Can someone give me some straight up way to make simple game states?

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ThatChillHomie
Prole
Posts: 5
Joined: Sun Jun 10, 2018 1:52 am

Can someone give me some straight up way to make simple game states?

Post by ThatChillHomie »

I have been looking for ways to make game states in my game since I am new to programming but they all seem so ridiculous. Can one of you guys point me to the best simple way to do it? thanks
Titousensei
Prole
Posts: 13
Joined: Mon Aug 20, 2012 11:35 pm

Re: Can someone give me some straight up way to make simple game states?

Post by Titousensei »

Here's a technique I like to use. It's very simple, you just implement each state in its own .lua file as if it were main, and let main.lua dispatche the callbacks to the current state. (This example uses globals, but you can also do "local menu = {} ... return menu" if you prefer.)

main.lua

Code: Select all

require "menu"

local state = nil

function change_state(s)
  state = s
  state.load()
end

function love.load()
  print("Love version:", love._version, love._os)
  love.graphics.setBackgroundColor(0,0,0)
  -- Do more global inits here
  
  -- Then jump to the menu
  change_state(menu)
end

function love.draw()
  state.draw()
end

function love.update(dt)
  state.update(dt)
end

function love.mousepressed(x,y,b)
  if state.mousepressed then
    state.mousepressed(x,y,b)
  end
end

function love.mousereleased(x,y,b)
  if state.mousepressed then
    state.mousereleased(x,y,b)
  end
end

function love.keypressed(key)
  if key == "escape" then
    if state==menu then
      love.event.quit()
    else
      change_state(menu)
    end
  else
    state.keypressed(key)
  end
end
menu.lua

Code: Select all

-- loading the states I need here
require "game"
require "credits"

menu = {}

local selected = 1

function menu.draw()
  -- draw menu
  -- highlight selected
end

function menu.update(dt)
end

function menu.keypressed(key)
  -- handle menu controls
  if key == "return" or key == " " then
    if selected == 1 then
      change_state(game)
    elseif selected == 2 then
      change_state(credits)
    end
  elseif key == "up" then
    selected = 1
  elseif key == "down" then
    selected = 2
  end
end
credits.lua

Code: Select all

credits = {}

function credits.draw()
   -- draw menu
end

function credits.update(dt)
end

function credits.keypressed(key)
  -- any key goes back to menu
  change_state(menu)
end
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zorg
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Re: Can someone give me some straight up way to make simple game states?

Post by zorg »

Titousensei wrote: Sat Aug 04, 2018 6:53 pm Here's a technique I like to use. It's very simple, you just implement each state in its own .lua file as if it were main, and let main.lua dispatche the callbacks to the current state. (This example uses globals, but you can also do "local menu = {} ... return menu" if you prefer.)

(...)
That's cool and simple enough and all, but i think your solution that you've shown has at least one issue, at a glance:
- You're not guarding against the state functions not being defined; now you might say that it should be self-evident that update and draw must be, but you yourself call state.load in your change_state function, yet none of the states have a load function defined, which will error since you expect that to exist.
Me and my stuff :3True Neutral Aspirant. Why, yes, i do indeed enjoy sarcastically correcting others when they make the most blatant of spelling mistakes. No bullying or trolling the innocent tho.
Titousensei
Prole
Posts: 13
Joined: Mon Aug 20, 2012 11:35 pm

Re: Can someone give me some straight up way to make simple game states?

Post by Titousensei »

zorg wrote: Sun Aug 05, 2018 4:46 am That's cool and simple enough and all, but i think your solution that you've shown has at least one issue, at a glance:
- You're not guarding against the state functions not being defined; now you might say that it should be self-evident that update and draw must be, but you yourself call state.load in your change_state function, yet none of the states have a load function defined, which will error since you expect that to exist.
Ahah! True, this is not a complete solution, just an example of a method. I tried to show different options: mousepressed does guard against undefined, whereas draw and update do not. Some callbacks will be defined, some will not, depending on your project. It's simple enough to add the ifs when necessary.
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