How to make a function wait X amount time?

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Jeeper
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How to make a function wait X amount time?

Post by Jeeper » Tue Mar 19, 2013 1:40 am

I am very new to programming and coming from a "custom map" background in games like SC2. I am currently trying to make a platformer game in Love2d. But I wonder how I can make something wait X amount of seconds before doing the next thing.

Say I want to make the protagonist immortal for 5 seconds, how should that code look like ?
Immortal = true
????????????????
Immortal = false

As I have understood there is no built in wait in Lua nor Love2d.

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Qcode
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Re: How to make a function wait X amount time?

Post by Qcode » Tue Mar 19, 2013 1:52 am

Code: Select all

function love.load()
     immortal = true
     immortaltimer=0
end

function love.update(dt)
    immortaltimer = immortaltimer + dt
    if immortaltimer > 5 then
         immortal = false
    end
end
That should work. You'd adapt it to your own code, of course.

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miko
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Re: How to make a function wait X amount time?

Post by miko » Tue Mar 19, 2013 8:22 am

Jeeper wrote:I am very new to programming and coming from a "custom map" background in games like SC2. I am currently trying to make a platformer game in Love2d. But I wonder how I can make something wait X amount of seconds before doing the next thing.
Simple answer: you don't want to stop the lua code execution (so no real sleep()), because love loop has to run at 60 FPS or so, otherwise everything will be frozen and not responding.

If you really want your code to look like this:

Code: Select all

Immortal = true 
sleep(5)
Immortal = false
, you could use coroutines for that, like in this turtle example.
But if you are new to programming, the coroutine concept might be hard to you at start.
My lovely code lives at GitHub: http://github.com/miko/Love2d-samples

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adnzzzzZ
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Re: How to make a function wait X amount time?

Post by adnzzzzZ » Tue Mar 19, 2013 12:10 pm

I've created a library called chrono that can do just that!

To do what you asked with it:

Code: Select all

require 'chrono'

function love.load()
    ...
    immortal = false
    chrono = Chrono() -- create main chrono timer object
end

function love.update(dt)
    ...
    chrono:update(dt)
end

function love.keypressed(key)
    -- immortal for 5 seconds on p key press
    if key == 'p' then 
        chrono:after(0, function() immortal = true end):after(5, function() immortal = false end)
        -- same as this:
        -- immortal = true
        -- chrono:after(5, function() immortal = false end)
    end
end
Other libraries that provide similar functionality are kikito's cron and vrld's hump.timer.

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Jeeper
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Re: How to make a function wait X amount time?

Post by Jeeper » Tue Mar 19, 2013 2:56 pm

adnzzzzZ wrote:I've created a library called chrono that can do just that!

To do what you asked with it:

Code: Select all

require 'chrono'

function love.load()
    ...
    immortal = false
    chrono = Chrono() -- create main chrono timer object
end

function love.update(dt)
    ...
    chrono:update(dt)
end

function love.keypressed(key)
    -- immortal for 5 seconds on p key press
    if key == 'p' then 
        chrono:after(0, function() immortal = true end):after(5, function() immortal = false end)
        -- same as this:
        -- immortal = true
        -- chrono:after(5, function() immortal = false end)
    end
end
Other libraries that provide similar functionality are kikito's cron and vrld's hump.timer.
Wow, thanks a lot man! Your library is just what I was looking for. Really awesome :)

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Inny
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Re: How to make a function wait X amount time?

Post by Inny » Tue Mar 19, 2013 6:40 pm

As an alternative, coroutines can help.

Code: Select all

function love.load()
  run = coroutine.wrap(function()
    local clock = 5
    while clock > 0 do
      clock = clock - coroutine.yield(true)
    end
    -- waited 5 seconds, do your thing here.
  end)
end

function love.update(dt)
  run(dt)
end
More on coroutines in Programming In Lua, Chapter 9. http://www.lua.org/pil/9.html

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kikito
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Re: How to make a function wait X amount time?

Post by kikito » Tue Mar 19, 2013 9:30 pm

The idea is that you "remember" how much invincivility time the player has accumulated, until it's greater than the limit.

Code: Select all

local player = {isInvincible = false};

function startInvincibility()
  player.accumulatedInvincibilityTime = 0;
  player.isInvincible = true;
end

function updatePlayer(dt)
  if player.isInvincible then
    player.accumulatedInvincibilityTime = player.accumulatedInvincibilityTime + dt;
    if player.accumulatedInvincibilityTime > 5 then
      player.isInvincible = false
    end
  end
end

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

function love.draw()
  love.graphics.draw("Player invincible: " .. player.isInvincible);
end

function love.onkeypress()
  startInvincibility()
end
Notice that this code can be simplified quite a lot if you use a time management library. I have created one called cron.lua. The code above would become this:

Code: Select all

local cron = require 'cron'
local player = {isInvincible = false};

function startInvincibility()
  cron.cancel(player.timer);
  player.isInvincible = true;
  player.timer = cron.after(5, function() player.isInvincible = false end)
end

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

function love.draw()
  love.graphics.draw("Player invincible: " .. player.isInvincible);
end

function love.onkeypress()
  startInvincibility()
end
When I write def I mean function.

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arthurgps2
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Re: How to make a function wait X amount time?

Post by arthurgps2 » Tue Jan 31, 2017 9:46 pm

Well,i use [hump.timer] for it,there's a lot of ways to a function wait a x amount of time. I'm gonna show you two of them

First way
timer=require'hump.timer'

timer.after(x,function()
--Action
end)

Second way

timer=require'hump.timer'

timer.script(function(wait)
wait(x)
--Action
end)

So thats it,hope i helped ya ;D

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zorg
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Re: How to make a function wait X amount time?

Post by zorg » Wed Feb 01, 2017 4:50 am

arthurgps2 wrote:...
Congratulations for bumping a 4 year old thread with an unformatted whatever that was unneeded, this may be a record.
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.

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Positive07
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Re: How to make a function wait X amount time?

Post by Positive07 » Wed Feb 01, 2017 7:43 pm

Record indeed... We do need that no-necro feature!
for i, person in ipairs(everybody) do
[tab]if not person.obey then person:setObey(true) end
end
love.system.openURL(Github.com/Positive07)

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