bump.lua: 619: attempt to index field 'rects' (a nil value)

[wellslight]

As the title says, when I go to run this in LOVE 0.10.2 I get "bump.lua: 619: attempt to index field 'rects' (a nil value)." I have copied the function mentioned below. I am new to programming so I don't know how to fix this or work around it. Any help is appreciated!

function World:add(item, x,y,w,h)
local rect = self.rects[item] --this is line 619 and contains the "rects" referred to
if rect then
error('Item ' .. tostring(item) .. ' added to the world twice.')
end
assertIsRect(x,y,w,h)

self.rects[item] = {x=x,y=y,w=w,h=h}

local cl,ct,cw,ch = grid_toCellRect(self.cellSize, x,y,w,h)
for cy = ct, ct+ch-1 do
for cx = cl, cl+cw-1 do
addItemToCell(self, item, cx, cy)
end
end

return item
end

[DanielPower]

Can you post an example of your code which causes this error to occur?

[wellslight]

Thanks for the quick reply! Yeah, I'm just trying to make a simple tiled based top down game where I can walk the player around the screen. I want to have objects and buildings that the player won't walk through, but will bump into.
here's the gist of my code (it has a problem with the line just below "player.img" and just above "objects={}", where it calls for world.add(...)

`
local bump = require 'bump'

function love.load()
local world= bump.newWorld(32)
map = love.graphics.newImage("courtyard.png")
player = {}
player.speed = 120
player.x = 230
player.y = 580
player.w = 32
player.h = 32
player.dir = 0
player.move = true
player.img = love.graphics.newImage("char.png")
world.add(player, player.x, player.y, player.w, player.h)

objects= {}
objects.building = {}
objects.building.x = 416
objects.building.y = 256 - 32
objects.building.w = 96
objects.building.h = 128
objects.building.img = love.graphics.newImage("building.png")
world.add(objects.building, objects.building.x, objects.building.y, objects.building.w, objects.building.h)
end

function love.draw()
love.graphics.draw(map, 0,0)
--draw player
love.graphics.draw(player.img, up2, player.x, player.y)
end

function love.update(dt)
if player.x < 0 then player.x = 0 end
if player.y < 0 then player.y = 0 end
if player.x > 590 then player.x = 590 end
if player.y > 590 then player.y = 590 end

if player.move == true then
if love.keyboard.isDown("up") then player.y = player.y - player.speed * dt --and player.dir = 0
elseif love.keyboard.isDown("down") then player.y = player.y + player.speed * dt --and player.dir = 2
elseif love.keyboard.isDown("left") then player.x = player.x - player.speed * dt --and player.dir = 3
elseif love.keyboard.isDown("right") then player.x = player.x + player.speed * dt --and player.dir = 1
end

end
`

[kikito]

Hi there, the problem is that you wrote world.add(...). It should be world:add(...) (with : instead of .). In general, when you use bump, you should always write world:<method> and never world.<method>.

[wellslight]

Oh wow, such a simple fix. Thanks for catching that! I re-read that a thousand times and still didn't see the mistake.