-- Calls on_exit for the deactivated state and on_enter for the activated one.
-- If on_exit returns true then the deactivated state will be removed from memory.
-- You must handle the destruction of it yourself in its on_exit function.
function Main:go_to(state, ...)
if type(state) == 'string' then state = self:get(state) end
if self.current then
if self.current.active then
if self.current:exit(state) then
self.states[state.name] = nil
end
end
end
local last_state = self.current
self.current = state
state:enter(last_state, ...)
end