LÖVE

Posted: **Wed Mar 18, 2015 1:20 am**

In an effort to clean up some of the code I've been writing recently in Löve, I separated my game into a couple of files. Unfortunately, I'm finding that my enemies now have their sprite_index field come up as nil, even though they're being very explicitly set. My code looks like this:

Main.lua:

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require "math"
require "sprites"
require "player"
require "enemies"

math.randomseed(os.time())

function love.load()
  --images--
  love.graphics.setBackgroundColor(255,255,255)
  loadImages()
  --enemies--
  enemies = {}
  for i = 0,4 do
    table.insert(enemies,Enemy:new())
  end
end

Sprites.lua:

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function loadImages()
  spr_slice = love.graphics.newImage("slice.png")
  spr_agent = {}
  spr_agent[1] = love.graphics.newImage("agentf1.png")
  spr_agent[2] = love.graphics.newImage("agentf2.png")
  spr_player = {}
  spr_player[1] = love.graphics.newImage("playerf1.png")
  spr_player[2] = love.graphics.newImage("playerf2.png")
end

Enemies.lua:

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Enemy = {}
Enemy.sprite_index = spr_agent
Enemy.image_timer = 0
Enemy.image_index = 1
Enemy.image_speed = 3
Enemy.x = 0
Enemy.y = 0
Enemy.direction = math.random()*360
Enemy.speed = 2*60

Enemy.__index = Enemy

function Enemy:new(o)
  local o = o or {}
  setmetatable(o, Enemy)
  self.__index = self
  o.x = math.random()*love.graphics.getWidth()
  o.y = math.random()*love.graphics.getHeight()
  o.direction = math.random()*360
  return o
end

when I go to draw the enemies using the following code in main:

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for i,v in ipairs(enemies) do
    love.graphics.draw(v.sprite_index[v.image_index],math.floor(v.x),math.floor(v.y),0,sign(lengthdir_x(1,v.direction)),1,spr_agent[1]:getWidth()/2,spr_agent[1]:getHeight()/2)
  end

I'm told that sprite_index is a nil value. Can anybody identify a problem in my code that might be causing this? I'm still very new to Lua and Love, so please give as many details as you can.

Thanks in Advance,
Nicholas

Posted: **Wed Mar 18, 2015 1:42 am**

You set the variables in the wrong order.

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Enemy.sprite_index = spr_agent -- Here spr_agent is = nil
spr_agent = {} -- Now spr_agent becomes an table
               -- Enemy.sprite_index is still = nil

Be aware that the love.load() function is called after the variables outside functions is set.

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function love.load()
    a = 5
end
b = a -- This is calculated/run before the function love.load() is run.
      -- Which leads to b = nil

Posted: **Wed Mar 18, 2015 1:46 am**

Wow. I'm a little bit embarrassed that I missed that. Thanks very much for clearing up the confusion. It actually makes perfect sense, now.

LÖVE

separating files causes unexpected nil values

separating files causes unexpected nil values

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Re: separating files causes unexpected nil values