CODEWITHSUNDEEP
lualove2d
user3602465
user3602465

Reputation: 21

How to get delta time to work on love2d

Delta time wont work no matter what I try. I get this error

player.lua 39: attempt to perform arithmetic on global 'dt' (a nil value)

in function 'update'

in function 'player_move'

[C] in function: 'xpcall'

I did all the math right, it apparently thinks I'm talking about a non existent variable. Am I supposed to do dt = 1 ?

If I do that it still looks like it's moving at different paces occasionally, and no tutorial or documentation I've seen tells you to do that.

Upvotes: 2

Views: 3670

Answers (2)

pietroglyph
pietroglyph

Reputation: 41

You don't have to initialize the dt variable, it is already done for you. If you are trying to get the Delta Time in the love.update function you do have access to the dt variable out of the box and wont run into any trouble, but this variable is not global so if you are trying to access this in another place ( Say your love.draw function or player.lua ) you have three other options:

Use the Built in love.timer.getDelta function (Recommended)

This function is probably the best way to get the delta time. Here is an example usage:

whatever*love.timer.getDelta()

Pretty simple right!

Make a Global delta time variable

This isn't really the best way to do it, but it is an option. Here is a way to do it and some example usage:

In love.update:

function love.update(dt)
  DeltaTime = dt
end

Some Example Usage:

whatever = whatever*DeltaTime

Pass the Local dt variable to functions

This isn't a bad way to do it, the real problem with it is that it is that because you are calling your function from love.update so your function is getting called constantly ( and you might not want this. )

In love.update:

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

Some Example Usage:

function player_move(dt)
  whatever = whatever*dt
end

Upvotes: 2

Paul Kulchenko
Paul Kulchenko

Reputation: 26774

Make sure you define love.update function as love.update(dt) (see the example on love wiki); if you call your player_move function from love.update, then you'll need to add dt as a parameter to player_move and pass the value to it:

local function player_move(dt)
  -- do something with dt
end

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

Upvotes: 0

Related Questions