separating files causes unexpected nil values

[LastNameGames]

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:

Code: Select all

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:

Code: Select all

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

[Evine]

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

[LastNameGames]

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.